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The transferability of diatoms to clothing and the methods appropriate for their collection and analysis in forensic geoscience
Abstract
Forensic geoscience is concerned with the analysis of geological materials in order to compare and exclude environmental samples from a common source, or to identify an unknown provenance in a criminal investigation. Diatom analysis is currently an underused technique within the forensic geoscience approach, which has the potential to provide an independent ecological assessment of trace evidence. This study presents empirical data to provide a preliminary evidence base in order to be able to understand the nature of diatom transfers to items of clothing, and the collection of transferred diatom trace evidence from a range of environments under experimental conditions. Three diatom extraction methods were tested on clothing that had been in contact with soil and water sites: rinsing in water (RW), rinsing in ethanol (RE), and submersion in H 2 O 2 solution (H). Scanning electron microscopy (S.E.M.) analysis was undertaken in order to examine the degree of diatom retention on treated clothing samples. The total diatom yield and species richness data was recorded from each experimental sample in order to compare the efficacy of each method in collecting a representative sample for analysis. Similarity was explored using correspondence analysis. The results highlight the efficiency of H 2 O 2 submersion in consistently extracting high diatom counts with representative species from clothing exposed to both aquatic and terrestrial sites. This is corroborated by S.E.M. analysis. This paper provides an important empirical evidence base for both establishing that diatoms do indeed transfer to clothing under forensic conditions in a range of environments, and in identifying that H 2 O 2 extraction is the most efficient technique for the optimal collection of comparative samples. There is therefore potentially great value in collecting and analysing diatom components of geoforensic samples in order to aid in forensic investigation.
... However, it remains unclear whether a particular aquatic environment can be identified based on the analysis of diatoms isolated from clothing or footwear. So far, studies have been carried out on the transfer and persistence of diatoms on various footwear materials (37), as well as their transfer to clothing, such as cotton shirts (38,39); in addition, various methods of extracting diatoms from different types of places and materials have also been analyzed (40,41). All these studies confirmed the presence, transferability, and preservation of diatom material on various types of substrates. ...
... Most of the information published so far on the possibility of using diatoms to identify a crime scene based on obtained environmental traces from elements of clothing and footwear have been obtained from studies carried out in laboratory conditions (37,38,48). ...
... All studies carried out so far in terms of diatom transfer and their persistence on selected footwear and clothing materials have been conducted in laboratory conditions (37,38,48) and in the Investigators can use that evidence at any stage of the forensic investigation process. ...
Environmental analysis of soil, water, and plants plays a key role in the criminal investigation process, as it not only provides information about the course of the crime, but it can also elucidate the connection between the offender, the victim, and the environment. One particularly useful way of linking the victim and offender to a specific environment is by analyzing their clothing for the presence of diatoms. The present research was conducted upon field experiments. Firstly, it examines the variability of diatom and the quantitative analysis of diatom communities in designated places, each at an increasing distance from the aquatic ecosystem. Secondly, it analyses the differentiation of the structure of diatom communities in designated environments located close to each other. Thirdly, it examines the diatom colonization of selected substrates: cotton, chamois leather, and sponge. Finally, it confirms whether the diatoms which transfer to socks after contact with the selected environment reflect the structure of the diatom communities in that environment, even after the socks had been washed. Our findings indicate that diatom communities vary considerably, even between environments separated by short distances, and that objects placed in a particular environment are colonized by diatoms that reflect the environmental samples, irrespective of the substrate. In addition, after contact with a specific aquatic ecosystem, sock material retained diatom collections that reflected the environment samples, even though the time of exposure was very short and after the socks had been washed. This provides valuable information that can be used as forensic evidence.
... Structured studies pertaining to evidence transfer, persistence, and preservation allow inferences made in forensic casework to be evidence-based and the significance of any findings transparently established [3]. This paper contributes to the growing research literature within forensic diatom analysis [4][5][6], through assessment of the persistence dynamics of diatoms as circumstantial trace indicators hours, days, and weeks post-initial transfer. ...
... Although diatom trace evidence analysis is documented in casework [19][20][21], the corresponding research base is relatively recent in its development. Previous studies have tested different techniques for diatom recovery from clothing and footwear, with a H 2 O 2 extraction protocol shown to generate an abundant and species-rich forensic sample [4]. Diatoms are transferred to clothing and footwear following brief periods of immersion [4,5] although the extent of this transfer is significantly affected by environmental variability, recipient surface characteristics, and diatom morphology [6,22]. ...
... Previous studies have tested different techniques for diatom recovery from clothing and footwear, with a H 2 O 2 extraction protocol shown to generate an abundant and species-rich forensic sample [4]. Diatoms are transferred to clothing and footwear following brief periods of immersion [4,5] although the extent of this transfer is significantly affected by environmental variability, recipient surface characteristics, and diatom morphology [6,22]. Persistence has briefly been tested on footwear, with diatoms retrievable after one week of continued wear [5]. ...
Freshwater diatoms offer valuable circumstantial forensic indicators, with a growing empirical research base aiming to identify and understand some of the spatial and temporal factors affecting their validity as trace evidence. Previous studies demonstrated that recipient surface characteristics, environmental variability, and individual species traits influence the initial transfer of freshwater diatoms to clothing. However, no previous research has sought to consider the impact of these and other variables on the persistence of transferred diatoms over investigative timescales. Therefore, this study aimed to identify and explore diatom retention dynamics on clothing following wear over time (hours to weeks). A series of experiments were designed to examine the impact of clothing material, seasonality, and time since wear (persistence interval) on the total number and species-richness of diatoms recovered and their relative retention (%) over time. Nine clothing swatches were immersed in a freshwater environment and then worn for one month in the spring. Subsamples were retrieved at regular intervals (e.g. 30 mins, 1 h, 8 h, 24 h) up to one month, diatoms were extracted using a H2O2 method, and examined microscopically. Three clothing materials were subject to the same experiment in the winter to generate a seasonal comparison. The results broadly identified three stages of diatom persistence on clothing – rapid initial loss, variable intermediate decay, and sustained long-term presence. Clothing material significantly impacted the number of diatoms recovered and retention dynamics over time, with complex interactions identified with seasonality. Although fewer diatoms were recovered in the winter, overall retention trends were consistent at the different times of year. The findings demonstrate that diatoms can be recovered from clothing, even weeks or months after an initial transfer, yielding a useful environmental trace indicator for forensic reconstructions over investigative timescales. The impact of clothing material and seasonality on persistence identified cotton, acrylic, and viscose clothing as the most reliable temporal repository of diatom trace evidence, with a more abundant forensic assemblage available for forensic comparisons in the spring.
... Diatoms are a species-rich group of unicellular algae (Bacillariophyceae), frequently used as indicators of drowning in forensic pathology [12], and as a form of environmental trace evidence [13]. There are over 12,000 known species, all characterised by a resistant silica cell wall and species-specific valve features and ornamentation [14]. ...
... Previous forensic studies have demonstrated that diatom transfer is affected by immersion time, clothing substrate, seasonality, and valve/species characteristics (e.g. shape) [13,15]. Additional persistence research indicates diatom retention on footwear [16] and clothing [7] following weeks of wear, although the species dynamics of a persistent assemblage have not yet been explored. ...
... Swatches of each clothing material were removed from the whole garment, attached to a pair of waterproof trousers, immersed, and walked through a 5 m transect of the River Beane (Hertfordshire, UK) (National Grid Ref: TL313148). Diatom transfer was initiated for 3 min [13]. To provide a reference of the diatom species present at the scene, a 500 ml sample of water and any suspended material was collected from the same transect. ...
Diatoms are a useful form of environmental trace evidence, yielding a circumstantial link between persons and scenes of forensic interest. A developing empirical research base has sought to understand those factors affecting the transfer and persistence of freshwater diatoms on clothing and footwear surfaces. Although an initial study has demonstrated that diatoms can persist on clothing following weeks of wear, no previous research has explored the temporal dynamics of a persistent species assemblage over timescales pertinent to forensic investigations. This study therefore aimed to determine if: (1) valve morphology (size and shape) influences diatom persistence, (2) the relative abundance of taxa within an assemblage affects retention, and (3) a persistent diatom assemblage retrieved from clothing after one month can reliably be compared to the site of initial transfer. To build on previous research findings which highlighted the impact of substrate and environmental seasonality on diatom transfer and persistence, here, nine clothing materials were tested in spring before a seasonal comparison in the winter. Fabric swatches were immersed in a freshwater river, worn attached to clothing, and subsamples retrieved at regular intervals (hours, days, weeks) up to one month post-immersion. Diatoms were extracted using a H2O2 technique and analysed via microscopy. The results indicated that smaller diatoms (<10μm) are retained in significantly greater abundance, with no statistically significant difference between centric and pennate diatom loss over time. Although a persistent species assemblage was relatively stable over the one month of wear, significant differences were identified between clothing substrate in the spring and between the seasonal samples. The most abundant environmental taxa were consistently identified in the forensic samples, with greater variability attributed to the retention of relatively less common species. The findings suggest that, despite a loss in the abundance and species-richness of diatoms retrieved from clothing over time, a persistent assemblage may provide a useful circumstantial link to the site of initial transfer. The complex relationships between clothing type, environmental seasonality, and time since wear on retention, emphasise the need for diatom trace evidence to be carefully interpreted within an exclusionary framework, and the significance of any casework findings to be determined with reference to empirical evidence bases.
... In order to overcome these investigative limitations, in the last few years scientists have investigated the possibility of using trace evidence related to the aquatic environment, for crime scene reconstruction [7][8][9][10]. This idea stems from the forensic dogma "every contact leaves a trace" -known as Locard's exchange principle [11] and in the field of forensic geoscience [12]. ...
... This idea stems from the forensic dogma "every contact leaves a trace" -known as Locard's exchange principle [11] and in the field of forensic geoscience [12]. In this context, forensic geoscience refers to the possibility of using trace evidence such as soil, sediment and microscopic algae (diatoms especially), to support the diagnosis of death by drowning [13,14] and to verify that contact occurred between a suspect and a specific water body [8,15]. ...
... Diatomite can be used to produce water filters, insecticides, dermatological and nutritional products [20]. These unique characteristics, the ease of transfer from environment to victims/suspects, coupled with the fact that diatoms are almost unknown to perpetrators, make them of great forensic value [8,21]. ...
Crime scene investigation protocols and procedures are well established when concerning terrestrial environments, but are limited when associated with aquatic environments.
In aquatic contexts, the soil, sediments and microscopic algae (e.g. diatoms) may all be used as sources of trace evidence for criminal investigations. Diatoms are one such source that can be used to support the diagnosis of death by drowning and can be used to verify contact between a suspect and a specific water body. For the latter, diatoms can be collected from clothing and shoes for forensic comparisons. Over the years, there have been several methods proposed for the extraction of diatoms from clothing however, a best practice method is yet to be established and is still open to debate.
The present research represents the first investigation that evaluates four different methods for the extraction of native and common Australian diatom species from four different types of fabrics. Diatoms of two different species and shape (pennate and centric) were cultivated in stimulated experimental waters – prepared using either monocultures or mixed cultures of the selected diatoms. Diatom concentrations were set to mimic the natural population (low to bloom events) as commonly found in the Swan River Estuary of Western Australia. Cotton, denim, blend, and acrylic fabric types were placed in experimental waters. Diatom extraction was attempted using methods already proposed in the literature, these include: rinsing with ethanol (RE); rinsing with ethanol together with the application of centrifugal force (RECF); digestion with hydrogen peroxide (H); and a new method of ashing that has never tested before (dry ash, DA).
Results of this research showed that a) the type and the concentration of the mono and mix diatom mixtures significantly affects the transfer and extraction from different types of fabric; b) a noticeable extraction difference is observed between the fabrics, establishing denim, acrylic and blend fabrics as possessing the better extraction rates; c) H treatment had the highest extraction rate of diatoms; d) the application of centrifugal force on the RE method significantly improved the extraction of diatoms; e) DA is a potential method for the extraction of pennate-shaped diatoms from all of the tested fabrics, however does have a tendency to induce modifications of the morphological structure of the diatoms. Overall, the application of different extraction methods is suggested to maximize the extraction of diatoms that would closely reflect the natural assemblage in the water body under investigation.
... Several case examples within the literature consider the successful application of freshwater algae as trace evidence in various investigative scenarios (Siver et al. 1994;Cameron 2004), however empirical research studies generating additional intelligence within the field are relatively recent (Scott et al. 2014). Growing calls within the forensic science community, from both academics and policy makers, increasingly identify the need for research to establish empirical evidence bases for forensic application (Mnookin et al. 2011; Annual Report of the Government Chief Scientific Adviser 2015). ...
... The individual properties of a soil sample have traditionally been observed using light and electron microscopy methods (Dawson and Hillier 2010). Optical analyses allow for the examination and identification of individual particulates such as quartz grain surface textures , pollen grains (Wiltshire 2015), and diatom valves (Scott et al. 2014). A growing area of research is directed towards improving the range and efficiency of those techniques available for the analysis of geoforensic evidence types. ...
