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In the past century, forensic investigators have universally accepted fingerprinting as a reliable identification method, which relies mainly on pictorial comparisons. Despite developments to software systems in order to increase the probability and speed of identification, there has been limited success in the efforts that have been made to move away from the discipline's absolute dependence on the existence of a prerecorded matching fingerprint. Here, we have revealed that an information-rich latent fingerprint has not been used to its full potential, as the content, in our approach namely the amino acids, present in the sweat left behind - can be used to determine physical attributes, such as gender, of the originator. Here, we are able to focus on the biochemical content in the fingerprint using a specially designed extraction protocol coupled with a biocatalytic assay for determining gender rather than focusing solely on the physical image.
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Forensic Identication of Gender from Fingerprints
Crystal Huynh, Erica Brunelle, Lenka Halámková, Juliana Agudelo, and Jan Halámek*
Department of Chemistry, University at Albany, State University of New York, 1400 Washington Avenue, Albany, New York 12222,
United States
ABSTRACT: In the past century, forensic investigators have universally accepted
ngerprinting as a reliable identication method, which relies mainly on pictorial
comparisons. Despite developments to software systems in order to increase the probability
and speed of identication, there has been limited success in the eorts that have been made
to move away from the disciplines absolute dependence on the existence of a prerecorded
matching ngerprint. Here, we have revealed that an information-rich latent ngerprint has
not been used to its full potential. In our approach, the content present in the sweat left
behindnamely the amino acidscan be used to determine physical such as gender of the
originator. As a result, we were able to focus on the biochemical content in the ngerprint using a biocatalytic assay, coupled with
a specially designed extraction protocol, for determining gender rather than focusing solely on the physical image.
In modern criminology, ngerprints play a major role in
forensics as a means of identication.
In the past 110 years,
the development of ngerprint analysis has stalled at simple
visual comparison and matching, even though ngerprintsas
samples of biological origin analogous to other body uids
have the potential to provide much more information.
Currently, the shape, size, and unique patterns associated
with ngerprints are compared using various computational
programs, such as Automated Fingerprint Identication System
(AFIS). However, the ultimate setback is the requirement of
matching ngerprints to be stored in a database or for the
person of interest to be physically present for comparison. If
neither of these conditions is fullled, the print is reduced to
merely exclusionary evidence,
despite being stored in a
separate database for future use when comparing them with
new, incoming ngerprints. The same can be said about DNA
analysis. Even though DNA can provide potentially the most
signicant information about the ngerprint originator, DNA
analysis can take weeks or months to be processed, and if there
is no matching DNA prole in the database, then the potential
for information is signicantly reduced. The purpose of our
approach is to address the issue of a ngerprint not having an
immediate matching image or DNA prole. While the patterns
of individual ngerprints, as well as DNA, act as important
sources of evidence, it is often overlooked that sweat and
sebum are also left behind with a ngerprint. Sweat contains
varying amounts of metabolites produced by the body
depending on various processes related to metabolism.
Metabolism, which is directed by a combination of multiple
hormone-based control mechanisms,
acts as a function of
physical properties such as gender, age, ethnicity, or health
status. It is also known that the amino acid content of an
individual can slightly vary depending on the physiological state
of the individuals metabolism. This slight variation occurs over
time scales of several hours and can also be somewhat aected
by certain medications
as well as after the consumption of
certain foods. It has been found that amino acid levels dier
between people in dierent demographic groups such as gender
(i.e., male and female).
As a result of this dierence, the
biological/biochemical content from the sweat left behind with
ngerprints can be exploited, in a method similar to the way
clinical diagnostics uses other body uid contents,
to gain
valuable information on dierent persons of interest
connected to a particular crime scene.
In fact, research has already started in this area using
spectrometric methods such as matrix-assisted laser desorption
ionization (MALDI) and liquid chromatographymass spec-
trometry (LCMS) as well as spectroscopic methods including
infrared and Raman spectroscopy.
Two examples of this
research involve the use of desorption electrospray ionization
(DESI) mass spectrometry to detect various explosive-related
and Raman spectroscopy to detect drug
compounds in the secretions left behind with ngerprints.
At the moment these methods require rather sophisticated
instrumentation that do not always allow for on-site analysis,
despite their incredibly selective and reliable nature. These
devices also demand highly specialized personnel that are not
likely to be available as part of the immediate forensic
investigation team. In addition, recently published eorts
using nanostructured materials and anity-based techniques
aim for the detection of compounds such as cotinine
in the latent ngerprint content. Notably, there has
been progress in the use of various instrumental studies on
latent ngerprints as demonstrated by the Kazarian group.
They have performed studies in spectroscopic
and chemical
of latent ngerprints. The possibility of using the
endogenous compounds in ngerprints for the determination
of various personal attributes has also been noted by other
instrumental chemists.
