Tatiana TrejosWest Virginia University | WVU · Forensic and Investigative Science
Tatiana Trejos
Ph.D.
About
78
Publications
30,274
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1,317
Citations
Citations since 2017
Introduction
Dr. Trejos is an Assistant Professor of the Department of Forensic and Investigative Sciences at West Virginia University. Dr. Trejos's primary area of expertise is forensic chemistry, with an emphasis on trace evidence, questioned documents, counterfeits, and gunshot residues.
Dr. Trejos's primary research interest includes the application of chemometrics to evidence interpretation and the solution of forensic problems using spectroscopy and mass spectrometry methods (SEM-EDS, ICP-MS, LA-CP-MS, u-XRF, LIBS, LC-MS-MS, GC-MS, FTIR). Tatiana has authored over 30 peer-reviewed scientific publications and book chapters and has contributed to the publication of international standard methods and guidelines. Tatiana received the Costa Rican National Academy of Sciences Award.
Additional affiliations
April 2013 - present
Position
- Director of Professional Science Master in Forensic Science
Description
- Instructor of Forensic Chemistry graduate courses, Hands-on graduate workshops on forensic science and hands-on workshops for forensic practitioners in trace evidence, instrumental analysis, CSI and forensic interpretation of trace evidence.
January 2013 - present
Position
- Assistant Director of Academic Programs
Description
- Applied chemometrics in trace evidence and characterization of materials of forensic interest by spectroscopic methods such as ICP-MS, Laser Ablation ICP-MS, u-XRF and Laser Induced Breakdown Spectroscopy.
April 2005 - January 2013
Position
- Coordinator of Research Programs
Description
- Characterization of chemical signatures of inks, paper, soils, paint, glass, chemical taggants, tapes and other forensic materials.
Education
August 2008 - November 2012
January 2002 - December 2003
Publications
Publications (78)
This study assists the interpretation of glass and paint evidence by filling an existing gap in the background occurrence that reflects the socioeconomic and demographic circumstances in the United States. The collection was performed in a college US city (Morgantown, West Virginia) to determine the effect of the type of clothing worn at different...
In this study, glass from 30 different portable electronic devices (PED) screens, 15 screen protectors (SP), and 3 brands of liquid glass (LG) were analyzed using a µ-XRF instrument equipped with two silicon drift detectors (SDD). Additional analysis of six fragments, all originating from the same PED and SP screen, assessed the elemental homogenei...
This study expands upon a previously developed method that quantifies the similarity of the compared tape edges by systematically studying the effect of several separation methods and tape grades on the quality of a fit. Analysts examined more than 3300 pairs of hand-torn or scissor-cut duct tapes from three different tape grades while they were ke...
Glass is a trace material commonly found at crime scenes that can provide valuable information at early investigative stages and during a trial. The forensic analysis of glass has steadily evolved since the 1970s with numerous technological advances in spectroscopy and spectrometry. This article presents an advanced review of the recent literature...
This study describes the use of single particle inductively coupled plasma time-of-flight mass spectrometry (spICP-TOFMS) for the detection and classification of inorganic gunshot residue (IGSR) particles. To establish reliable multi-element criteria to classify IGSR particles, leaded and lead-free IGSR reference materials were analyzed, and the el...
Micro X-ray Fluorescence Spectrometry (µXRF) is a well-established technique for the elemental analysis of glass in forensic casework. The standard test method for the forensic analysis of glass using µXRF (ASTM E2926) provides recommendations for the number of replicate measurements that should be collected to characterize a known source and the c...
Analysis of gunshot residue currently lacks effective screening methods that can be implemented in real time at the crime scene. Historically, SEM‐EDS has been the standard for analysis; however, advances in technology have brought portable instrumentation to the forefront of forensic science disciplines, including the screening of GSR. This study...
This study reports the prevalence of organic and inorganic gunshot residue (OGSR & IGSR) in various populations using emerging analytical methods. The survey includes over 3,200 samples from six subpopulations. The known shooter samples used various ammunition types: leaded (1), lead-free (2), and a mixture (3) collected as soon as the firearm was...