... • the wide distribution and natural abundance of organisms in a range of environments; • the diverse nature of individual taxa and the overall species composition at a site in line discrete ecological conditions; • and the microscopic size of individual organisms-enhancing the potential for transfer and limiting the possible removal of evidence (Scott et al. 2014). ...
Environmental trace evidence is often encountered during a forensic investigation and is acknowledged to have the potential to contribute valuable circumstantial information pertaining to the context of an individual criminal event. Although traditional study has focused upon the analysis of terrestrial soil and sediment traces, there is growing potential for the forensic assessment of aquatic crime scenes, particularly those within freshwater environments. This paper outlines the current applications of limnology, particularly algae and diatom analysis, within forensic science and introduces new and ongoing research within the field. Two empirical studies are presented which highlight the importance of developing evidence bases within freshwater trace evidence analysis. These studies demonstrate the analytical capability of the Scanning Electron Microscope (SEM) at various stages of an investigation: in the initial screening and collection of an evidential sample from clothing (1); and in the analysis of preserved diatoms following various levels of their exposure to fire damage (2). The results highlight that the SEM provides a valuable tool during the initial stages of an investigation, determining the presence and abundance of a range of environmental indicators and directing further strategy for the more in-depth collection and analysis of a forensic sample. Furthermore, the preservation of diatoms adhering to clothing following prolonged exposure to fire, indicates that efforts to collect any destroyed evidence are worthwhile given the potential to recover freshwater traces over extended time scales. Finally, the value of adopting an empirical approach for the development of a forensically relevant evidence base within forensic limnology, and the importance of having an appreciation of the legal implications for the interpretation and admissibility of freshwater evidence is presented.
... Rudolf von Hösslin, an Austrian scientist, was the first to propose the application of diatoms in forensics in 1913. Throughout the mid-twentieth century, forensic diatomology made significant advancements in terms of methodology and techniques (Uitdehaag et al. 2010;Scott et al. 2014). To extract and analyze the diatoms from different types of biological samples, such as lung tissues (Horton 2007), bone marrow (Lunetta 2016;Levkov et al. 2017a), and from clothing (Zhou et al. 2020), scientists developed a variety of extraction and analysis techniques, which included techniques like chemical digestion, filtration, and microscopic examination. ...
... Samples could be contaminated via multiple sources, like sample collection site itself, laboratory contamination, cross-sample contamination, airborne contamination, sample storage unit contamination, and reagent contamination. False positives are generally a result of contamination, but cross-reactivity (between multiple diatom samples) and human errors (methodological or interpretation errors) can also lead to inaccurate results (Horton 2007;Verma 2013;Scott et al. 2014). ...
Background
Forensic diatomology is a rapidly progressing domain that involves the examination of microscopic algae known as diatoms for forensic purposes. Diatoms are microscopic, single-celled, eukaryotic algae that exist in diverse aquatic environments such as rivers, lakes, ponds, and oceans. They are characterized by their rigid cell wall made up of silica, which is a unique morphological character, making them useful for forensic investigations.
Main body
Diatoms are a type of unicellular microscopic algae that belong to the class Bacillariophyta . They are one of the most common phytoplankton found in all aquatic environments, including marine and freshwater habitats. Diatoms have proven to be valuable evidence in various forensic investigations, particularly in cases involving drowning or bodies recovered from aquatic environments.
Conclusion
This comprehensive review provides an in-depth analysis of the principles, methodologies, applications, and challenges associated with the field of forensic diatomology. It emphasizes the importance of diatoms as trace evidence and discusses their potential to establish critical associations between the victim and the surroundings. This review also explores some recent advancements in diatom analysis techniques, including molecular approaches and automated identification methods. Finally, the paper outlines future directions for research and underlines the necessity for standardized protocols and interdisciplinary collaborations to enhance the reliability and validity of forensic diatomology.
... Ekologi forensik terdiri atas entomologi forensik (Alexa et al., 2022;Greenberg, 1991;Tomberlin et al., 2011), ekologi tanah forensik dan mikroba forensik (Demanèche et al., 2017;Finley et al., 2015), botani (palinologi) forensik (Bock, 2013;Nguyen & Weber, 2015;Schield et al., 2016;Wiltshire, 2009), fenologi (Bock & Norris, 2016a, 2016b, limnologi forensik (Kakizaki et al., 2019;Levin et al., 2017;Liu et al., 2020;Marezza et al., 2021;Scott et al., 2014Scott et al., , 2017Scott et al., , 2019Thakar & Singh, 2010;Zhao et al., 2016;Zimmerman & Wallace, 2008), geoforensik (Ruffell & McKinley, 2005;Scott et al., 2014). Dalam prakteknya di lapangan atau tempat kejadian perkara, peran ekologi forensik sering dihubungkan dengan kondisi lingkungan dan fenologi suatu jasad hayati yang terlibat atau berada dalam tubuh korban (Wiltshire, 2019). ...
... Ekologi forensik terdiri atas entomologi forensik (Alexa et al., 2022;Greenberg, 1991;Tomberlin et al., 2011), ekologi tanah forensik dan mikroba forensik (Demanèche et al., 2017;Finley et al., 2015), botani (palinologi) forensik (Bock, 2013;Nguyen & Weber, 2015;Schield et al., 2016;Wiltshire, 2009), fenologi (Bock & Norris, 2016a, 2016b, limnologi forensik (Kakizaki et al., 2019;Levin et al., 2017;Liu et al., 2020;Marezza et al., 2021;Scott et al., 2014Scott et al., , 2017Scott et al., , 2019Thakar & Singh, 2010;Zhao et al., 2016;Zimmerman & Wallace, 2008), geoforensik (Ruffell & McKinley, 2005;Scott et al., 2014). Dalam prakteknya di lapangan atau tempat kejadian perkara, peran ekologi forensik sering dihubungkan dengan kondisi lingkungan dan fenologi suatu jasad hayati yang terlibat atau berada dalam tubuh korban (Wiltshire, 2019). ...
Biologi forensik merupakan cabang ilmu forensik yang menggunakan pendekatan biologis dari skala jasad hingga molekuler dalam mengungkap suatu kebenaran bukti hayati. Dalam penerapannya, biologi forensik melibatkan banyak bidang ilmu lain untuk memaksimalkan pengungkapan bukti kebenaran. Biologi forensik dewasa ini telah berkembang menjadi bagian penting dalam ilmu forensik dan kriminologi untuk mengungkap kasus kejahatan kriminal. Studi ini memberikan penjabaran bagaimana ilmu biologi dapat berkontribusi dalam ilmu forensik, dari segi pandangan, fundamental ilmu forensik hayati, dan peran biologi dalam mengungkap kebenaran.
... Introduction: Diatoms are unicellular microalgae ubiquitous in lotic or lentic aquatic ecosystems, though they can also be found on humid land surfaces, even if less frequently [1,2]. Individual species and communities are diverse and environmentally specific due to their sensitivity to pH, temperature, and type of aquatic ecosystem [3,4]. ...
... Diatoms have been of great importance in forensic investigation providing a useful tool for the diagnosis of drowning. In fact, objects of a crime or persons linked to an accident or crime scene that takes place in water will have algae in or on them [1,2,3]. Objectives: This work focuses on the significance of diatoms in the diagnosis of drowning death cases. ...
... Such variation depends upon the method's accuracy or systematic error (determined by the specificity (true negative rate) and sensitivity (true positive rate), together with a threshold above which the method can be called 'reliable' [11]), as well as on information on its precision or random error (their repeatability and reproducibility) [3,12]. In addition, factors may influence parameter values post-event, such as environmental conditions and collection strategies [13,14]. 'Unreliable expert evidence' then relates to the extent to which the meaning of the uncertainty caused by such factors are and can be considered in the interpretation and presentation stages of the forensic science process. ...
... More generally, the time between the rulings does not always correspond with the time spent incarcerated, as, for example, the suspect may have been incarcerated before the trial date or have already completed their sentence before the appeal. The cases involved significant crimes, including those related to sexual assault (n = 50), assault (34), murder (28), robbery (18), fraud (13), and drug offences (13). Nevertheless, whether a suspect was ultimately guilty or not does not change the fact that misleading evidence was still present in these trials in the first place. ...
Evidence has the potential to be misleading if its value when expressing beliefs in hypotheses is not fully understood or presented. Although the knowledge base to understand uncertainties is growing, a challenge remains to prioritise research and to continuously assess the magnitude and consequences of misleading evidence in criminal cases. This study used a systematic content analysis to identify misleading evidence, drawing information from case transcripts of rulings argued unsafe by the Court of Appeal of England and Wales. In the 7-year study period, 218 applications were successful on appeal, containing 235 cases of misleading evidence. The majority (76%) of successful appeals were based upon the same materials available in the original trial, rather than the presentation of new relevant information. Witness (39%), forensic (32%), and character evidence (19%) were the most commonly observed evidence types, with the validity of witnesses (26%), probative value of forensic evidence (12%), and relevance of character evidence (10%) being the most prevalent combinations of identified issues. Additionally, the majority (66%) of misleading evidence types relate to their interpretation at activity level. The findings suggest that many of these misleading aspects could have been prevented by providing more transparency in the relationship between evidence and hypotheses. Generally, the results contribute to gaining a more complete picture of the role of misleading evidence in the criminal justice system.
... In order to address these questions, it is also necessary to consider how to extract diatoms safely and reliably from common footwear materials. There is, at present, no consensus on how best to extract diatoms for forensic purposes, neither for samples of fabric [38,39,42,43], or organic tissue [44][45][46]. No published research has specifically considered protocols for the extraction of diatoms from footwear. ...
... It was considered valuable to develop an alternative to the hydrogen peroxide method adapted from the environmental sciences [38,47] to ensure the ability to apply it to any footwear materialbeing a powerful oxidising agent, there is the potential for a combustible reaction when using hydrogen peroxide, especially when applying heat [48]. The ethanol rinsing method requires a shaker capable of generating turbulence [42,43], which was not available for this research. Accordingly, in this study, the hydrogen peroxide extraction method established by Scott et al. [38] (for the materials where this would not be hazardous) is compared with two novel techniques known to be safe with organic materials. ...
In recent years there has been growing interest in environmental forms of trace evidence, and ecological trace evidence collected from footwear has proved valuable within casework. Simultaneously, there has been growing awareness of the need for empirical experimentation to underpin forensic inferences. Diatoms are unicellular algae, and each cell (or ‘frustule’) consists of two valves which are made of silica, a robust material that favours their preservation both in sediments and within forensic scenarios. A series of experiments were carried out to investigate the transfer and persistence of diatoms upon common footwear materials, a recipient surface that has historically been overlooked by studies of persistence. The effectiveness of two novel extraction techniques (jet rinsing, and heating and agitation with distilled water) was compared to the established extraction technique of hydrogen peroxide digestion, for a suite of five common footwear materials: canvas, leather, and ‘suede’ (representing upper materials), and rubber and polyurethane (representing sole materials). It was observed that the novel extraction technique of heating and agitation with distilled water did not extract fewer diatom valves, or cause increased fragmentation of valves, when compared to peroxide digestion, suggesting that the method may be viable where potentially hazardous chemical reactions may be encountered with the peroxide digestion method.
... Collecting and analyzing diatom components of geo-forensic samples hold potential value in aiding forensic investigations. [16] Acid digestion procedures in diatom analysis have inherent limitations, as they may lead to the destruction of diatom structures during the treatment process. However, this study introduced a groundbreaking technique called Lefort aqua regia (composed of a 3:1 ratio of nitric acid to hydrochloric acid) for recovering diatoms from tissue samples. ...
Forensic Limnology, a specialized subdivision within forensic science, utilizes diatom analysis as an indispensable tool for investigating cases near water bodies. Diatoms, minute algae with intricately patterned siliceous shells, serve as vital ecological indicators, providing critical evidence in diverse forensic scenarios. This comprehensive review underscores the paramount importance of diatom analysis in cases involving drowning, suspicious deaths near water bodies, and bodies disposed of in aquatic environments. Innovative techniques, such as Lefort aqua regia and fluorimetry, significantly enhance diatom extraction and detection efficiency. Optimal clothing material selection, favoring cotton, acrylic, and viscose, profoundly influences diatom retrieval dynamics, optimizing trace evidence collection. Despite inherent limitations, meticulous adherence to standardized protocols ensures reliable and robust results. The cutting-edge Microwave Digestion-Vacuum Filtration-Automated Scanning Electron Microscopy approach showcases unparalleled precision in the estimation of postmortem intervals. Diatoms also function as invaluable geographical tracers, expertly aiding crime scene localization and facilitating meticulous tracking of individuals implicated in criminal investigations. While DNA barcoding holds immense potential in diatom identification, further database development remains imperative for widespread application. Inclusive case study demonstrates the diatom test's effectiveness in conclusively establishing drowning as the primary cause of death, bringing clarity to intricate forensic investigations. Diatom analysis within the field of forensic limnology emerges as an indispensable reservoir of invaluable evidence, notwithstanding its inherent limitations. Persistent advancements and seamless interdisciplinary collaborations hold the key to amplifying its potential, thereby fortifying justice-seeking endeavors and bestowing closure upon victims and their bereaved families.