The vast majority of these methods,
however, can only focus on the presence or absence of certain
Received: August 30, 2015
Accepted: October 13, 2015
© XXXX American Chemical Society ADOI: 10.1021/acs.analchem.5b03323
chemical compounds. While this can be useful, there is still a
limit to the conclusions that can be drawn based on these
Despite the success in dierentiating between genders using
ridge density, a complex statistical analysis as well as visual
comparison by counting the number of ridges present in a 25
mm2area that are present is still required.
We have recently
demonstrated that bioanity-based analytical systems are able
to distinguish between African-American and Caucasian
ethnicities by analysis of biomarkers commonly present in
This was followed by a similar study that showed it is
also possible to distinguish between males and females.
very recent example
of the success of these bioanity systems
involves the parallel analysis of two blood markers in order to
determine age of the blood sample found at a crime scene.
Because the contents of ngerprints can provide information in
a way that is analogous to the contents of body uids, it should
also be able to provide information similar to the previously
mentioned study. In this work, the proposed methodology
utilizes the bioanity interaction between an enzyme and its
ligand (for example, substrate, cosubstrate, activator, inhibitor,
etc.) in order to generate a visible color change that can be seen
by the naked eye or spectroscopically quantied. The
extraction/bioassay system presented here is the rst proof-
of-concept example of a system that can detect a physical
characteristic of the ngerprint originator (male/female origin)
based on the chemical content of the ngerprint, ignoring the
traditional pictorial approach.
Ethics Statement. The Institutional Review Board, Oce
of Pre-Award and Compliance at the University at Albany has
fully approved the experimental protocols demonstrated in this
manuscript. These protocols were carried out in accordance to
the oces requirement of obtaining informed consent, in the
form of a signature from each volunteer, acknowledging that
they are aware of the procedure that will take place, any risks or
benets that may accompany the study, as well as acknowl-
edging that they will not receive any payment for their
participation. Informed consent from all volunteers who
participated in this research study was obtained.
Enzymatic Assay Components. The following enzymes
and organic/inorganic chemicals were purchased from Sigma-
Aldrich: L-amino acid oxidase type IV (L-AAO, E.C.,
horseradish peroxidase type VI (HRP,, o-dianisidine,
(+)-sodium L-ascorbate, triethanolamine (TEA), L-aspartic acid,
L-threonine, L-serine, L-glutamic acid, L-asparagine, L-glutamine,
L-cysteine, L-proline, glycine, L-alanine, L-valine, L-cystine, L-
methionine, L-isoleucine, L-leucine, L-tyrosine, L-phenylalanine,
β-alanine, L-ornithine, L-lysine, L-tryptophan, L-histidine, L-
arginine, and L-citrulline. Water used in all of the experiments
was ultrapure (18.2 MΩ·cm) water from PURELAB ex, an
ELGA water purication system.
Detection of Amino Acids. The dual-enzyme cascade,
displayed in Scheme 1, was designed and optimized in the
present study and realized in pH 7.6 TEA buer containing 20
mU of L-AAO, 3 U of HRP, and 85 μMo-dianisidine. The
cascade is activated when L-AAO reacts with a range of
concentrations of amino acids present in the sample, which
results in the conversion of O2to H2O2. The HRP then
consumes the H2O2, causing the oxidation of the dye, o-
dianisidine, present in the system. This results in the formation
of the oxidized form of o-dianisidine, which is observed
spectroscopically at λ= 436 nm. The intensity of visible color
production is then proportional to the amino acid concen-
trations present in the sample. This enzyme cascade was rst
optimized using mixtures of the average amino acid
concentrations specic for males and females, respectively.
The reactions and optical measurements were performed at 37
°C using a SpectraMax Plus384 (Molecular Devices, CA)
microplate reader with polystyrene (96 well) microtiter plates.
The signal corresponding to the concentration of oxidized o-
dianisidine was measured optically at λ= 436 nm.
Statistical Analysis. R-project software
was used to
generate randomized concentrations of each of the amino acids
found in ngerprint content to create 50 amino acid mixtures,
with 25 mixtures representing male samples and 25 mixtures
representing female samples. The L-AAO/HRP biocatalytic
assay was then performed using the 25 mimicked male and 25
mimicked female ngerprint samples. Receiver operating
characteristic (ROC) analysis was used to evaluate the
performance of the assay and estimate the probability of
distinguishing between the male (25 samples) and female (25
samples) groups of human ngerprint content. Using ROC
analysis, the threshold (above which the absorbance changes
correspond to the female group) that yielded the maximum
accuracy was determined. ROC analysis involves changing the
threshold and observing the eect on the predictive power of
the model to produce an ROC curve. The area under the ROC
curve (AUC) is a single measurement that summarizes the
overall discriminating ability of the assay. It represents the
probability that the diagnostic test will correctly distinguish
between the male and female samples. The larger the AUC, the
higher the probability that each sample will be identied
correctly. Lastly, to demonstrate the viability of this method,
real ngerprints were analyzed using the bioassay.