This work investigated the prevalence of organic and inorganic gunshot residue within two main subpopulations, 1) non-shooters, including groups with low- and high-risk of potentially containing GSR-like residues, and 2) individuals involved in a firing event (shooters, bystanders, and shooters performing post-shooting activities). The study analyz...
Portable Raman instruments provide quick, nondestructive analysis of organic and inorganic compounds, making it widely applicable in various disciplines. However, the instrument’s accuracy when analyzing pure, or multiple component mixtures is still an aspect that needs improvement. This study explored machine learning algorithms to classify single...
The results of an interlaboratory study by ten different laboratories using laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) and standard test method (ASTM E2927-16e1) for the analysis and comparison of glass evidence is reported. The aims were to evaluate the performance of the new CFGS2 calibration standard for the quantita...
This study evaluates the capability of μ-XRF and LIBS analyses to characterize the homogeneity (elemental variation) of glass compared to the LA-ICP-MS quantitative analysis method. Two premises in the forensic comparison of glass are that 1) the elemental composition across a single source (e.g., a pane) is homogeneous and 2) the elemental variati...
LIBS and LAICPMS microchemical mapping for rapid detection of gunshot residues is reported for a large dataset of pGSR authentic items and microparticle standards, with accurate differentiation between shooter and non-shooter profiles (>88%).
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Gunshot residue (GSR) refers to a conglomerate consisting of both organic molecules (OGSR) and inorganic species (IGSR). Historically, forensic examiners have focused only on identifying the IGSR particles by their morphology and elemental composition. Nonetheless, modern ammunition formulations and challenges with the GSR transference (such as sec...
Consensus concentration values for seventeen (17) major and trace elements typically present in soda-lime glass manufactured using the “float” process and used in the quantitative analysis and forensic comparison of glass samples were determined using laser ablation (LA) micro sampling coupled to inductively coupled plasma mass spectrometry (ICP-MS...
The forensic analysis of inorganic gunshot residues (IGSR) involves analytical measurements from samples taken from skin and other substrates. The standard practice for IGSR analysis recommends the use of Scanning Electron Microscopy-Energy Dispersive X-Ray Spectroscopy (SEM-EDS) to identify the gunshot residues using combined information of the pa...
Seventeen laboratories participated in three interlaboratory exercises to assess the performance of refractive index, micro X-ray Fluorescence Spectroscopy (µXRF), and Laser Induced Breakdown Spectroscopy (LIBS) data for the forensic comparison of glass samples. Glass fragments from automotive windshields were distributed to the participating labs...
This study describes the process of parameter optimization of an XRF method for casework use. The work expands upon previous discrimination studies by broadening the total sample set of characterized tapes and evaluating the use of spectral overlay, spectral contrast angle, and Quadratic Discriminant Analysis (QDA) for the comparison of XRF spectra...
The forensic examination of glass can provide information regarding the reconstruction of events, the type of glass involved in the case, and source commonality between a known and a questioned fragment. This chapter describes the main aspects of glass composition, manufacture, aftermarket distribution, transfer and persistence, and the scope of an...
The identification of counterfeit pharmaceutical packaging is a complex problem that often requires multiple physical or chemical analyses. In this study, LIBS and ATR-FTIR were used as fast and non-invasive methods to classify pharmaceutical paperboard packaging sample into an authentic group or belonging to one of five counterfeit counterpart pac...
The increasing demand for rapid methods to identify both inorganic and organic gunshot residues (IGSR and OGSR) makes electrochemical methods, an attractive screening tool to modernize current practice. Our research group has previously demonstrated that electrochemical screening of GSR samples delivers a simple, inexpensive, and sensitive analytic...
The aims of evaluating forensic evidence are to provide a transparent, coherent, and unbiased opinion of the value of the evidence to fact‐finders. Measurements from glass evidence in a hit‐and‐run, for example, can help decide if a particular vehicle was involved in the accident. The evaluation involves the comparison of the physical, optical, and...
In this paper, a review of the literature concerning the scientific foundations of trace evidence analysis is presented along with a discussion regarding the current challenges for the discipline. Information about the composition, manufacture, transfer, and persistence of trace materials are discussed with a focus on how each aspect impacts trace...