... Once identified, it must be separated by the geologist and submitted to the specialistic analyses of forensic botanists and entomologists, respectively. In particular, the finding of plant remains such as seeds, thorns, leaves, and pollens or their associations have been demonstrated to be very useful for linking forensic evidence to a specific environment of provenance and for dating the period of transferring the trace [10,[93][94][95][96][97][98][99]. New advances in forensic biology on the vegetal DNA identification may demonstrate the transfer of Geosciences 2023, 13, 335 4 of 28 a specific plant DNA to an actor of crime. ...
Criminal investigations aiming to track the route walked by missing persons and fugitives (MPFs) usually involve intelligence analysts, military planners, experts in mobile forensics, traditional investigative methods, and sniffer dog handlers. Nonetheless, when MPFs are devoid of any technological device and move in uninhabited rural areas devoid of tele cameras and densely covered by vegetation, tracking the route walked by MPFs may be a much more arduous task. In the XVIII century, the expert Georg Popp was able to link a homicide suspect to a sequence of different sites of criminal interest, located in the countryside, by studying the stains of soils found on the footwear and trousers of the suspect. In such complex cases, a very efficient approach for tracking the route walked by MPFs may consist of comparing the geological traces found on the MPFs and their belongings with soils exposed in the event scenes. In particular, the search for peculiar or rare particles and aggregates may strengthen the weight of the geological forensic evidence comparisons. A match of mineralogical, textural, and organic matter data may demonstrate the provenance of the traces from the soil of a specific site, thereby linking the MPFs to the scene of events. Based on the above, the present paper reports geological determinations accomplished for a “mediatic” casework. The results allowed a general high degree of compatibility among traces collected on the MPFs and on the soil from the scene of events to be ascertained. The most significant positive matches, based on the finding of ten peculiar and rare particles and assemblages, allowed the reconstruction of a route about 1.1 km long, as the crow flies, on the event site. Although this procedure was extremely time consuming and available only in a backwards reconstruction linked to the MPFs’ findings, it was of uttermost importance in strengthening the inferences proposed, and for which other methods could not provide any information.
... The main parameters and characteristics investigated in the inorganic and anthropogenic fractions may be synthesized as follow (Table 1) The organic component, vegetal and animal, may be very abundant and important in the sample and once identified must be separated and submitted to the specialistic analyses of forensic botanists and entomologists, respectively. In particular, the finding of plant remains such as seeds, thorns, leaves, and pollens or their associations demonstrated to be very useful for linking evidence to a specific environment of provenance and for dating the period of transfer the trace [10,[93][94][95][96][97][98][99]. New advances on forensic biology on the vegetal DNA identification may demonstrate the transfer of a specific plant DNA to an actor of crime. ...
Criminal investigations aimed to track the route walked by Missing Persons and Fugitives (MPFs) usually involve Intelligence analysts, military planners, experts in mobile forensics, traditional investigative methods, and sniffer dog handlers. Notwithstanding, when MPFs are devoid of any technological device and move in uninhabited rural areas devoid of tele cameras and densely covered by vegetation, tracking backwards the route walked by MPFs may be a much more arduous task. In such complex cases, a very efficient approach may consist in comparing the geological traces found on the MPFs with soils and plants exposed in the event scenes. In particular, the search for peculiar or rare particles and aggregates may strengthen the weight of the geological evidence comparisons. A match of mineralogical, textural, and botanical data may demonstrate the provenance of the traces from the soil of a specific site, linking in this way the MPFs to the scene of events. Based on the above, the present paper reports geological and botanical determinations accomplished for a “mediatic” casework. Results allowed to ascertain a general high degree of compatibility among traces collected on the MPFs and on the soil from the scene of events. The most significant positive matches, based on the finding of a ten of peculiar and rare particles and assemblages, allowed reconstructing a route about 1.1 km long, as the crow flies, on the event site. Notwithstanding this procedure was extremely time consuming and available only in a backwards reconstruction linked to the MPFs’ findings, it was of uttermost importance in strengthen the inferences proposed, where other methods could not provide any information.
... Cameron stated in his research paper diatoms are diverse remains and can be identified with high taxonomic precession these factors also allow diatoms to be used in the range of application in forensic geosciences [17,18]. ...
Diatom is an important conclusive tool used in the diagnosis of drowning and dumping cases as the features pf postmortem changes disappear fast when the commencement of putrefaction appears hence diatom is reliable and conclusive test for the diagnosis of drowning diatoms have large number of characteristics feature species diversity and they can be preserved therefore this group can be used as geoforensic science for criminal investigation the temperature and ph. variation plays important aspects in distribution of diatoms at different locations the extraction and identification of diatoms present in tissues plays a role of supportive evidence in drowning at specific site a specific diatoms found in water and specific area of tissue give a reliable result for drowning hence proper measures and identification technique can be followed this paper follows an application of diatoms in forensic sciences.
... Diatoms provide a freely ecological assessment of forensic evidence in suspected in dumping and drowning cases, linking crime scene locations, sites of accidental or suicide. Only a short-term (e.g. the perpetrator leaving a crime scene) contact between clothing and water body can cause significant transfers of diatoms, which could be collected for analysis in a criminal investigation Scott et al. (2014) 11 . In this study a total 18 diatom genera were identified. ...
Diatoms are unicellular, photosynthetic (autotrophic), eukaryotic organisms often classified as among the algae. They are scientifically known as Bacillariophyceae. Diatoms study can be used in medico-legal purpose to solve the cases of unclaimed drowned or dumped bodies. The detection of diatoms in the organs can contribute to a diagnosis of death by drowning, a process referred to as the ‘diatom test’.This study was conducted in the department of Forensic Science, SHUATS, Prayagraj which included the extraction and identification of diatoms from the collected water samples from three different sites of Ganga River in Vindhyachal. The acid-digestion method was used for diatom extraction. 27 samples were collected (3 from each site) in the month of January, February, March 2022 from 3 different ghats of Vindhyachali.e Babu Ghat, Pakka Ghat, Diwan Ghat. Samples were taken from surface, 1 feet and 2 feet deep inside river. After examination and analysis total 18 genera of diatoms were found. The identified diatoms were of great ecological importance and plays an important role in criminal investigations related to pre-mortem or ante-mortem drowning deaths in Ganga river at Vindhyachal,district of U.P,India
... These applications include the matching of environmental samples with substances or materials that have been in contact with water and the investigation of drowning cases. It also includes locating and linking the area in which an underwater crime occurred [44]. ...
Forensic botany is the field of science that applies the knowledge, techniques, and study of plant science to legal matters. The term forensic botany proves that plants can provide forensic evidence, as various plant species occur in the environment, which is limited to specific geographic locations. Besides, every species has unique characteristics. Hence, these features make plants be useful evidence for solving criminal and civil cases. However, forensic botany remains an underutilized field in forensic casework. Furthermore, although most forensic scientists are familiar with methods for human identity testing, the use of the plant, animal, and insect evidence is yet unknown. This low knowledge is due to a lack of awareness by evidence collection teams, who do not necessarily know the importance of collecting botanical trace evidence. Therefore, this review article encompasses different sub-disciplines that come under forensic botany along with case reports and proper collection procedures of botanical evidence. Overall , this article gives the importance and applications of botanical evidence during criminal and civil case investigations.
... Literature on forensic diatomology mainly includes the case reports documenting the usability of diatoms for forensics as well as original, experimental papers showing how diatoms may be associated with the circumstances of the event. The intensive studies are also carried out on diatom detection and extraction techniques [43,[49][50][51]. Recently it has been proposed to improve the classical diatom test by applying more efficient extraction methods, based on the capacity of DNA molecules to bind silicon present in frustules [52][53]. ...
Forensic botany is a science that studies biological traces of plant origin with regard to their practical usefulness as evidence used in judicial proceedings. Among the disciplines of forensic botany, the following have the widest application: palynology, plant anatomy, diatomology, plant ecology and plant molecular biology. It has been shown that the knowledge of plants can be used to determine the connections between the alleged perpetrator, victim and crime scene. In practice, the methods of forensic botany have been used to identify locations where the hostages were held or the sites of concealment of a corpse, distinguish between the place of the incident and that where the victim was abandoned, identify the perpetrator, the cause and time of death, unravel drug distribution networks, clarify the circumstances of plant and animal smuggling as well as war crimes. Despite the fact that the suitability of forensic botany for determining the circumstances of criminal events has been repeatedly confirmed, this science remains largely underestimated and scarcely used. This article presents the current state of knowledge in the field of forensic botany, characterizes its specific disciplines, possibilities and limitations relating to the application of the methods of forensic botany in investigative practice as well as outlines the perspectives of its further development.
... The diatom examination was performed for their microscopic analysis. Scott et al. (2014) highlighted the efficiency of H 2 O 2 to study the extent of transfer of diatoms and their extraction from clothing. The section of 100% unused cotton T-shirt was immersed in the soil and water samples taken from sampling sites (aquatic and terrestrial), respectively. ...
Algae are eukaryotic photosynthetic organisms found in freshwater, marine, or brackish water. They are capable of surviving in harsh conditions such as in snow, deserts, hot water spring, and in mutual relationships with other organisms like lichens, making them as cosmopolitan species in environment. Algae play vital role in every aspect may it be as primary producers in food chain or fixing maximum amount of carbon dioxide in nature. But talking about applications of algae in this paper, we have focussed on Diatoms (class Bacillariophyceae) which are golden brown algae. Their ubiquitous presence, small size, and silicious frustule with peculiar ornamentation add uniqueness to their identity. Nowadays diatoms are considered as prime evidence in solving cases of drownings in the fields of forensics. Diatoms from the drowning site can tell about the physicochemical nature of environment and help in knowing the mode of death of a drowned victim. As during drowning, these small entities enter inside the body through body openings and once penetrated inside the body they get circulated and deposited in various organs till the victim dies. These penetrated diatoms are then recovered as evidence by various techniques and then their microscopic studies further help in their identifications. This helps in linking the crime scene and the victim during the investigation and thus helping the crime mystery of drowning to be solved. Because of their vast role in the drowning case investigation they are regarded as golden standards in the fields of forensics.
... Pollen grains can be recovered from soil, ropes and twines, clothing and fabrics, hair, and stomach contents [63][64][65][66] and have proven useful in a broad range of forensic cases such as murder [67][68][69], burglary [70], sexual assault [71], authenticity [72] and falsified medicinal products [73]. Similarly, diatoms are a eukaryotic, unicellular, golden brown microalgae most often encountered in naturally occurring water bodies and thus have been studied for forensic scenarios associated with freshwater environments [74][75][76][77], most widely explored as markers in drowning cases [78]. ...
Massively parallel sequencing (MPS) has revolutionised the field of genomics enabling substantial advances in human DNA profiling. Further, the advent of MPS now allows biological signatures to be obtained from complex DNA mixtures and trace amounts of low biomass samples. Environmental samples serve as ideal forms of contact trace evidence as detection at a scene can establish a link between a suspect, location and victim. Many studies have applied MPS technology to characterise the biodiversity within high biomass environmental samples (such as soil and water) to address questions related to ecology, conservation, climate change and human health. However, translation of these tools to forensic science remains in its infancy, due in part to the merging of traditional forensic ecology practices with unfamiliar DNA technologies and complex datasets. In addition, people and objects also carry low biomass environmental signals which have recently been shown to reflect a specific individual or location. The sensitivity, and reducing cost, of MPS is now unlocking the power of both high and low biomass environmental DNA (eDNA) samples as useful sources of genetic information in forensic science. This paper discusses the potential of eDNA to forensic science by reviewing the most explored applications that are leading the integration of this technology into the field. We introduce novel areas of forensic ecology that could also benefit from these tools with a focus on linking a suspect to a scene or establishing provenance of an unknown sample and discuss the current limitations and validation recommendations to achieve translation of eDNA into casework.
... Their extended use in forensics has been underutilized 9 with successful cases in other areas showing great potential 10 . These include connecting a suspect to particular aquatic location 11 and diatoms transferred to clothing 9 . ...
Diatoms are found universally in waters around the world. Some diatom species such as Asterionella formosa have a broad variation in seasonal abundance leading to the possibility that diatoms could constrain the time of year when an object was immersed in water. Here we apply this technique to the cold case of DB Cooper’s money. Nine years after the crime, six thousand dollars in three bundles were found on the shore of the Columbia River near Portland, Oregon. This burial site was ~30 km from his reported jump location which gave no apparent reason for the money to end up there. This study found diatoms on a recovered bill which indicates that the money was immersed before burial. The species mix found on the bills was compared to a test bill submerged in the Columbia River in November which was the timeframe for the crime. The Cooper bill contained diatoms from summer bloom species suggesting that the money was not directly buried dry and the immersion happened months after the late November hijacking. This finding rules out of a majority of current theories related to the crime and proposes diatoms as a feasible methodology to constrain seasonal timelines in forensics.