Amino Acid Extraction from Authentic Fingerprints.
For the purpose of determining the viability of the biocatalytic
assay when used with authentic samples, real ngerprint
samples were collected from volunteers and the amino acids
were extracted with a new protocol that was developed during
this project. This protocol combines the use of an elevated
temperature and acidic conditions to extract the water-soluble
amino acids from the lipid-based content of the ngerprint,
which is composed of triglycerides, wax esters, free fatty acids,
and squalene.
The aqueous phase containing the amino acids
was removed from the ngerprint surface and subsequently
analyzed by the proposed biocatalytic assay. The extraction
process consisted of the following steps: the ngerprints were
deposited onto a portable surface composed of polyethylene
and 120 μL of 0.01 M HCl was placed directly onto the
ngerprint, covering an area of 63 mm2. The entire surface was
Scheme 1. Dual-Enzyme Cascade Assay Containing L-AAO
and HRP Used for the Dierentiation of Gender via
Fingerprint Content
The abbreviations used are L-AAO (L-amino acid oxidase) and HRP
(horseradish peroxidase).
Analytical Chemistry Article
DOI: 10.1021/acs.analchem.5b03323
then heated at 40 °C for 20 min. This process causes the amino
acid content in the ngerprint to migrate from the lipid-based
content into the aqueous acidic solution, while the lipid-based
content remains on the portable lipophilic surface. The aqueous
acidic solution was then collected oof the portable surface
and used as the sample for analysis.
Gender Determination via Bioassay. Here, we are
proposing a bioanity-based sensing system that has the
capability to distinguish between ngerprint samples from
males and females using the concentrations of amino acids
present in ngerprint content. The logic for this determination
is based on the proven fact that females have dierent
concentrations of amino acids in their systems than
The L-AAO enzyme has the ability to use a
large range of L-amino acids as substrates, with a varying degree
of anity,
which drives the enzyme to convert oxygen to
peroxide. L-AAO has previously been used as an amperometric
for the identication of amino acids as well as in an
assay for detecting intestinal peptide hydrolase activity.
peroxide then acts as a substrate for the secondary element of
the cascade, HRP, which oxidizes a dye acting as a cosubstrate,
thus, producing a signal at a particular wavelength. The dye
used in this case was o-dianisidine, which becomes oxidized by
HRP and is consequently detected at 436 nm.
As shown
below, this method, combined with the newly developed
extraction protocol allowing for the isolation of water-soluble
amino acids from the lipid-based ngerprint content, requires
only a minuscule amount of substrate. More importantly, it
provides a quick male/female response and can be performed
on-site. These results can narrow down the possibilities in a
suspect pool in a quick and timely manner when there is no
matching ngerprint image or DNA prole in the correspond-
ing databases. Furthermore, this type of analysis can potentially
be utilized by any and all members of law enforcement with no
need for specialized training, as it works in a similar manner to
pregnancy strips or glucometers.
Statistical Analysis of Mimicked Samples. The dis-
tribution of amino acid concentrations in human ngerprint
content was previously studied,
and a list of the
corresponding average amino acid concentrations can be
found in Table 1. In order to investigate the distribution of
and variability in amino acid concentrations found in
ngerprint content, the inuence of gender was examined.
The studies, referenced above, reported signicant dierences
in the concentrations of certain amino acids when comparing
genders. The reported data were used in the present study to
prepare solutions mimicking the levels of all amino acids
present in the ngerprints of dierent genders.
The rst step of our study began with the statistical analysis
of the available data from previous studies. The values were not
normally distributed, but rather positively skewed and
consistent with a log-normal distribution. The parameters of
the log-normal distribution were available only for overall
amino acid concentrations, while the distribution parameters
estimated from the male and female data came from
logarithmic untransformed data. The available parameters for
a normal distribution were rst corrected for a log-normal
distribution. For each of the 23 amino acids present in the
ngerprint content, random values according to the recalcu-
lated parameters of the log-normal distribution in males and
females were generated using R-project software.
Thus, two
sets of concentration values (25 for males and 25 for females)
of all 23 amino acids were produced and randomly grouped
together. This allowed for the concentration groups to capture
a range of concentrations that amino acids can take in males
and females. Then 25 experiments using these concentration
groups were performed for each gender.