Physical fit examinations have long played a critical role in forensic science, particularly in the trace evidence, toolmark, and questioned documents disciplines. Specifically, in trace evidence, physical fits arise in various instances such as separated pieces of duct tape, torn textile fragments, and fractured polymeric items to name a few. The...
This study evaluated the use of Laser Induced Breakdown Spectroscopy (LIBS) as a fast spectrochemical detection method for gunshot residues analysis around bullet orifices in complex substrates. Two approaches were assessed; the first one was aimed at shooting distance determination on bloody fabrics and the second one provided a fast bullet hole c...
Presented is a review of scientific literature from the past two decades on the various aspects affecting deposition, persistence, and collection of organic and inorganic gunshot residue (OGSR and IGSR, respectively). With market changes in the manufacture of modern ammunition affecting typical elemental composition and morphology of particles, and...
This review paper covers the forensic-relevant literature in paint and glass evidence from 2016 to 2019 as a part of the 19th Interpol International Forensic Science Managers Symposium. The review papers are also available at the Interpol website at: https://www.interpol.int/content/download/14458/file/Interpol%20Review%20Papers%202019.pdf.
This study developed a reliable laser‐induced breakdown spectroscopy (LIBS) screening approach capable of detecting GSR in just a few minutes with minimal damage to the sample, high specificity, and sensitivity. Moreover, a novel micro‐sampling method was developed to gather three‐dimensional data of the simultaneous occurrence of IGSR markers from...
Duct tape is a common type material found at crime scenes such as sexual assaults, murders, kidnappings, and bombings. During the examination of a known and questioned item, a 3D realignment along their edges is known as a physical fit and is often regarded as conclusive evidence that the items were once part of a single object. The conclusion of a...
The aim of this work was to assess the utility of the infrared (IR) camera as an effective tool for observing physical features like soot and firearm discharge residues (FDR) around the entrance hole, to aid estimation of the shooting distances on bloody, dark and patterned samples. In this study, white control samples, as well as colored and patte...
Adhesive tapes are an important type of evidence related to violent crimes such as the construction of improvised explosive devices and kidnappings as well as involved in other types of common evidence such as drug packaging. The methods of comparison of tape evidence consist of physical and microscopic examination followed by chemical analysis of...
Learning Overview: The goal of this presentation is to show how the superior selectivity and sensitivity of Laser-Induced Breakdown Spectroscopy (LIBS) analysis, compared to color methods, will offer more reliable investigative information and more defensible results in court when a firearm is involved in a crime. Impact on the Forensic Science Com...
This study proposes the application of Laser-induced breakdown spectroscopy (LIBS) as a novel and practical method to detect gunshot residues around bullet holes and to estimate shooting distances in firearm-related criminal events. Clothing samples fired at different distance intervals were analyzed by LIBS, and the spectral data collected from th...
Elemental analysis of electrical tapes is typically conducted by Scanning Electron Microscopy-Energy Dispersive Spectroscopy (SEM-EDS), although Laser Ablation-Inductively Coupled Plasma – Mass Spectrometry (LA-ICP-MS) recently showed to enhance the sensitivity of the determinations. In this study, the utility of X-ray Fluorescence (XRF) is compare...
Documents are frequent targets of fraud and adulteration. Sometimes it is not enough to determine the document’s authenticity or authorship, but it is also necessary to demonstrate when the document was signed or written. Determining the age of a document, also known as ink dating analysis, is still a challenge for the forensic examiners. There are...
Information about the transfer and persistence of glass, as well as the frequency of occurrence of background glass in the general population, is key for the forensic interpretation of glass evidence. In this study, a mock case was designed to evaluate how glass shards are transferred during the breaking of a vehicle side (tempered) window, to what...
In this study, electrochemical and laser-based spectroscopic methods (LIBS) are proposed as screening methods that are quicker, more selective and more effective than any current field-testing technique. These methods offer superior information by simultaneous detection of organic and inorganic gunshot residues, including a substantial number of el...
This study applies Raman microspectroscopy to differentiate the chemical components in printing inks of different brands, colors, and type using the 532 nm and 785 nm excitation wavelengths. Spectra were collected from 319 inks (78 inkjet, 76 toner, 79 offset, and 86 intaglio) representing various colors. Comparisons were performed to calculate dis...