... Several studies have provided methodologies to extract more diatoms from different items. Scott et al. [23] used three methods to extract diatoms from cotton t-shirts that had been in contact with diatom-rich water and soil. They performed a correlation study on the diatom species and abundance in water samples, and investigated the effects of soaking duration on diatoms. ...
In forensic practice, it is difficult to determine whether a dead body in the water resulted from drowning or from disposal after death. Diatom testing is currently an important supporting technique for the determination of death by drowning and of drowning sites, even though it is a time-consuming and laborious task. This article reviews the development of diatom testing over the decades and discusses a new method for the potential application of deep learning in diatom testing.
... Developing a reproducible and repeatable method for the transfer of perfume between garments represents a major first step for the potential use of perfume analysis in forensic reconstructions. The transfer of trace evidence (including diatoms, pollen grain, powder and metal particulates) between clothing has been the focus of a number of studies [23,24]. However, to our knowledge, there is currently no method in the published literature for replicating the transfer of a fragrance between garments. ...
At present, the analysis of volatile organic compounds (VOCs) from fragrances is not employed in forensic science despite its potential as a form of trace evidence. Perfumes are used by many men and women on a daily basis, contain a large and diverse number of fragrances, and are invisible to the naked eye. Moreover, research on VOCs from human scent has shown that solid phase microextraction (SPME) with gas chromatography-mass spectrometry (GC-MS) is a robust method for the analysis of these odorous compounds. This enables insights into the transfer and persistence of the VOCs, which is a prerequisite for the use of a trace in forensic reconstructions. This thesis presents the development, optimisation, and validation of a SPME GC-MS method for quantification of VOC traces from clothing. The method created was robust and sensitive, allowing quantification of VOCs from clothing even when the fragrance mixture was diluted up to 1500 times. Experiments that addressed the transfer characteristics of fragrance VOCs demonstrated that fragrances can transfer from one fabric to another even when the contact times between fabrics is as short as 10 s, and even when the perfume was aged on the primary fabric for as long as 48 h before transfer took place. The nature of the fragrance transfer also depended on the fabric type, so that a clear discrimination was observed between the transfer that occurred from a cotton fabric swatch onto a natural (cotton) fabric and onto a synthetic (polyester) fabric. Further experiments considered the persistence of fragrances. The data generated indicate that the highest VOC amounts are generally obtained from recipient fabrics after shorter persistence times of up to 1 d, however VOCs were successfully quantified for persistence times of up to 4 weeks. Lower environmental temperatures resulted in higher recoveries for most VOCs, especially for short persistence times. These findings demonstrate that the optimal recovery of VOCs from clothing occurs when the fabric is kept at cooler temperatures and analysed soon after the fragrance transfer occurred. Therefore, given the ability to recover VOCs from fragrances from clothing, and the transfer and persistence characteristics of these VOCs, there is potential for fragrance to be used as a form of trace in forensic reconstruction approaches to address both source and activity level propositions.
... This context must be incorporated into the appraisal of each crime scene and the complexity of the multiple variables and their relationship to one another acknowledged. This is vital in order to establish the best approach for the collection and analysis of physical evidence and its interpretation in a specific case (Scott et al. 2014). ...
The central role of human cognition in forensic science and its effect on the interpretation of forensic evidence is being increasingly recognised within the forensic disciplines. It is clear that the concerns over expert decision-making and their vulnerabilities have not only been highlighted in recent key governmental reports, but also created a debate within the literature. This has, within recent years lead to a rise of empirical research focusing on the impact of cognitive biases in all stages of the forensic science process, highlighting that these vulnerabilities are not limited to a specific area of expertise. In forensic anthropology, the presence of cognitive bias, its impact, and how to mitigate its effects are still not fully empirically assessed or appreciated. This thesis seeks to unearth and understand the degree to which contextual biases are present in forensic anthropology, and present ways that can mitigate the impacts in biological profiling. This research addresses the effect of context within forensic anthropological analysis throughout the forensic science process (collection, analysis, interpretation,) through a series of experimental studies. The results of the experimental studies showed that context could have a powerful effect in visual assessments of skeletal remains in sex, ancestry and age at death. Furthermore, the findings also provided an important first step towards understanding the potential effects of initial exposure to irrelevant context at a crime scene in the excavations of skeletal remains, showing a potential for cascading bias on the subsequent assessment of the skeletal remains. An evidence-based approach for dealing with cognitive interpretation issues within the human identification field is presented. The findings of this thesis have contributed to the body of knowledge and provide empirical data that illustrate the benefits of developing a more holistic approach to forensic decision-making from crime scene to court within forensic anthropology and the wider forensic disciplines.
... Since the work of Pounds and Smalldon [19][20][21] who addressed the persistence of fibres, it has been well established that trace materials are dynamic and once transferred there is an initial rapid loss of material followed by a longer period of more gradual loss. Whilst studies concerning the transfer and persistence of traces have been undertaken (DNA [22,23], fibres [24], glass [25,26], paint [27][28][29], hair [30][31][32], sediments [33][34][35][36]), there is still a long way to go. ...
It has recently been established that volatile organic compounds (VOCs) successfully transfer between clothing even with a short contact of 10 s, highlighting the potential to use VOCs in forensic reconstruction scenarios, such as sexual assault cases. The mid and low volatility compounds transferred in greater amounts than high volatility compounds. This study presents empirical data addressing the persistence of transferred VOCs on clothing for the first time. A series of experiments were carried out to determine the persistence of VOCs on clothing for time periods of up 4 weeks, on natural and synthetic fibres, and at three different environmental temperatures. The data indicate that the highest VOC amounts are generally obtained for shorter persistence times of up to 1 d. Whilst high volatility compounds were not recovered in sufficient amounts to allow quantification, the four other transferred VOCs were successfully quantified for persistence times of up to 4 weeks. The persistence for mid-volatility compounds follows decay curve trends in line with those previously obtained for fibres, glass and pollen. When comparing the persistence of VOCs on a natural and a synthetic fibre, for a persistence time of 1 h, the transferred VOCs were retained on a natural fibre in higher amounts than on a synthetic fibre. However, for longer persistence times the concentration of VOCs was similar between the two fabrics. Lastly, lower environmental temperatures resulted in higher recoveries for most VOCs, especially for short persistence times. These findings demonstrate that optimal recovery of VOCs from clothing occurs when the fabric is kept at cooler temperatures and analysed soon after the fragrance transfer occurred, although VOC recovery was possible at higher temperatures and after longer persistence times. Given the transfer and persistence characteristics of VOCs from fragrance, there is potential for fragrance to be used as a form of trace in forensic reconstruction approaches.
... Some have argued that a disproportionate level of attention has been dedicated to subjective decision-making. It is argued that this preoccupation is preventing the forensic science domain from focusing on increasing the objectivity with which forensic science evidence can be interpreted, through a better understanding of the traces themselves [43] by, for example, carrying out empirical studies aimed at understanding the persistence and transferability of traces [44,45]. Others have responded by arguing that there is not, in fact, an overrepresentation of research into the factors that affect decision-making within forensic science, and that research establishing the existence and mitigation of cognitive bias, the impact of context, and the more objective use of trace evidence need not be mutually exclusive [46,47]. ...
There has been an increased engagement by researchers in understanding the decision-making processes that occur within forensic science. There is a rapidly growing evidence base underpinning our understanding of decision-making and human factors and this body of work is the foundation for achieving truly improved decision-making in forensic science. Such an endeavour is necessary to minimise the misinterpretation of scientific evidence and maximize the effectiveness of crime reconstruction approaches and their application within the criminal justice system. This paper proposes and outlines a novel six phased approach for how a broadening and deepening knowledge of decision-making in forensic science can be articulated and incorporated into the spheres of research, practice, education, and policy making within forensic science specifically, and the criminal justice system more generally. Phases 1 and 2 set out the importance of systematic examination of the decisions which play a role throughout forensic reconstruction and legal processes. Phase 3 focuses on how these decisions can, and should, be studied to understand the underlying mechanisms and contribute to reducing the occurrence of misleading decisions. Phase 4 highlights the ways in which the results and implications of this research should be communicated to the forensic community and wider criminal justice system. Lastly, the way in which the forensic science domain can move forwards in managing the challenges of human decision-making and create and embed a culture of acceptance and transparency in research, practice and education (learning and training) are presented in phases 5 and 6. A consideration of all 6 connected phases offers a pathway for a holistic approach to improving the transparency and reproducibility of decision making within forensic science.
... For the extraction of diatoms in cotton T-shirt soaked in water containing diatom, Scott (2014) treated sample of t-shirt with H շ O շ diluted by 30% and waited 3 hours in the hot water bath at 70°C and then centrifuged the solution at 1200 rpm (18). Since swaps were also cotton material, the same method was followed in swaps analysis and it was concluded that H շ O շ usage was highly appropriate in terms of diatom number and variety. ...
Objective: Diatom analysis is a valuable tool in forensic science and it is useful in diagnosis of drowning and determination of the drowning site. The basic principal of the “diatom test” in investigation of drowning is based on correlation between diatoms are present in the medium where the possible drowning took place and inhalation of water causes penetration of diatoms into the alveolar system and blood stream and consequently their deposition into brain, kidneys and other organs, like the bone marrow of large bones. There are various extraction methods that are used to isolate diatoms from water and tissues. Nitric acid digestion is a worlwide known method for the extraction of diatoms. In this study, instead of acid digestion method, colloidal silica gradient centrifuge method was used to extraction diatom and the advantages of this technique has been aimed to be discussed.
Materials and Methods: Therefore, 30 visceral and body fluid samples that have been obtained from corpses which were removed from the water and brought to the Council of Forencic Medicine to perform autopsy, were examined and diatom were obtained from samples of 19 cases. Moreover, the diatoms that were obtained from the swab samples taken from the outer body surfaces and the diatoms obtained from the visceral organs were compared.
Results: When the diatoms which were obtained from internal organs tissues and body fluids were evaluated numerically, it was seen that the diatoms that were obtained lungs were in high numbers and it was followed by pleural liquid...
... A number of methods have been developed over the years to determine mechanical asphyxia as a result of drowning [10]. Determination of the presence of diatom algae is one of the supplementary methods of diagnosis, not only drowning but sometimes the place of drowning [11][12][13]. The scientific community is constantly discussing the authenticity and reliability of the diatom test at drowning [14]. ...
Forensic medical diagnostics of drowning now is a difficult issue to resolve. Determination of diatom plankton with light microscopy is one of the supplementary methods for diagnostics of drowning. The disadvantage of this method is the use of concentrated acids to destroy the tissues of the organs, which greatly complicates, and sometimes precludes the detection of diatom plankton. In this case, the detection of other phytoplankton species in internal organs is treated as pseudoplankton, but does not have a diagnostic value. We have developed a sensitive and specific method of drowning diagnostics using a pair of specific oligonucleotide primers by the polymerase chain reaction (PCR) method to determine the presence of DNA of Cyanobacteria of the genus Microcystis, namely a fragment of the 16S rRNA gene in the tissues of mice and water samples in order to establish the fact and place of drowning. In order to evaluate the diagnostic value of this method, we conducted an experimental study to detect fragments of the 16S rRNA gene in mice tissues during drowning and post-mortem immersion. The amplification products were found in the tissues of heart, kidneys, liver, spleen, bone tissue, brain tissue, and lungs in case of drowning. During post-mortem immersion products of amplification are detected only in the tissues of lungs. The results indicate that the proposed PCR method is a potentially useful tool for diagnosing of mechanical asphyxia as a result of drowning.
... Seasonal variability has important implications throughout the different stages of a forensic investigation. Firstly, the laboratory methods used when attempting to recover diatoms from clothing and footwear surfaces should be as efficient and reliable as possible, to yield an optimal sample for comparison [15,20,21,49]. Furthermore, the forensic importance of a relatively sparse diatom transfer sample should be interpreted within an exclusionary framework [10]. ...
Environmental indicators are increasingly sought and analysed in a range of forensic reconstructions. Although the majority of casework and research studies are concerned with the criminal investigation of terrestrial habitats (soils, sediments, plants etc.), freshwater environments are also frequently encountered as crime scenes. As such, microalgae, particularly diatoms, may provide useful circumstantial trace evidence following their transfer to a victim or perpetrator. Diatom analysis is a relatively underused technique in forensic ecology, although an increased empirical research focus is beginning to recognise the evidential value of a transferred assemblage. This study aimed to examine three of the spatial and temporal variables known to influence the extent of an initial transfer of trace particulates, within the context of freshwater diatoms to clothing. A series of experiments were designed to consider the impact of recipient surface characteristics (clothing type), source environment conditions (seasonality), and morphological (type of diatom) variability, on the total number (no. per cm²) and species richness (total no. sp.) of an evidential diatom sample recovered from clothing. Nine commonly used clothing materials were immersed in a freshwater river at three times of year – the early and late spring and in the winter. Diatoms were recovered using a H2O2 extraction technique and examined microscopically. The results demonstrated that diatom transfer to clothing varies significantly, with a greater abundance and a higher species richness transferred to coarse woven surfaces including acrylic, linen, and viscose. Significantly fewer diatoms were transferred to clothing in the winter, in line with seasonal fluctuations in the source environment diatom community. Furthermore, variation in the relative abundance of particular diatom species was identified between clothing types, provisionally suggesting that morphological characteristics may also support or limit the transfer of material. These findings highlight that, although clothing may offer a valuable repository of freshwater diatom trace evidence, the interpretation of evidential material should be approached within an exclusionary framework. Thus, empirical data has been generated to develop evidence bases within forensic ecology, demonstrating some of the spatial and temporal factors which may contribute to or limit the transfer of evidence.