After obtaining the optical responses for the model solutions,
seen in Figure 1, the measured output signal was dened as the
absorbance of the oxidized dye as a function of time, once the
reaction was initiated. The optical responses were then used for
further statistical analysis. The bottom part of the graph
corresponds to the male samples (lower concentrations of the
amino acids) while the top part of the graph agrees with female
samples (higher concentrations of the amino acids). The
Table 1. Average Amino Acid Concentration (mM) Values
for Males and Females Derived from Sweat
AA female conc. (mM) male conc. (mM)
Thr 0.2090 0.1121
Ser 0.9840 0.5208
Glu 0.1780 0.1109
Gly 0.6463 0.3418
Ala 0.3870 0.1968
Cit 0.1967 0.1267
Asp 0.1196 0.0638
Asn 0.0380 0.0161
Gln 0.0178 0.0120
Pro 0.0728 0.0349
Val 0.0919 0.0459
Cys 0.0012 0.0009
Met 0.0085 0.0034
Iso 0.0494 0.0229
Leu 0.0625 0.0324
Tyr 0.0559 0.0303
Phe 0.0378 0.0172
β-ala 0.0128 0.0034
Orn 0.1361 0.0684
Lys 0.0528 0.0285
Trp 0.0151 0.0071
His 0.1790 0.0804
Arg 0.0948 0.0540
These values have been previously reported and were used to prepare
mimicked ngerprint samples.
Figure 1. Change in signal response (λ= 436 nm) corresponding to
the oxidation of o-dianisidine upon reaction of the analytical system.
The top red traces indicate the female samples, and the bottom blue
traces indicate the male samples.
Analytical Chemistry Article
DOI: 10.1021/acs.analchem.5b03323
produced responses, which relate the absorbance to the
concentrations of all 23 amino acids, are clearly dierent
between males and females, with a small overlap between them.
The readout time was initially set to 420 s; however, after
repeating the statistical analysis using later readout times up to
1800 s, the nal result remained almost unchanged. The amino
acid concentrations were chosen to follow the published
distributions that are relevant for males and females; thus, real
applications should generate signals that correspond to the
signal distribution of the mimicked samples.
The area under the ROC curve,
also known as AUC, was
estimated by the trapezoidal integration method, and the
corresponding 95% condence interval (CI) was estimated
using the method described by DeLong et al.
The AUC was
estimated at 0.99 (95% CI, 0.981.00) from the ROC curve,
Figure 2, which means that the L-AAO/HRP assay has a 99%
probability of correctly dierentiating between male and female
ngerprints. The ROC curve was generated from absorbance
changes, and the best absorbance threshold of 0.439, which
balanced the trade-othat exists between sensitivity and
specicity, was determined. The absorbance change is the most
accurate cutopoint for discrimination between male and
female ngerprint samples. As shown, ROC analysis has proven
the potential of this assay to correctly dierentiate between
samples from males and females.
Evaluation of Authentic Fingerprint Samples. The
success in distinguishing between genders utilizing the bioassay
explained above on the mimicked samples led to further studies
involving authentic latent ngerprints. These ngerprints were
collected from two groups of volunteers, Caucasian males and
Caucasian females. The ngerprints were collected on poly-
ethylene lm according to an established procedure described
by Croxton et al.
Once the ngerprints were deposited, the
extraction protocol, detailed in the Experimental Section, was
applied. Following the extraction, the amino acid samples were
subjected to the same bioassay as the mimicked samples. As
anticipated, the aqueous solution removed from the ngerprints
contained the amino acids necessary for analysis, while the
nonpolar content remained on the polyethylene lm. The
success of the extraction of amino acids as well as the bioassays
performance is demonstrated in Figure 3. As seen here, the
samples from the authentic ngerprints generated a noticeably
lower optical signal than that of the mimicked samples (Figure
1), which is a result of the dilution that occurs during the
extraction of the amino acids from the authentic ngerprints.
However, despite the dierence in signal intensity, there is still
a signicant dierence between the samples obtained from
males and the samples obtained from females. The results of
the L-AAO/HRP assay using authentic ngerprints were
consistent with the results of the L-AAO/HRP assay using
mimicked samples in that the female samples generated a
signicantly higher optical signal than that of the male samples,
corresponding to the higher amino acid content. Additionally,
the relative standard deviation between the signals produced by
the authentic ngerprint samples, both left and right thumbs,
does not exceed 8%.
Evaluation of Various Extraction Surfaces. Following
the identication of gender from the authentic ngerprint
samples, the extraction protocol and biocatalytic assay were
further tested on various surfaces that could be found at a crime
scene. Given that authentic male ngerprints did not generate a
signicant signal, only female ngerprints were used for this
experiment. Three female ngerprints were deposited onto
multiple surfaces including a door knob, a laminate desktop, a
composite benchtop, and a computer screen. The polyethylene
lm used in the previous experiment for the determination of
gender was used to remove the ngerprints from the respective
surfaces. The samples were then subjected to the same
extraction protocol, described above, as well as the L-AAO/
Figure 2. Trade-obetween sensitivity and specicity is shown by
presenting data as a receiver operating characteristic (ROC) curve.
Area under the ROC curve (AUC) is 99%, which is the probability for
the presented assay to correctly distinguish between males and females
based on the amino acidsconcentrations in the respective ngerprint
samples. The optimum cutopoint was chosen with a sensitivity and
specicity of 96%. Random choice is denoted by the gray diagonal line.