Adhesive tapes are commonly found as physical evidence in cases involving violent crimes and national security threats. This research evaluated the utility of Laser Ablation-Inductively Coupled Plasma-Mass Spectrometry (LA-ICP-MS) for the characterization of chemical signatures of electrical tapes for forensic comparison and provenance purposes. Th...
Laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) provides qualitative and quantitative measurements of the elemental and isotopic composition of materials that are of interest to forensic scientists. The technique can chemically characterize physical evidence associated with a crime event, a location, contact between objects...
A searchable printing ink database was designed and validated as a tool to improve the chemical information gathered from the analysis of ink evidence. The database contains 319 samples from printing sources that represent some of the global diversity in toner, inkjet, offset, and intaglio inks. Five analytical methods were used to generate data to...
Improvements in printing technology have exacerbated the problem of document counterfeiting, prompting the need for analytical techniques that better characterize inks for forensic analysis and comparisons. In this study, 319 printing inks (toner, inkjet, offset, and Intaglio) were analyzed directly on the paper substrate using scanning electron mi...
This chapter describes the progression and maturation of forensic analysis of glass from individual research efforts through interlaboratory trials and, ultimately, to the adoption of consensus methods. Scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS), X-ray fluorescence method (?-XRF), inductively coupled plasma methods (ICP-A...
Elemental analysis, using either LA-ICP-MS or LIBS, can be used for the chemical characterization of materials of forensic interest to discriminate between source materials originating from different sources and also for the association of materials known to originate from the same source. In this study, a tandem LIBS/LA-ICP-MS system that combines...
Micro X-ray fluorescence (μ-XRF) spectrometry using an energy dispersive X-ray (EDS) detector is capable of detecting certain major, minor, and trace elements that permit potential discrimination of glass fragments in forensic cases on the basis of differences in elemental composition. Often, elements used for discrimination are present at concentr...
Elemental analysis of glass was conducted by 16 forensic science laboratories, providing a direct comparison between three analytical methods [micro-x-ray fluorescence spectroscopy (μ-XRF), solution analysis using inductively coupled plasma mass spectrometry (ICP-MS), and laser ablation inductively coupled plasma mass spectrometry]. Interlaboratory...
Four interlaboratory tests were designed to evaluate the performance of match criteria for forensic comparisons of elemental composition of glass by μ-XRF, solution nebulization SN-ICP-MS, LA-ICP-OES and LA-ICP-MS. A total of 24 analysts in 18 laboratories participated in the tests. Glass specimens were selected to study the capabilities of the tec...
Detection and sourcing of counterfeit currency, examination of counterfeit security documents and determination of authenticity of medical records are examples of common forensic document investigations. In these cases, the physical and chemical composition of the ink entries can provide important information for the assessment of the authenticity...
The method development for the use of LIBS in the analysis of glass, paint, plant matter, paper and ink will be described along with the observed figures of merit and compared to the more mature Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS).
This article describes the applicability of a rapid laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) method for the analysis of soil and sediment samples with broad chemical and physical properties and the comparison of its analytical performance to digestion protocols commonly used in environmental sciences. Two sets of samp...
Current methods used in document examinations are not suitable to associate or discriminate between sources of paper and gel inks with a high degree of certainty. Nearly non-destructive, laser-based methods using laser induced breakdown spectroscopy (LIBS) and laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) were used to impr...
The application of laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) to the elemental analysis of forensic matrices offers many advantages for solid sampling, including direct characterization of solids, the elimination of the need for chemical procedures for dissolution, minimal sample consumption, and a reduced risk of conta...
Improvements in mass spectrometry (MS) have greatly contributed to the advances in inorganic forensic
analysis, particularly in the area of trace evidence examinations. Analytical methods that offer superior sensitivity,
precision, and accuracy are valuable tools that assist the forensic community to expand their capabilities
of presenting more con...
A simple, rapid and sensitive method was developed for the routine analysis of trace elements on sediments and soils by UV-ns-LA-ICP-MS. The homogenization procedure that reduces the particle size of the samples to less than 1 µm diameter was found to be a key factor to allow for a representative sampling of the bulk soil at the micro-scale and to...