... To determine estimates of absolute diatom abundance, or valve density, the number of valves 181 counted within coverslip transects was used to estimate the total number present upon the 182 whole coverslip (0.5 ml) and then multiplied to per m 2 based on sample volume and rock area 183 sampled ( Scott et al., 2014). These extrapolations were averaged across rock scrub replicates 184 for each river site, with mean valves per m 2 underpinning all diatom abundance analysis. ...
Climate change poses a considerable threat to the biodiversity of high altitude ecosystems worldwide, including cold‐water river systems that are responding rapidly to a shrinking cryosphere. Most recent research has demonstrated the severe vulnerability of river invertebrates to glacier retreat but effects upon other aquatic groups remain poorly quantified. Using new datasets from the European Alps, we show significant responses to declining glacier cover for diatoms, which play a critical functional role as freshwater primary producers. Specifically, diatom α‐diversity and density in rivers presently fed by glaciers will increase with future deglaciation, yet β‐diversity within and between‐sites will reduce because declining glacier influence will lower the spatiotemporal variability of glacier cover and its associated habitat heterogeneity. Changes in diatom assemblage composition as glacier cover declined were associated strongly with increasing river‐bed stability and water temperature. At the species level, diatoms showed a gradation of responses; for example, Eunotia trinacria, found exclusively at river sites with high (≥ 52%) catchment glacier cover, may be affected negatively by ice loss. Conversely, seven taxa confined to sites with no glacier cover, including Gomphonema calcareum, stand to benefit. Nineteen (22%) taxa were noted as threatened, endangered, rare or decreasing on the Red List of Algae for Germany, with most at sites ≤ 26% glacier cover, meaning further ice loss may benefit these diatoms. However, six taxa found only in rivers ≥ 28% glacier cover may require reclassification of their Red List conservation status, as this habitat is threatened by deglaciation. Our identification of clear links between decreasing glacier cover and river diatom biodiversity suggests there could be significant reorganisation of river ecosystems with deglaciation, for example through alterations to primary production, biogeochemical cycles and the shifting resource base of alpine freshwater food webs which lack significant allochthonous energy inputs.
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... Trace material that has transferred can offer valuable information in forensic reconstruction to help identify contacts between objects, people, or locations [21]. Studies such as those by Scott et al. [22] and Bull et al. [23] have provided data that can begin to provide an empirical evidence base to understand the dynamics of various trace particulates, such as diatoms and pollen grains, in terms of how they can transfer and persist on clothing under forensic conditions. Despite the popularity of fragrances in modern societies, analysis of fragrance VOCs from clothing is not currently used in forensic analysis, but it could potentially be a useful tool to assess the likelihood of a contact between individuals. ...
An analytical method for the determination of trace amounts of volatile organic compounds (VOCs) relevant to the cosmetics industry was optimised, validated and employed for the analysis of commercial perfumes. The method used a combination of headspace solid phase microextraction (HS-SPME) and gas chromatography-mass spectrometry (GC-MS). In addition to fibre type, three different HS-SPME extraction conditions were investigated simultaneously, namely incubation time, extraction time and extraction temperature, using a central composite design in order to determine the optimal conditions for the extraction of VOCs of interest. The main figures of merit of the proposed method (calibration range, limits of detection and quantification, trueness and precision) were evaluated for six different VOCs in both natural and synthetic fibres in order to validate it and verify its capability for the proposed application. The validated method was applied for the analysis of traces of commercial perfumes from fabrics, and the VOCs of interest were successfully quantified. This simple, highly sensitive, and robust method has the potential to represent a powerful approach for forensic reconstructions where perfumes have transferred between individuals, such as during assaults and sexual assaults.
... Las particulares propiedades de la sílice biogénica de los frústulos la hace muy atractiva para su empleo en numerosos campos de investigación y otras actividades, con costos rentables para su cultivo y de fácil manipulación y obtención del ambiente; por ejemplo, en la fabricación de la dinamita para que su manipulación sea estable y no ocurren explosiones accidentales; a estos frústulos se les tiene como una fuente apreciable de nanomateriales, siendo usados en la nanotecnología, biotecnología, ciencias ambientales, biofísica, bioquímica, resaltando con especial énfasis biosilicificación, biomineralización, vehículos para la liberación de drogas, biosensores inmunológicos y ópticos, filtros, inmunodiagnóstico, alimentos para la acuacultura, laboratorio en un chip, metabolitos y biocombustibles (Mishra et al. 2017). En el campo de las ciencias forenses la presencia de los frústulos se puede emplear para la resolución de casos; por ejemplo, su detección en las trazas o restos de los calzados (suela, cuero) o vestimentas pueden resultar en una evidencia para la reconstrucción de un escenario forense (geociencia forense); asimismo, el hallazgo de las diatomeas en órganos o fluidos corporales de cadáveres aporta evidencias en un caso por ahogamiento (Scott et al. 2014, Coelho et al. 2016, Levin et al. 2017). ...
RESUMEN Se presentan comentarios y se complementan las ideas de un artículo de reciente publicación en la revista Saber [Saber. 29(3):340-347, 2017], acerca de la taxonomía y sistemática de los organismos eucariotas pertenecientes al reino Chromista, así como también de su importancia médico-sanitaria, económica y bio-ecológica. ABSTRACT Comments are presented and the ideas of a recently published article in the journal Saber are complemented [Saber. 29(3):340-347, 2017], about the taxonomy and systematics of eukaryotic organisms belonging to the Chromista kingdom, as well as their medical-sanitary, economical and bio-ecological importance.
... The porous silicon shows PL if the porosity is sufficiently high (Nirmal et al. 2010), and different species of diatoms show different origins of PL properties based on their structural composition (Tian et al. 2008). Owing to these properties, currently, these materials are used in various fields including optochemical sensors (De Stefano et al. 2005;Setaro et al. 2007;Lettieri et al. 2008), biophotonic and biosensing devices (Junfeng 2012;Rea et al. 2016), removal of heavy metal ions from water (Yang et al. 2012), forensic geosciences (Kirstie Scott et al. 2014), biosynthesis of metal nanoparticles (Jayashree et al. 2015), bioindicators (Bruno et al. 2015), drug delivery (Hongbo et al. 2013) and more. Due to no reported toxicity and the high stability and reusability of the biogenic silica material, currently, there is a high demand and need for such material in sensing applications (Jafar and Miguel 2011). ...
In the present study, an attempt was made to develop a proof of concept for the detection of nitroaromatic explosive derivatives through the photoluminescence (PL) quenching process using functionalized diatom frustules as a sensing platform. The diatom frustules are composed of nanostructured, highly porous biogenic silica material and emit strong, visible blue PL upon UV excitation. PL-active biosilica was isolated from the marine diatom Nitzschia sp. and was amine-functionalized to develop a sensing platform. Functionalized diatom frustules were further characterized using field emission scanning electron microscope and a series of spectroscopic methods. When nitroaromatic compounds were bound to the functionalized diatom frustules biosilica, the PL intensity from the functionalized biosilica was partially quenched due to the electrophilic nature of the nitro (–NO) groups. The quenching process confirmed the Meisenheimer complex formation and was investigated by using Fourier transform infrared spectroscopy and time-resolved photoluminescence studies. The developed platform was further evaluated for its sensitivity and specificity, and the limit of detection (LOD) of the assay was determined as 1 μM for a series of nitroaromatic explosive compounds. In conclusion, the developed sensing platform will have great utility in the development of on-site detection platforms for sensitive detection of warfare explosive nitroaromatic compounds from the environment.
... was then compared against control samples taken from the activity nodes. Scanning Electron Microscopy [33][34][35], binocular microscopy [36][37][38] and particle size analysis [39][40][41] were selected as frequently utilised analytical approaches for trace environmental samples in forensic enquiry. A Low powered Leica S6E L2 binocular microscope was used to identify mineralogy and other materials both in the control samples, and samples recovered from device components. ...
Fig. 1. Map detailing the locations of activity nodes within the simulated IED supply chain. Source location of Amazon plastic containers unknown. Build site and cache at same location, but on different parts of the site.
This article evaluates the criteria for diatom testing in forensic investigations, focusing on drowning cases. Diatoms, unicellular algae found in aquatic environments, are critical to the determination of drowning because water containing diatoms is inhaled during submersion. The primary objectives include defining the exact amount and type of tissue to be analyzed, expressed in terms of diatom concentration relative to tissue weight, and detailing the conditions under which water samples are collected to study the diatom flora at the site. In addition, the importance of accurately identifying diatom taxa and comparing them by unit weight is emphasized. To improve the reliability of diatom testing, the study discusses advanced methods such as microwave digestion, vacuum filtration, and automated scanning electron microscopy (MD-VF-Auto SEM), which offer higher sensitivity and specificity. The integration of DNA sequencing and deep learning techniques is explored, offering promising improvements in diatom detection and classification. These advances aim to reduce false positives and improve the accuracy of determining drowning as the cause of death. The article highlights the need for standardized protocols for diatom testing to ensure consistency and reliability. By incorporating new technologies and refining existing methods, the forensic application of diatom testing can be significantly improved, allowing for more accurate and reliable conclusions in drowning investigations.
Forensic Palynology has been shown to be effective in some cases around the world, and in countries that usually apply this technique, protocols have been developed in partnership with academic institutions. The premise that pollen and spores found in clothing of a suspect or victim may indicate crime geolocation has been tested in countries with more homogeneous vegetation and predominantly anemophilous pollination patterns. However, the feasibility of this technique in tropical settings is unknown due to the lack of landscape-clothing pollen transfer studies and the impact of predominantly entomophilous vegetation. This study evaluates the forensic potential of pollen, spores, diatoms and foraminifera retained in clothing and shoes as geolocation proxies after contact with a heterogenous landscape in southeastern Brazil. To simulate a crime route, three individuals walked along a trail starting at a beach, passing through restinga vegetation, reaching a mangrove forest. Residues were extracted from pants, shirts and shoes by washing and later treated with hydrofluoric acid and acetolysis for mineral and organic content removal, respectively. Diatoms were extracted with hydrogen peroxide and hydrochloric acid and foraminifera through filtration and flotation processes. The results show that these microtraces were found in the clothing and shoes worn during the simulation and indicated direct contact with landscapes such as beach and restinga vegetation, mangrove forest as well as fresh, brackish and seawater. This study suggests that the palynological technique can be added to Brazilian Forensic protocols used by scientific police forces as by other countries with similar environmental realities.
Whenever a dead body is discovered in any water body, the prime question to be dealt by a forensic pathologist is to determine whether the death is due to drowning or it is the result of disposal after death. It is challenging to determine the cause of death in such cases and to differentiate a death due to drowning or other reasons. Drowning signs like pale skin colour, occurrence of froth in mouth and nostrils are clearly apparent in recent deaths due to drowning, however, with the passage of time these signs tend to disappear due to prolonged immersion of the dead body in the water body and advancing decomposition process. In case of drowning, water aspirated by the person into his lungs ultimately enters the main blood stream via alveoli in addition to the other micro-organisms and small impurities present in the water. Forceful inspiration and expiration causes the development of microscopic tears in the alveolar wall and the micro-organisms and micro-particles travel through these microscopic tears into the blood stream and ultimately to multiple organ sites and get deposited in the capillaries of these organs. These particles include a group of algae, commonly known as diatoms which tend to remain in the biological tissues and organs for longer periods of time and play a significant role in the determination of death due to drowning.
The field of forensic biology is an ever-evolving and constantly developing field. It utilizes knowledge of biological concepts and practical approaches that assists in a legal investigation. Forensic biology serves as a significant discipline dealing with multifarious sub-disciplines such as forensic genetics, forensic serology, forensic anthropology, forensic botany, forensic entomology, forensic microbiology, etc. For examination of different biological evidences, bodily fluids, and cellular components related to humans, animals plant or micro-organisms that are encountered at the crime scene or are relatable to the concerned crime. From the development of amthropometrical science in the 1870s by Alphonse Bertillon for personal identification to the currently emerging and developing field of DNA fingerprinting and microbial patterns, forensic biology has provided novel approaches and improved methodology for collection, preservation and analysis of compromised evidences encountered at the crime scene. This chapter deals with the basic introduction of various sub-branches of forensic biology and their utilization in the field of forensic science. The chapter also describes various bodily substances such as hairs, nails, seminal fluid, teeth and botanical evidences such as wood, leaves, pollens, etc., that are generally encountered at the crime scene along with the techniques of their identification and segregation and application in the forensic context. A detailed approach of wildlife forensics, forensic entomology, forensic limnology and forensic mycology towards assistance in the criminal investigation has been elucidated in this chapter.