Figure 3. Data obtained from authentic ngerprint samples from Caucasian males and females: (a) the left thumb and (b) the right thumb.
Analytical Chemistry Article
DOI: 10.1021/acs.analchem.5b03323
HRP bioassay. Figure 4 demonstrates that the extraction
protocol and the bioassay are capable of identifying a female
ngerprint, regardless of the surface from which it was taken.
The L-AAO/HRP bioassay described above for the purpose of
distinguishing between ngerprint samples obtained from both
males and females has proven to be reliable and reproducible.
The ROC analysis conducted using 50 mimicked ngerprint
samples generated statistics proving that it is possible to
determine the gender of the ngerprint originator using this
method. Initial experiments using mimicked ngerprint
methods, concluded that there was a 99% chance of
determining the correct gender of the ngerprint originator.
Furthermore, a reliable sample extraction protocol was
employed for the extraction of the necessary substrates
amino acidsfrom real ngerprint samples collected from
Caucasian male and female volunteers. In the case mentioned
above, the thumbprints of the volunteers were deposited onto a
portable polyethylene lm, where they were subjected to acidic
conditions. The amino were then separated from the lipid-
based components through heating the polyethylene lm. The
results from the analysis of authentic ngerprint samples further
demonstrated the ability of the bioassay to dierentiate
between male and female ngerprint samples based on the
signicant dierence in absorbance intensities. In addition, the
durability of the bioassay and extraction process was
successfully determined using various surfaces from which the
ngerprints were collected.
Corresponding Author
The authors declare no competing nancial interest.
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Analytical Chemistry Article
DOI: 10.1021/acs.analchem.5b03323
... 1 Thus, the number of details and their characteristics that appear after their development individualize the fingerprint and enable the comparison with fingerprint patterns to be carried out, but the number of minutiae is often not enough to carry out a comparison. 3 Since the 1990s, there have been a number of studies to extract other information from fingerprints, such as differentiating adults from children, 4 finding traces of illicit substances and explosives, 5,6 dating 7, 8 and, more recently, the discrimination of male and female subjects. 3,9,10 The understanding of the chemical substances that form fingerprints is essential for these studies, since it is from the understanding of the degradation kinetics, concentration and verification of the existence of a given substance that these new results can be achieved. ...
... 3 Since the 1990s, there have been a number of studies to extract other information from fingerprints, such as differentiating adults from children, 4 finding traces of illicit substances and explosives, 5,6 dating 7, 8 and, more recently, the discrimination of male and female subjects. 3,9,10 The understanding of the chemical substances that form fingerprints is essential for these studies, since it is from the understanding of the degradation kinetics, concentration and verification of the existence of a given substance that these new results can be achieved. The chemical composition of fingerprints originates mainly from the eccrine and sebaceous glands. ...
... The analysis used Raman spectroscopy with partial least square discriminant analysis (PLS-DA) and support vector machine discriminant analysis (SVM-DA), and the results of discrimination were approximately 80-93%. Huynh et al. 3 carried out a biocatalytic method to identify sex using amino acids extracted from the fingerprint using ultraviolet and visible (UV-Vis) spectroscopy. In other studies to determine the sex of human subjects, Widjaja et al. 12 used Raman spectroscopy to analyze nail clippings, and Lednev et al. 13 used Raman spectroscopy to analyze saliva samples. ...
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Latent fingerprint is an important crime scene evidence, but it is not always recoverable or technically suitable for analysis with fingerprint patterns. Forensic science has shown that other information can be explored from traces using chemical compounds. Infrared spectroscopy is a nondestructive technique that is widely applied to a variety of forensic evidence. In this work, infrared spectroscopy and partial least square discriminant analysis were used to determine the human sex based on latent fingermark analysis. Fingerprint samples were taken from 42 male and female donors, then kept in either dark or light storage conditions, and the Fourier transform infrared (FTIR) spectra were measured considering a period of up to 30 days from collection. The regions from 3000 to 2800 cm-1 and 1790 to 1150 cm-1 presented the greatest differences in the peak intensities among the two sex groups. The results showed a correct discrimination rate higher than 80%.
... This means a sufficient amount of minucius to perform comparison with fingerprint templates. If not, it is still possible to use DNA identification techniques to find a person's identity [3]. (Table 1). ...
... Considering the premise that fingerprints can be interpreted as a box carrying some "chemical print", wherein pieces of information like date, sex and use of illegal substances and others can be found, they represent an important sample that can be used to collaborate in a police investigation. Recent studies have suggested that the chemical substances contained in fingerprint composition, like metabolites, can vary as a function of physical properties such as sex, age, ethnicity or health status [3]. Besides, the oil compounds of fingerprints change over time [9]. ...