Forensic laboratories routinely conduct analysis of glass fragments to determine whether or not there is an association between a fragment(s) recovered from a crime scene or from a suspect to a particular source of origin. The physical and optical (refractive index) properties of the fragments are compared and, if a "match" between two or more frag...
Advances in technology provide forensic scientists with better tools to detect, to identify, and to individualize small amounts of trace evidence that have been left at a crime scene. The analysis of glass fragments can be useful in solving cases such as hit and run, burglaries, kidnappings, and bombings. The value of glass as "evidentiary material...
The analysis of glass fragments can be useful in solving cases such as hit and run, burglaries, kidnapping and bombings. Although refractive index has been routinely used for the analysis and comparison of glass fragments for some time, the forensic community has recognized the limitations of using this technique-by itself-for the association of gl...
The element analysis of glass samples for forensic use has been an interest in our group at Florida International University for over eight years as glass evidence can provide a way of associating a suspect to a crime Laser ablation has been incorporated in our analytical scheme due to the many advantages that solid sampling holds over digesting of...
The elemental analysis of glass samples for forensic use has been an interest in our group at Florida
International University for over eight years as glass evidence can provide a way of associating a
suspect to a crime. Laser ablation has been incorporated in our analytical scheme due to the many advantages that solid sampling holds over digestion...
The analysis of glass fragments can be useful in solving cases such as hit and run, burglaries, kidnapping and
bombings. Although refractive index has been routinely used for the analysis and comparison of glass fragments for some time, the forensic community has recognized the limitations of using this technique –by itself- for the association of...
Forensic analysis of glass samples was performed in different laboratories within the NITE-CRIME (Natural Isotopes and Trace Elements in Criminalistics and Environmental Forensics) European Network, using a variety of Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS) systems. The main objective of the interlaboratory tests was...
The authors have previously reported the use of laser ablation ICP-MS as a powerful analytical tool for elemental analysis of glass. LA is a simpler, faster and less intrusive sample introduction method than the conventional solution ICP-MS. Due to the minute amount of material removed in LA (∼300 ng, 50 μm crater size), the analyst should be aware...
Glass fragments recovered from crime scenes are usually very small and therefore the amount of sample available to conduct forensic analyses is limited. Elemental analysis using conventional digestion methods consumes at least 2-3mg of glass per replicate. LA-ICP-MS requires 10,000 times less glass consumption per analysis ( approximately 280ng), a...
Laser ablation (LA) is a powerful analytical technique for solid microsampling. Its coupling with ICPMS has been shown to offer good precision and accuracy for the elemental analysis of glass fragments. Fractionation in LA poses one of the major challenges to using this technique for in situ trace elemental profiling of glass evidence. The aim of t...
The importance of glass and paint evidence to associate a forensic event is discussed, using trace elemental analysis by solution ICP-MS. The technique of ICP-MS employed laser ablation (LA) solid sample introduction for the trace elemental analysis. The advantages of laser ablation include the simplification of sample preparation to reduce time an...
The discrimination potential of Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS) is compared with previously reported solution ICP-MS methods using external calibration (EC) with internal standardization and a newly reported solution isotope dilution (ID) method for the analysis of two different glass populations. A total of...
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Projects
Projects (3)
The overall goal of this proposal is to contribute to the advancement of the trace evidence discipline, by developing a practical approach with empirically demonstrable basis to assess the significance of fracture fits. The proposed strategy is building upon the existing literature, feedback from practitioners, and our own experience from pilot studies.
the overall goal of this study is to obtain baseline data of the frequency of occurrence of glass and paint relevant to the U.S. territory. This project will address essential factors never evaluated before in a single and systematic study: a) information of random presence of glass and paint fragments in different metropolitan and rural areas in the United States; b) sampling from common apparels; c) sampling at high traffic locations with diverse socioeconomic and demographic conditions; d) different seasonal-related fashion; and e) full characterization of features of interest of the recovered traces by appropriate analytical techniques.
Our overall purpose is to develop a comprehensive approach for fast and accurate identification of OGSR and IGSR to enhance current capabilities in the criminal justice system. This project aims to develop and validate fast tests—LIBS and electrochemical sensors—for FDR detection and statistical models for the quantitative interpretation of the evidence.