The most common application of diatoms in forensic science is the determination of drowning death. A body discovered from the water does not always mean that the death was caused by drowning. If the individual is still alive when they reach the water, diatoms will enter their lungs and cause them to drown. Circulation then transports the diatoms to distant regions of the body such as the brain, kidneys, lungs, and bone marrow. If the individual is dead when they enter the water, there is no circulation, and the transport of diatom cells to various organs is hampered by the absence of circulation, and diatoms cannot enter the body. It is possible to determine whether the drowning occurred ante-mortem or post-mortem. By detecting diatoms in tissue samples, the diatom test has emerged as one of the most essential tests in forensic science. Drowned bodies and water samples from potential drownings are typically sent to Forensic Science Laboratories for diatom detection. The acid digestion test has been determined to be one of the most effective ways for assessing cases of forensic drowning.
Forensic science is the application of science which provides relevant evidence against crime. It is a broad field which comprises a diverse array of disciplines that includes DNA analysis, fingerprint analysis, etc. to solving a crime. The diagnosis of drowning is one of the most difficult tasks in forensic practices, and consequently an enormous number of tests have been carried out to allow a confirmation. However, still, it is difficult to distinguish a drowning from other deaths. Diatom testing is recently an important supporting method to determine the death by drowning. Diatoms are most common type of phytoplankton, helpful in relating suspects and fatalities to crime sight in and around water. This chapter provides brief information about the use of diatoms in solving drowning cases and some case studies related to this, forensic limnology, and the opportunities and importance of diatom test. This also discusses the challenges and constraints in diatom-supported forensic investigations.KeywordsDiatomsForensicsDrowningDiatom test
Environmental trace evidence offers useful circumstantial intelligence to link persons and scenes of forensic interest. An increasing empirical research base is dedicated towards understanding the transfer and persistence dynamics of environmental indicators including pollen, soils, and diatoms, within a diverse range of experimental frameworks. This paper presents two discrete studies exploring transfer and persistence of soils and sediments on footwear and diatomaceous earth adhered to clothing in forensically pertinent scenarios. Variables including sediment type, foot position, clothing type, and body positioning were also explored throughout. Both experiments incorporated a field-based methodology during the sampling effort. Photographs were collected of an initial transfer sample and of a retained assemblage following hours, days, and up to one-week of wear, facilitating macroscopic assessment of trace evidence dynamics. All images were processed using accessible, open-source software before spatial analysis of evidence distribution within and temporal assessment (% retention) upon each evidential surface. The results highlighted consistent loss of transferred sediment from footwear with significantly greater retention of loamy clay soil than dune sand which was absent beyond 24 h of wear. Loss was not influenced by wearer gait but was more rapid from those areas of the shoe sole in direct contact with the ground. Diatomaceous earth was retrieved from all three clothing types tested after one week - significant losses of material occurred before 48 h with a consistent assemblage identified beyond this. Denim was significantly more effective than acrylic and fleece for diatomaceous earth retention and significantly more material was lost from clothing worn on the lower body. These findings highlight the value of using visual environmental markers and a macroscopic analytical approach during the investigation of environmental trace dynamics. The methodology offers a novel, non-destructive assessment of soil and diatom transfer and persistence, complementing more extensive laboratory-based examinations to ensure the development of a well-rounded research base within the forensic sciences.
Plants are a good source of biological forensic evidence; this is due to their ubiquity, their ability to collect reference material, and their sensitivity to environmental changes. However, in many countries, botanical evidence is recognised as being scientifically. Botanical evidence is not mostly used for perpertration, instead it tends to serve as circumstantial evidence. Plant materials constitute the basis, among others, for linking a suspect or object to a crime scene or a victim, confirming or not confirming an alibi, determining the post-mortem interval, and determining the origin of food/object. Forensic botany entails field work, knowledge of plants, understanding ecosystem processes, and a basis understaning of geoscience. In this study, experiments with mammal cadavers were conducted to determine the occurence of an event. The simplest criterion characterising botanical evidence is its size. Therefore, macroremains include whole plants or their larger fragments (e.g. tree bark, leaves, seeds, prickles, and thorns), whereas microscopic evidence includes palynomorphs (spores and pollen grains), diatoms, and tissues. Botanical methods allow for an analysis to be repeated multiple times and the test material is easy to collect in the field. Forensic botany can be supplemented with molecular analyses, which, although specific and sensitive, still require validation.
The focus of this research lies within the context of the forensic process and addresses a current debate within the literature for the importance and necessity of a growing body of empirical research to inform each stage of that process. This thesis presents three experimental studies addressing the recovery, transfer, and persistence of forensic traces. First, a novel gelatine-based collection medium was created, and a sampling method validated, for recovering explosive and drug residues from a wide range of porous and non-porous surfaces. Second, the first reported use of Instron’s ElectroPuls for application to forensic science is also presented, employing a reductionist approach to evaluate the individual impact of force, time, and rotation on the transfer of explosive and drug particulates. Third, a comparison of the dynamics of drug particulates on paper and polymer banknotes are presented, assessing the implications this might have on crime reconstruction approaches as more countries adopt polymer banknotes as legal tender. Based on the results, this thesis presents an effective method for inclusion in the tool kit which investigators can rely upon when tasked with the forensic collection and recovery of trace particulates. Additionally, the findings indicate that there is value for broader crime reconstruction endeavours in taking a reductionist approach when seeking to understand the mechanics of trace transfers. This can assist in creating simulation models where specific parameters can be adjusted for a given case in which the transfer of forensic materials may have occurred. Such datasets are valuable for modelling the movements of traces to enable more transparent and reproducible interpretations of pertinent trace materials in crime reconstructions.
Criminal activities have their footprints from time immemorial and nature of crime has drastically changed over a period of time. There is neither a geographical boundary, nor technical limitations. Moreover terrorist’s activities, drug trafficking eco-crimes, high-profile crimes, robbery hit and run cases, building collapse, petroleum products adulteration are some of latest forms of crimes. In last 20 years, scanning probe microscopes have emerged as an essential technique in various fields, and atomic force microscope (AFM) is most commonly used scanning probe technique which has shown its wide range of application in examination of various evidences encountered on crime scene. Major advantages of AFM involve its high resolution in three dimensions, and sample is not necessary to be conductive and it does not need to be operated within a vacuum. It helps in studying a large range of topographies and many types of materials can be imaged under it. Evidences such as blood, fibers, hair, soil, finger prints, gunshot residue, pollen, etc. found on crime scene at nano- or micro-level can be examined under AFM. The chapter describes applications of AFM with respect to its application in examination of evidences that can help in bringing justice.
Drowning is a form of asphyxia which is caused by submersion/immersion of the body in water or any other fluid that occurs due to the aspiration of fluid into air passages and is mostly accidental. The main question arises in the case of a body recovered from water is whether the individual was alive at the time he entered water. If a body is found in water is does not necessarily mean, that this person has drowned. The bodily external and internal findings are necessary in medicolegal investigation of drowning deaths. Drowning is difficult to determine and are often diagnosed by eliminating other potential causes of death whereas diatom test is significant for the concluding analysis of drowning deaths. Diatoms found inside the body may serve as corroborative evidence in the diagnosis of the cause of drowning death. It can be ascertained whether the drowning is ante-mortem or post-mortem. The diatom test considered as the only tool to examine drowning cases. The present study highlights some specific points to drag conclusive results in the investigation of deaths due to drowning.
High throughput sequencing is improving the efficiency of monitoring diatoms, which inhabit and support aquatic ecosystems across the globe. In this study, we explored the potential of a standard V4 515F-806RB primer pair in recovering diatom plastid 16S rRNA sequences. We used PhytoREF to classify the 16S reads from our freshwater biofilm field sampling from three stream segments across two streams in south-eastern Australia and retrieved diatom community data from other, publicly deposited, Australian 16S amplicon datasets. When these diatom operational taxonomic units (OTUs) were traced using the default RDPII and NCBI databases, 68% were characterized as uncultured cyanobacteria. We analysed the 16S rRNA sequences from 72 stream biofilm samples, separated the chloroplast OTUs, and classified them using the PhytoREF database. After filtering the reads attributed to Bacillariophyta (relative abundance >1%), 71 diatom OTUs comprising more than 90% of the diatom reads in each stream biofilm sample were identified. Beta-diversity analyses demonstrated significantly different diatom assemblages and discrimination among river segments. To further test the approach, the diatom OTUs from our biofilm sampling were used as reference sequences to identify diatom reads from other Australian 16S rRNA datasets in the NCBI-SRA database. Across the three selected public datasets, 67 of our 71 diatom OTUs were detected in other Australian ecosystems. Our results show that diatom plastid 16S rRNA genes are readily amplified with existing 515F-806RB primer sets. Therefore, the volume of existing 16S rRNA amplicon datasets initially generated for microbial community profiling can also be used to detect, characterize, and map diatom distribution to inform phylogeny and ecological health assessments, and can be extended into a range of ecological and industrial applications. To our knowledge, this study represents the first attempt to classify freshwater samples using this approach and the first application of PhytoREF in Australia.
Global environmental threats present a challenge to scientists and the public alike. Both the disappearance of species and the accompanying decline in biodiversity urgently require a multidisciplinary and interdisciplinary scientific approach. This in turn warrants the application of techniques historically restricted to human and veterinary medical diagnosis or forensic investigations. In particular, there exists an unprecedented opportunity for input by pathologists and the appropriate use of their modus operandi, including necropsy and the laboratory examination of samples. The application of pathological methods to wildlife work is outlined, with particular reference to the investigation of crime and the emergence of conservation forensics as a subject in its own right.
Soil forensics has proven instrumental in assisting criminal investigation, and there is an increasing demand for experimental studies on such trace evidence. Here we present the first detailed study on the influence of clothing materials in soil transfer. We adopt an experimental approach to test the transfer of five common UK soils to five different clothing materials. Our experiment is designed to represent victim or perpetrator contact with soil at the scene of a crime. We highlight the complex relationship between soil transfer and clothing material type. Whilst over half of our soils tested displayed differential transfer to different clothing materials, soil moisture content and soil type were found to have a greater influence on the transfer of soils overall. Soil transfer is typically more effective across all material types when soils are wet and saturated. However, we find the relationship between soil transfer and material type to be more complex when soils are dry, with a significant bias in soil transfer to fleece material, which we attribute to static attraction. Encouragingly, for the analysis of forensic soils recovered from clothing artefacts, each of the transfer experiments we conducted led to soil transfer to every tested material. We suggest that future empirical studies now focus on the persistence of soils over time to clothing materials after transfer has occurred, and the transfer and persistence of soil palynomorphs present within soils.
Preliminary results for combined extraction
The implications of the recent recommendations of the Law Commission regarding the use of admissibility tests have the potential to be far reaching for forensic disciplines that rely on the expertise of highly qualified expert witnesses. These disciplines will need a concomitant body of peer-reviewed experiments that provides a basis for the interpretations of such evidence presented in court. This paper therefore, presents such results from two experiments which were undertaken to address specific issues that were raised in cases presented in the British courtroom. These studies demonstrate that there is a variability in the persistence of Lily, Daffodil and Tulip pollen when exposed to high temperatures between 0.5 min and 1440 min (24 h). It was possible to identify all three pollen types after 30 min of exposure to 400 °C, and after shorter time frames the threshold for successful identification was 700 °C after 0.5 min for all pollen types tested and 500 °C for Daffodil and Lily after 5 min of heat exposure. Over longer time periods (18 h (1080 min)) the different pollen types were found to persist in a viable form for identification at 300 °C (Lily), 200 °C (Daffodil) and 50 °C (Tulip). These findings, albeit from a small sample of pollen types, provide empirical contextual information that would contribute to such evidence having sufficient scientific weight to meet admissibility criteria and be viable evidence for a court. These studies demonstrate the value in seeking pollen evidence from even such extreme crime scenes as encountered in vehicular fires.
This paper presents two experimental studies that deal with the spatial and temporal distribution of pollen grains within a room of a domestic dwelling. The findings concur with the preliminary work of Morgan et al. [1] and provide greater detail as to the behaviour of pollen grains within indoor locations that are pertinent for forensic investigations. The spatial distribution of pollen in a room exhibits strong distance decay trends, with the majority of pollen recovered within 0.8m of its source. The pollen was found to persist in increasing quantities during the time the flowers were in the room. This study also shows that 20days after the flowers were removed, 25-32% of the original pollen was still present within the room. The influence of disturbance was investigated and whilst areas of high disturbance were found to retain less pollen than undisturbed locations, the influence of the proximity to source was a more dominant factor. These findings have significant implications for forensic investigation protocols, particularly the collection and interpretation phases of trace evidence analysis. The distribution of pollen around a room ensures that viable sources of trace pollen are available for transfer if contact is made between a location in the room and a suspect. The persistence of pollen many days after the flowers have been removed from a room indicates that many rooms in domestic dwellings will have distinctive assemblages that reflect the history of the flowers that have been displayed within that room in the past, and that these assemblages will persist and therefore be available for transfer. These preliminary findings indicate that investigation by forensic palynology in indoor domestic settings may well be an underutilised technique that has the potential to provide accurate and valuable intelligence and evidence for forensic enquiry.