... In this context, the ability to determine sex from traces like body fluids, nail or fingerprints at the scene of a crime would further advance the infield capabilities of crime scene investigation. Huynh et al. developed a biocatalytic assay for determining sex based on the extraction of amino acids present in the fingerprint using UV-Vis Spectroscopy [3]. Furthermore, a method for sex determination using Raman spectroscopy using fingernail clippings was proposed by Widjaja et al. [10]. ...
From the late 90s until recently, some forensic research has been dedicated to the development of analytical techniques to explore the chemical components present in fingerprints, in order to find other information besides authorship. Raman spectroscopy is a technique of nondestructive analysis of a wide variety of forensic evidence, including fingerprints, at the crime scene. In this context, the aim of this work is to explore Raman spectroscopy and the supervised methods, Partial Least Squares and Support Vector Machine for Discriminant Analysis (PLSDA and SVMDA, respectively), as means to determine sex based on fingerprints obtained from male and female donors and submitted to different conditions (dark and light). Considering a period up to seven days from the collection of the fingerprint, the results showed correct discrimination rates ranging from approximately 80 to 93%.
... Females are known to exhibit higher ridge densities and narrower ridges in their fingerprints than males (Soanboon, Nanakorn, and Kutanan 2016). The amino acid content in latent fingerprints may also be used to differentiate the genders (Huynh et al. 2015). The levels of amino acids in female sweat are approximately twice as high as in males (Huynh et al. 2015). ...
... The amino acid content in latent fingerprints may also be used to differentiate the genders (Huynh et al. 2015). The levels of amino acids in female sweat are approximately twice as high as in males (Huynh et al. 2015). ...
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Fingerprint analysis is widely used in forensic science, primarily for individualization. However, fingerprints are rich with other information pertaining to an individual’s activities; several studies have used matrix-assisted laser desorption/ionization-time of flight (MALDI-ToF) to determine these factors but have been hampered by issues such as the choice of matrix and the time-consuming preparation of samples. Consequently, most analyses are performed using high performance liquid chromatography (HPLC) triple quadrupole instruments which offer high levels of sensitivity and fragment information. These instruments are, however, low resolution which means the mass spectral data can only be expressed to 2 decimal places and require further supporting information such as retention time to ascertain the compounds in the fingerprint. This is especially true if the compounds in question are isobaric. We report a rapid and accurate method of identifying individuals that have been in contact with commonly found cutting agents via latent fingerprint analysis using liquid chromatography electrospray quadrupole time-of-flight mass spectrometry (LC-ESI-qToF-MS). This is the first publication to utilize LC-ESI-qToF-MS instrumentation in both positive and negative modes, obtaining exact mass data used to identify and confirm the presence of cutting agents in latent fingerprints. High resolution mass spectral data have been obtained, which can be reported to 4 decimal places and compared to the theoretical exact mass data of each individual component to within a 5 part per million (ppm) error limit.
... However, fingerprints are easily deposited on suitable surfaces (such as glass or metal or polished stone) by the natural secretions of sweat from the eccrine glands that are present in epidermal ridges (Ashbaugh, 2008). Deliberate impressions of fingerprints may be formed by ink or other substances transferred from the peaks of friction ridges on the skin to a relatively smooth surface such as a fingerprint card (Ahmed and Osman, 2016) Human fingerprints are detailed, nearly unique, difficult to alter, and durable over the life of an individual, making them suitable as long-term markers of human identity (Huynh et al. 2015). Fingerprints of an individual have been used as one of the vital parts of identification in both civil and criminal cases because of their unique properties of absolute identity, they have the patterns constituted by the ridges on the surface of fingers and it is peculiar to each person and remains stable for a lifetime . ...
... In the past, attempts have been made by different researchers (Wang et al. 2007;Ekanem et al. 2009;Soanoboon et al. 2015;Tamil, 2018) to study the distribution of fingerprint patterns in various populations and ethnic divide. Human fingerprints are detailed, unique, difficult to alter, and durable over the lifespan of an individual, making them suitable as long-term bio-markers of human identity (Huynh et al. 2015). Latent fingerprints are primary physical and biological evidence that investigating officers commonly collect in a crime scene and use for personal identification. ...
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The uniqueness of fingerprints makes it a valued biometric trait and since the prints are regularly seen physical evidence in many crime scenes, forensic investigators employ them for sexual and ethnic differentiations when solving criminal cases. This study was an attempt to discriminate sex and ethnicity using thumbprint patterns and ridge density counts between Igbo and Efik tribes of Nigeria. The sample size for this study includes 173 adults (Efik = 37 males, 44 females) and (Igbos = 61 males, 31 females), randomly selected between the ages of 18-40 years. The subjects were asked to wash and dry their hands to remove dirt and grease. The fingers (thumbs) of both hands were smeared with indelible ink and pressed in a white plane paper. Using meter rule, 25mm each was measured from radial border, ulnar border, and inferior quadrants respectively for fingerprint ridge density count. This data was analyzed using SPSS Software version 21 Chicago Incorporated. The results of this study showed that both the males and females of Igbo origin have predominantly loop fingerprint pattern, at the male to female ratio of 43% and 55% respectively. In the contrary, the male and female of Efik ethnic group recorded more whorl print pattern at the ratio of 54% and 50% respectively. More so, this results recorded sexual dimorphism (P<0.05) in the various ridge density count across the two ethnic groups, even the ethnic comparison of both males to males and females to females, recorded statistical significant difference (P<0.05) between the Igbos and Efiks. Hence, the Igbos, irrespective of sex showed more loop fingerprint pattern, contrary to the whorl fingerprint pattern more frequent amongst the Efiks.Thus, the present results will be of immense relevance in forensic practice by unveiling the peculiarities of finger ridge density associated with gender and ethnic origin.
... The extraction of L-AA from ngerprints is performed by using a previous reported thermal/acid leaching protocol with reasonable modi cation. 21 In a typical experiment, 120 μL H 2 SO 4 solution (0.01 M) is directly placed onto the ngerprint on a polyethylene chip. ...
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Fingerprints play vital roles in modern forensic investigations by providing essential personal information. To maximize the efficiency of forensic investigations, highly efficacious protocols are urgently needed for fingerprint capture and information extraction. Herein, a novel L-amino acids (L-AA)-responsive nanoprobe was rationally designed and constructed with orthogonal near-infrared (NIR) and short wave infrared (SWIR) emissions. Due to the difference in L-AA content in fingerprints between males and females, effective gender identification is also practicable by analysing the NIR/SWIR luminescence ratio. More importantly, by utilizing adhesive L-AA on latent fingerprints as a target, simultaneous washing-free NIR/SWIR ratiometric luminescence imaging and forensic gender identification of latent fingerprints are achieved with not only high spatial resolution but advanced precision. Our findings provide a new strategy for the development of a new generation of nanoprobes for simple washing-free fingerprint imaging and valid forensic gender identification.
... Three different types of natural secretion glands in the body and each gland produces a different type of sweat, namely, eccrine, sebaceous, and apocrine. Eccrine sweat glands are found all over the body at 98-99% of water, various inorganic salts (such as chloride, bromide, iodide, fluoride, and phosphate) and organic materials (such as amino acids, fatty acids and urea) surface, eccrine sweat, together with oily substances such as sebum picked up by the finger, forms an impression of the fingers ridge pattern [56] and schematic representation visualization of LFPs shown in Fig. 10 (a) [ 57 , 58 ]. ...
Organic Schiff base compounds with luminous characteristics are receiving attention and increasing demand for the imaging of latent fingerprints (LFPs) at crime scenes. Sb1 and Sb2 novel Schiff base heterocyclic compounds were synthesized and confirmed by using analytical and spectroscopic methods. The existence of both donating and accepting groups influenced the appearance of absorption bands at longer wavelength and was recorded using UV-absorption and emission spectrum in solvent media. Compounds Sb1 and Sb2 emit at 576 nm and 646 nm in bathochromic shift respectively. The electrochemical properties were investigated using cyclic voltammetry. Quantum chemical parameters with vibrational frequency have been estimated in density functional theory (DFT), using TD-DFT/CAM (B3LYP) approach employing 6-311++ G (d, p) basis set in the ground state. Theoretical vibrational frequency values were specifically agreed to obtained experimental values. Furthermore, FMOs, MEPs, RDG analyses and Mulliken atomic charges have been calculated. In addition, LFPs images were developed by powder dusting approach on specified materials using synthetic compounds and visualized under Visible and UV light. The level II and III properties of LFPs on the substrate were observed under light-medium with no background interference, therefore these compounds are potential materials for electroluminescent, OLEDs and forensic science applications.
... Hormonal differences naturally exist between biological males and females, which could influence sebaceous gland activity that is under hormonal regulation [11]. This variation in gland activity between biological sexes could result in compositional differences of the secreted compounds that constitute fingermarks, such as endogenous peptides and proteins [12], amino acids [13][14][15], lipids [16,17], and squalene [18]. Any differences could potentially influence the affinity of a powder developer to the secreted residues and thus the color contrast observed, which is being proposed as a fingermark aging indicator. ...
This research further expands previous studies in which color contrast between ridges and furrows was examined as a possible age indicator for latent fingermarks. Here, the variable biological sex and its influence on aging were investigated. A total of 756 sebaceous‐rich impressions from seven males and seven females were deposited on glass and polystyrene plastic and aged in the dark for three months. At nine discrete times, random fingermarks were visualized with a titanium dioxide–based powder (TiO2), photographed, and edited in Photoshop® to collect pixel color data. Two color contrast‐related metrics, mean color intensity (MI) and intensity amplitude (IA), were analyzed to determine whether the aging processes of biological male and female fingermarks were equivalent. These metrics revealed that impressions from the different biological sexes behaved in a similar manner over time. However, significant effects between substrates were observed. Quadratic regression models best represented the aging trends based on the MI and IA metrics for both male and female fingermarks. The correlation coefficients (R) and coefficients of determination (R2) were moderate to strong for impressions on glass but weaker for plastic. These findings indicated that biological male and female fingermarks could be incorporated into a single universal age estimation model per substrate when utilizing color contrast as an age indicator. Nonetheless, future studies are needed to better understand aging processes on plastic when using this methodology and to determine the life expectancy (i.e., the potential for identification) of latent fingermarks beyond three months.