Three experiments were undertaken to establish the potential for forensic palynological analysis in cases of suspected document fraud. The first study tested 6 different types of paper and 9 different types of ink (n = 54) and it was established that the best retainer of particulates (in this case a proxy was used in the form of UV powder) was medium biro ink and Wove and Connoisseur paper. It was found that for the different paper types 42–52% of the particulates collected were found in the ink and thus both the paper and the ink are potentially valuable sources of trace evidence in a forensic investigation. The second study sought to address the differences in the spatial distribution of particulates on documents when writing took place before or after the paper was treated with UV particulates. Ninety-six observations were made for each piece of paper tested and it was found that when the writing took place after the particulates were applied to the paper; more particulates were retained on the paper in contrast to when the writing took place before the particulate treatment. The spatial distribution of particulates was also affected, with particulates being retained in the folds of the paper when the writing took place before particulate treatment in contrast to a more erratic pattern that emerged due to the pressure of the hand of the writer when the writing took place after the particulate treatment. The third study utilised lily (Lilium) pollen grains and the findings broadly concurred with the second study. The main difference identified was when the writing took place before the particulates were applied; when UV powder was used the particulates were retained in the folds of the paper whereas this pattern was not seen to the same degree when pollen grains were used due to their ‘stickier’ nature. Envelopes and the pen nibs were also found to be rich sources of pollen grains after the experiments were undertaken.
Benthic diatoms are the main component in many aquatic ecosystems such as streams, creeks and rivers, and they function as important primary producers and chemical modulators for other organisms in the ecosystems. In this study, the composition of benthic diatoms was investigated and further explored the primary physicals and chemicals affecting their temporal variations in the upper Han River, China. There were seasonal variations in physical and chemical variables in waters over the sampling period of 2007-2010. Water temperature (t), chemical oxygen demand, total nitrogen, dissolved organic carbon (DOC), silica and fluoride were much higher in the high flow season (i.e., July or August) than these in the base flow season. Three species Achnanthidium minutissimum (composed of 10.7 % of the total diatom abundance), Achnanthidium pyrenaicum (11.9 %), and Achnanthidium subatomus (12.7 %) accounting for more than 5 % of the total diatom abundance were persistently dominant in all seasons, while the other two prostrate and motile species including Eolimna minima and Nitzschia dissipata also dominant in the base flow season. The species richness always peaked in autumn with significant difference with summer (p < 0.01), and density of benthic diatom varied and peaked in April. Analyses indicated that the temporal variation in benthic diatom communities was strongly related to t, nitrogen, organic pollutants (indicated by COD and DOC), and hydrological regime. The research will expand the understanding of water chemistry monitoring, and improve watershed- scale management and conservation efforts in the upper Han River, China.
Diatom-based paleolimnological techniques were used to assess long-term changes in the water quality of Lake Simcoe (Ontario, Canada) using ²¹⁰Pb-dated sediment cores from four sites across the lake. Modest lake-wide shifts in diatom community composition occurred in the late 19th and early 20th centuries, suggesting that early cultural disturbances (e.g., land clearance and canal construction) had relatively minor effects on Lake Simcoe water quality. However, starting in the 1930s, phosphorus loading to the lake increased, which was closely tracked by increases in diatom taxa indicative of eutrophic conditions. The most pronounced lake-wide shift in diatom assemblages occurred in the mid- to late 20th century, the nature and timing of which strongly suggested a response to regional climate warming. An additional and marked lake-wide shift in diatom assemblages occurred in the mid-1990s, coinciding with the invasion of dreissenid mussels in Lake Simcoe. Our results indicate that Lake Simcoe water quality has been affected by the interaction of numerous environmental stressors over the past two centuries, the complexity of which has been amplified by recent warming.
DNA testing has exonerated over 200 convicts, some of whom were on death row. Studies show that a substantial number of these miscarriages of justice involved scientific fraud or junk science. This article documents the failures of crime labs and some forensic techniques, such as microscopic hair comparison and bullet lead analysis. Some cases involved incompetence and sloppy procedures, while others entailed deceit, but the extent of the derelictions - the number of episodes and the duration of some of the abuses, covering decades in several instances - demonstrates that the problems are systemic. Paradoxically, the most scientifically sound procedure - DNA analysis - is the most extensively regulated, while many forensic techniques with questionable scientific pedigrees go completely unregulated. The regulation of DNA profiling, which developed gradually over the last twenty years, can serve as a model for other laboratory units. The accreditation of crime laboratories, the certification of examiners, the standardization and promulgation of written protocols for each technique would go a long way in professionalizing forensic science. In addition, quality assurance programs, including proficiency testing and external audits, should be mandated. Finally, forensic science commissions should be established in every jurisdiction to implement these and other reforms.
Diatom, chrysophyte cyst, benthic cladocera, planktonic cladocera, and chironomid assemblages were studied in the surface sediments of 68 small lakes along an altitudinal gradient from 300 to 2350 m in Switzerland. In addition, 43 environmental variables relating to the physical limnology, geography, catchment characteristics, climate, and water chemistry were recorded or measured for each lake. The explanatory power of each of these predictor variables for the different biological data-sets was estimated by a series of canonical correspondence analyses (CCA) and the statistical significance of each model was assessed by Monte Carlo permutation tests. A minimal set of environmental variables was found for each biological data-set by a forward-selection procedure within CCA. The unique, independent explanatory power of each set of environmental variables was estimated by a series of CCAs and partial CCAs. Inference models or transfer functions for mean summer (June, July, August) air temperature were developed for each biological data-set using weighted-averaging partial least squares or partial least squares. The final transfer functions, after data screening, have root mean squared errors of prediction, as assessed by leave-one-out cross-validation, of 1.37 C (chironomids), 1.60 C (benthic cladocera), 1.62 C (diatoms), 1.77 C (planktonic cladocera), and 2.23 C (chrysophyte cysts).
Diatoms in clothing can be used to determine contact with surface water and contact with a specific water source, which can help link suspects to crime scenes. However, for the study of diatoms it is imperative that they are first extracted from the clothing under investigation. In this study we tested three methods for extracting diatoms from cotton clothing: rinsing with water (RW), rinsing with ethanol (RE) and the dissolution of cotton with nitric and sulphuric acid (DI). The DI method produced the highest average yield and can be used to determine contact with water. The RE method extracted reproducible numbers of diatoms from two different T-shirts and the resulting species compositions were similar to their relevant reference water samples. Therefore, we present rinsing with ethanol as an effective extraction method for the qualitative and quantitative analysis of diatoms in (cotton) clothing.
Automated geochemical techniques enable reproducible elemental assays of small quantity samples and have been used in recent years in many forensic criminal investigations in England and Wales. Two case studies are presented that highlight the problems of testing the presence of pre-, syn-, or post-crime event sample mixing. The number of elements or compounds analyzed can have a bearing on statistical discriminant techniques that may provide false-positive or false-negative associations or exclusions. Chemical analyses of soils and sediments using both atomic absorption spectrometry and Dionex (DX500 Sunnyvale, CA, USA), and inductively coupled plasma mass spectrometry enabled the identification and classification of discrete groups by hierarchical cluster analysis and canonical discriminant function analysis. These groupings, however, prove fragile to small variations within samples of even the most common minerals.
The rapidly expanding field of forensic geoscience derives its roots from nineteenth- and early twentieth-century scientists who both influence and are influenced by literature and fictional writing. Forensic geoscience borrows much, but not all, of its precepts from geological and geomorphological analytical techniques. Fundamental differences exist between forensic geoscience and its sister disciplines, fundamental enough to make the unwary geoscientist succumb to philosophical and practical pitfalls which will not only endanger the outline of their report, but may well indeed provide false-negative or false-positive results leading to contrary or inaccurate conclusions. In the law, such outcomes have devastating and untenable consequences. Forensic geoscience requires techniques of exclusion rather than inclusion and an acknowledgement that analytical techniques may be diagnostic only in very specific situations. Whether analysis of the ubiquitous or the exotic component is chosen, acknowledgement of the need for samples to be representative is required. The presentation of false-positive results or the lack of identification of sample ‘mixing’ is prerequisite to the application of statistical tests which must be applied in the most careful manner. The realization of the limitations of the technique requires, wherever possible, conjunctive analysis by other truly independent techniques. While personal opinion derives from experience, there is no place for assumption. Research papers in forensic geoscience are not submitted to be speculative or challenging as may be the case in many fields of geomorphology and geology. There is no place for conjecture in forensic geoscience.
The diagnosis of the cause and the establishment of the manner of death in submersion cases are routine challenge for forensic pathologists as it presents considerable diagnostic difficulties.
To concisely review the main questions during a submersion death investigation and to give the respective documented answers.
The search strategy included a literature search of PubMed, Medline and Google Scholar databases, as well as a review of the cited references by the identified studies and a hand search of relevant textbooks and reference works.
A complete autopsy, histopathological examination and full toxicological screening are important to determine whether death indeed followed submersion in the water, or to see whether any natural disease or substance use have contributed or caused death. In ambiguous situations, the co-estimation of circumstantial evidence may be of invaluable importance toward the conclusion concerning the cause and the manner of death. The thorough forensic investigation of the submersion deaths not only serves the justice administration, but it also presents considerable benefits for the public health.
One of the primary goals of forensic pathology is the determination of time of death. In aquatic systems, one method to do this is to analyze the colonization of a corpse by algae. Algal communities typically follow a serial colonization pattern, therefore the taxa present at any given time may provide clues about postmortem submersion time. This study was undertaken to examine the algal colonization on rat carcasses in a medium-order woodland stream. Two habitats were studied: a low flow pool and a high flow riffle, with rats being removed from each site every 3 to 6 days over 31 days. The diversity of colonizing taxa increased at both sites as the study progressed, and after 17 days similar taxa were present (Sorensen's similarity index >60%) in each site. Some taxa, such as desmids (Chlorophyta), tended to increase in diversity throughout the study, making them possible indicators of submersion time. Diatoms were the most abundant taxa found in each site and accounted for 63 of the 92 total taxa identified. Due to their ubiquitous presence in nearly all streams, we suggest that diatoms may be the key organisms for the study of postmortem submersion in lotic systems.
This case report shows how soil analyses (particularly petrology) can be used in conjunction with pollen in order to refine or strengthen an association. Soil samples from a car believed to have been used by the suspect in a missing persons case was subjected to soil and pollen analyses. The soil characteristics and petrology were used to redefine the search area using geology and soils maps, the pollen and vegetative remains were used to target woodlands with a particular species mix. As a result two bodies were located and the environmental evidence was used in the subsequent trial. In this case the history of the vehicle was well known and the wheel arches and footwells provided reliable soil traps. The advantage of combining the techniques is that soil evidence (both mineralogy and other inclusions) provides a geological/soils match while the pollen provides independent evidence of vegetation type providing a combination that may be rare or unique.
Results obtained by examination of 22 human cases suspected for drowning, one human case of death other than drowning and several tests on laboratory rats were used as a basis for evaluation of diatom method as supportive in forensic expertise of drowning. The recovery of diatoms from various examined organs, their qualitative and quantitative composition, if properly treated without the possibility of contamination, can be a reliable proof of the time and place of drowning. The priority of organ examination (external microflora determination, lungs, brain, heart (and/or blood), stomach, liver and kidney, and finally bone marrow) is discussed and established as well as the basic future research on cases suspected of drowning, but also on non-drowned victims and laboratory animals.
Introduction The legal process has used scientific procedures for many years in its various deliberations. Some of these, for instance DNA profiling of body fluids, are now essential and routine practice. The use of diatoms in forensic science is naturally much smaller, but in certain types of investigation, diatom taxonomy and ecology play a significant role. A diatomist may be able to provide investigations with evidence, which will enable the court to reach its verdict, and may be used by either the prosecution or the defence. Below we summarize some of the major applications of diatoms to forensic science.Drowning The most frequent application of diatoms in forensic science is in diagnosis of death by drowning. Drowning is a very common accidental cause of death, and thousands die each year in this fashion. The majority of these individuals die in circumstances that are not contentious, where there are witnesses, or strong indications of suicide, such as a note. Where circumstances surrounding an individual’s death are less clear, it is often important to be as certain as possible of how death occurred. Where a body is fresh, the pathologist may have little difficulty in reaching a verdict of drowning. However, the histopathological signs of drowning are often transient and overlaid by the grosser effects of decomposition. Additionally, in cases where an individual has been severely injured before being immersed in water, it is obviously important to determine whether death is due to these injuries or because of drowning.
Diatoms are unicellular, microscopic, photosynthetic algae with a distinctive cell wall made of silica. They occur in most aquatic habitats found on earth. In this article, an introduction to diatom biology and ecology is followed by a discussion of how they are commonly analyzed from sediments and how they have been used to provide quantitative inferences of past environments. Diatoms are numerous, diverse, frequently well preserved, and often have well-known ecological preferences. Consequently, there are a wide variety of applications in quaternary science which are described in the elsewhere in this encyclopedia.
During July, 1991, two young boys were brutally attacked by multiple teenaged assailants while fishing at a suburban Connecticut pond. After being accosted at knife point, the victims were bound with duct tape, beaten with a baseball bat and dragged into the pond to drown. One victim managed to free himself, rescue his colleague, and summon help from local residents. An exhaustive investigation led to the rapid apprehension of three suspects.
In an effort to link the suspects to the crime scene, sediment encrusted sneakers were seized from both assailants and victims, and analyzed for aquatic microorganisms. Numerous species of diatoms and scaled chrysophytes (planktonic algae) were recovered from the sneakers and from reference samples of pond sediment. The marked similarities in the algal communities present on the sneakers indicated exposure to a common freshwater habitat, most probably the crime scene pond. Additional analyses revealed that Mallomonas caudata was the dominant scaled chrysophyte species in each sample, and that there was no significant difference in the ratios of three species of the diatom Eunotia between all samples examined. These findings further supported the idea that all of the samples originated from a common, if not the same, locality. This case further exemplifies the applicability of aquatic community ecology to forensic investigations.
In an alleged rape case, the pollen content of soil samples from the suspect's clothing was compared with that of soil samples from the alleged crime scene (an alleyway) and from the alibi scene (next to a driveway) to determine whether or not the suspect had been at the alleged crime scene. Although only 7 m apart, the two scenes had significantly different soil pollen representations due to their different vegetation. Because of this close proximity, however, these differences in pollen representation were in the amounts of the same pollen types rather than in the numbers of different pollen types. The clothing samples showed a very strong correlation with each other and with the sample from the alleged crime scene in the amounts of pollen types present, very strongly supporting the contention that the suspect had been at the alleged crime scene.
The first paperback edition of the comprehensive text originally published in 1981 (see 82L/4502).-M.A.Bass
In a forensic investigation, the analysis of earth materials such as sediments and soils have been used as evidence at a court of law, relying on the study of properties such as color, particle size distribution and mineral identification, among others. In addition, the analysis of the organic composition of sediments and soils is of particular value, since these can be used as complementary independent evidence to the inorganic component. To investigate the usefulness of organic indicators in sediment characterization and discrimination, seventy-seven samples were collected during a period of one year in two river beaches located at the southern bank of the Douro River estuary in the North of Portugal. Isotopes of total carbon, pollen and plant wax-marker analyses were performed. In both beaches, an increase of the organic matter concentrations was noticeable, moving landward, related with the higher cover of associated plant material. The results obtained showed that the combination of all the techniques adopted showed a clear discrimination between samples from the two beaches, and also showed a differentiation of samples in relation to distance from the river in both beaches. The results also show that seasonality in these beaches was not a determining factor for discrimination, at the times considered. In addition, the effects of time was not marked.
Resistant compounds associated with vegetation have potential for understanding and uniquely describing soil. Although much of the forensic identification of soils has focused on the mineral component, this study illustrates how the origin of the organic component can be a useful tool in soil identification. The epicuticular wax of most plants contains mixtures of hydrocarbons (mainly n-alkanes) and plant species differences are persistent. Evidence from three separate studies is compiled to show the validity of this approach. In the first example, on upland grassland vegetation, the n-alkane pattern of the soil at one site reflected that of the overlying grass, whereas at another site, it reflected that of the previous vegetation, heather. In the second study, n-alkane analysis data indicated the presence of heather in a buried horizon, matching independent evidence from pollen identification. The third study was one covering the whole of Scotland, using an unbiased grid-sampling strategy. Results show that the patterns in the soil n-alkane profiles reflected the overlying vegetation. Where this was not the case, the profiles matched previously grown vegetation. Such biomarker information, derived from plant wax signatures, coupled with soil spatial information, has potential in the unique identification of soils.
Data from a regional soil survey in eastern England have been used to determine whether samples over the same parent material can be discriminated on the basis of both individual and multi-element geochemistry. Discrimination was based on estimates of measurement uncertainty, which were calculated from the analysis of a series of duplicates and subsamples. In the multivariate analysis we estimated a covariance matrix for the two sources of uncertainty and compared this to Mahalanobis distances calculated for pairs of samples within each parent material group. For 12 of the 19 individual elements, it was possible on average to discriminate between more than 80% of the samples within parent material groups and typically between 15 and 17 of the 19 elements discriminated individual samples. In the multi-element analysis, typically more than 99.8% of samples within the same parent material group were discriminated from one another. Hence, the geochemistry of a natural soil sample, when collected and analysed according to a strict protocol, and compared to a database that adopted the same methods, could be used to help establish provenance within bedrock-derived soil types. However, there are significant differences between the nature of soil samples and the way they are collected or derived in soil surveys and forensic investigations. These questions need to be addressed thoroughly before any practical application to forensic cases in which an investigator is attempting to link a suspect to a location based on soil geochemical signatures.
Panes of float glass were broken in order to study transfer and persistence of glass fragments on clothing: several breaking devices were tested (hammer, stone and pendulum). The experiments, including two persons, consisted in breaking a pane and wearing the clothing for variable periods of time t: one pane was broken for each experiment. The results show that the number of fragments transferred is highly variable. However some trends, confirming previous research, can be outlined: 1. The number of fragments transferred depends on the number of strikes and on the distance between the pane and the person standing nearby; 2. The number and size of the fragments retained depend on the period of time t, on the composition and/or weaving of the garment; 3. Even eight hours after breaking a glass pane it is possible to find as many as seven glass fragments.
1. Periphyton chlorophyll a (chl a), ash-free dry mass, taxonomic composition, and cellular and water-column nutrients were analysed every 4 weeks for a year at sixteen stream sites in New Zealand. The hypothesis was investigated that broad-scale differences in mean monthly periphyton development are defined primarily by the frequency of flood disturbances and the periphyton's interaction with the nutrients. it us of the streams as determined by catchment geology and land use.
2. Overall, mean monthly chl a concentration declined with increasing flood frequency (r= -0.711, P < 0.001), and seasonality in chl a was better defined at sites with a low frequency of floods. Chlorophyll a concentration was generally low throughout the year at sites with frequent floods (> 15 yr−1).
3. No relationship existed between inorganic nutrient concentrations and catchment geology or land development. However, conductivity declined significantly as a function of the percentage of the catchment underlain by nutrient-poor, hard rocks (plutonic and fine-grained metamorphic rocks) (r= -0.515, P < 0.05), but increased significantly with the percentage of the catchment in intensive agricultural land use (r= 0.799, P < 0.001).
4. Cellular nutrient concentrations suggested that nitrogen was the nutrient most commonly limiting periphyton production. In turn, cellular N concentrations declined significantly with increasing percentage of the catchment in hard rock (r= -0.5M, P < 0.05) and increased with percentage of the catchments in intensive agricultlural land use (r= 0.948, P < 0.001).
5.The sites were classified into three enrichment groups (high, moderate and low) based on their land use and underlying geology. Cellular N concentrations varied significantly among these enrichment groups (ANOVA F= 14.661, P < 0.001).
6. Log chl a decreased significantly with increases in the annual 80th percentile velocity. However, the relationship was significantly different among the enrichment groups.
7. A stepwise multiple regression on the full dataset identified that the frequency of floods, proportion of the catchment in high-intensity agricultural land use and proportion in alkaline rocks were the most significant factors explaining variation in mean monthly chl a among the sites (r2= 89%).
8. Overall, the results showed that flood disturbance and catchment enrichment regimes are probably the principal axes of the habitat template of periphyton among the study streams, and could be used to explain and predict broad-scale differences in periphyton development among other temperate stream ecosystems.
A procedure is described for making diatom microscopy slides from large numbers of sediment samples, simultaneously. The method uses small sediment samples, small test tubes, small amounts of hydrogen peroxide, no decantings, no centrifuging, and it requires no washing-up of glassware. It is, therefore, fast, cheap, gentle to the diatoms and needs little fume cupboard space.
Soil samples taken from and between consecutive shoeprints within a localized area were analyzed for pollen and compared with each other and with soil samples from the shoes that made the prints. The purpose was to establish the forensic value of using such samples to determine whether or not there is an association between people and crime scenes. This was done by determining the degree to which pollen assemblages in shoeprints in soil from within the same localized area differ, and the degree to which pollen assemblages in soil on shoes differ from assemblages in shoeprints in soil made by those shoes. The samples from and between the shoeprints showed a high degree of similarity, suggesting that pollen assemblages of such samples from within a localized area are homogeneous. A change in sampling depth from 1 mm to 20 mm did not significantly alter the pollen content of samples. The pollen content of the two soil samples from the shoes showed a close similarity to each other and to the soil samples from and between the shoeprints, indicating that pollen assemblages from soil on shoes do not differ significantly from assemblages in shoeprints in soil made by those shoes.
This paper provides our first forensic quartz grain surface texture analysis of soils from the southern hemisphere. Sediment and soil samples were collected from a simulated crime reconstruction in the environs of Canberra, Australia, which comprised a murder site, an alibi site and a body deposition site. Following the successful application of quartz grain surface texture analysis from many case locations in England1 and more recently in Switzerland2, this paper examines the potential for the application of this technique from areas around Canberra. The very specific geological history of the Australian continent provides new challenges for forensic reconstruction techniques. The quartz grain surface textural analysis undertaken indicates that clear differences between the three locations can be identified, enabling the successful differentiation of samples taken from the three distinct sites. This provides a means of undertaking exclusionary analysis and disproving an alibi location as being a possible source for material derived from the murder site or the body deposition site. These findings indicate that this form of geoforensic analysis has great potential for crime scene investigation of mixed-source physical trace geoforensic evidence in Australia. It also has the potential to provide an independent line of enquiry to other well established geoforensic techniques.
Quartz sand surface texture analysis has been automated for the first time for forensic application. The derived Basic Image Features (BIFs) provide computer-generated texture recognition from preexisting data sets. The technique was applied to two distinct classification problems; first, the ability of the system to discriminate between (quartz) sand grains with upturned plate features (indicative of eolian, global sand sea environments) and grains that do not exhibit these features. A success rate of grain classification of 98.8% was achieved. Second, to test the ability of the computer recognition system to identify specific energy levels of formation of the upturned plate surface texture features. Such recognition ability has to date been beyond manual geological interpretation. The discrimination performance was enhanced to an exact classification success rate of 81%. The enhanced potential for routine forensic investigation of the provenance of common quartz sand is indicated.
The persistence of wool and acrylic fibres has been studied on the surface of six representative articles of clothing during various periods of wear to a maximum of 34 hours. The initial rate of fibre decay was rapid for all the garments studied and the highest proportion of the original fibres which remained after 4 hours of wear was 18%. The rate of fibre decay was indistinguishable for wool and acrylic fibres on all garments studied. The three jackets and two sweaters despite the considerable differences in their construction and appearance, produced very similar rates of fibre decay. Fibres were lost at a significantly higher rate from a finely textured sports jacket and very rapidly from a cotton laboratory coat. In some of the experiments the length of fibres was recorded throughout, and the size distribution was found to be relatively constant during wear. This paper is intended to assist the forensic scientist with the interpretation of fibre evidence in those cases which involve fibre contacts, an area in which at present there is no documented knowledge. The possible mechanisms which could control fibre persistence on the surface of textile materials are briefly discussed.
Lakes systems respond physically, chemically and biologically to changes in climate and these responses are registered in many various ways in lake sediment records. This paper focuses principally on the biological record and describes recent research that aims to reconstruct (i) past variability in effective moisture, and (ii) past variability in temperature. Changes in effective moisture are manifested especially by changes in lake water level. In closed lake basins water level change can cause significant changes in water salinity that is registered in sediments by changes in the composition of fossil assemblages, especially diatoms. In open (freshwater) lake basins changes in water level are best reconstructed from the aquatic macrofossil record and potentially from the ratio of open water to littoral species of Cladocera, ostracods and diatoms. The most promising biological method for reconstructing past temperature is chironomid analysis, and a range of new chironomid-temperature transfer functions are being developed. However, biological responses to changing temperature are usually indirect as a result of temperature effects on water-column stratification, nutrient cycling and alkalinity generation, and in most cases a correct interpretation of the climatic significance of changes in the fossil record requires an understanding of the processes that are operating in the water column. A multi-proxy, whole-lake approach is advocated as the best way forward, not only as a means of reconstructing past climate but also as a means of assessing the impact of climate change on lake systems