... During the last decade, other analytical methods based on the chemical differences between sexes have been investigated (Table 9) [16,19,[287][288][289][290][291][292][293]. In all the reported studies, the results showed good performance so further research should be aimed at evaluating the validity of these methods in scenarios that mimic forensic casework. ...
Forensic investigation involves gathering the information necessary to understand the criminal events as well as linking objects or individuals to an item, location or other individual(s) for investigative purposes. For years techniques such as presumptive chemical tests, DNA profiling or fingermark analysis have been of great value to this process. However, these techniques have their limitations, whether it is a lack of confidence in the results obtained due to cross-reactivity, subjectivity and low sensitivity; or because they are dependent on holding reference samples in a pre-existing database. There is currently a need to devise new ways to gather as much information as possible from a single trace, particularly from biological traces commonly encountered in forensic casework. This review outlines the most recent advancements in the forensic analysis of biological fluids, fingermarks and hair. Special emphasis is placed on analytical methods that can expand the information obtained from the trace beyond what is achieved in the usual practices. Special attention is paid to those methods that accurately determine the nature of the sample, as well as how long it has been at the crime scene, along with individualising information regarding the donor source of the trace.
... A dependence of fingerprint features on age group (individuals born at a similar time), gender (physical characteristics that distinguish males from females) and ethnicity (common culture and origin) has been reported [10,16,17]. Methods for demographics estimation from fingerprints have searched for gender clues in the ridge density structure that can be encoded by the local texture [10,18]. ...
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Although the diagnostic ability of a binary classifier system has been effectively assessed using a receiver operating characteristic (ROC) curve, the presence of covariates can affect the discriminatory capacity. This research investigates how automated tools used in forensics introduce demographic biases and discusses performance unfairness mitigation strategies. In our previous work, we evaluated the impact of demographic differentials in automatic matching of latent fingerprints and incorporated these covariates in the ROC curve. The resulting adjusted ROC curve provided error rates that account for an individual’s demographic information, which is a better measure of the discriminatory capacity compared to the pooled ROC curve. Our ROC regression model was also able to handle continuous covariates such as age as well as discrete covariates such as gender and ethnicity. In this paper, we extend the preliminary study carried out on right index latent fingerprints to right thumb instances. We investigate: (i) until which extent demographic differential vary depending on properties specific to the finger instance (e.g., size of the fingertip); (ii) the effectiveness of the proposed demographic adjusted-ROC to handle unfairness.
... The fingerprints are formed during 12-19 weeks of the intra uterine life and they remain the same throughout the life. They have provided strong evidences of personal identification during crime scenes 32 . The uniqueness was confirmed in this study as well, as no similar finger prints between any two individuals were observed. ...
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Aim: To determine the correlation between lip print, fingerprint form and blood groups that can be used for the identification of an individual among gender. Method: This cross-sectional study was conducted among 719 female and male participants with ages between 17-34 years from Bahria University Medical and Dental College. Patterns for lip and finger prints were collected along with the blood groups. SPSS v23 was used for statistical analysis. Frequency and percentages of the qualitative variables was calculated. The association of the variables was analyzed using Chi-square. Results: A total of 719 subjects, there were 327 males (45.5%) and 392 females (54.5%). Type I lip pattern was prevalent in 31.8% males followed by Type I’ in 27.6% females. The loop type of the finger print was observed in 165(50.5%) of males and 162(41.3%) females. The most common type of blood group was A+ in 27.2% in males while in females it was O+ in 29.8%. Conclusion: Individual parameters such as lip and finger prints along with blood groups can play an important role in personal identification of individual. In our study A+ blood group along with arch pattern of finger prints and Type I lip were most common patterns in males while in females Type I’lip pattern along with blood group 0+ and Loop pattern were common Keywords: Lip prints, Finger Prints, Cheiloscopy, Blood Groups, Forensic
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A bioaffinity-driven cascade assay was developed to determine the time elapsed from the point a blood sample was left at a crime scene to the point of discovery. Two blood markers, creatine kinase (CK) and alanine transaminase (ALT), were utilized to determine the age of the blood spot based on their natural denaturation processes. The analysis with the proposed bioassay was performed in human serum samples, which underwent the aging process under environmental conditions that could be expected at crime scenes. The concentration of the markers in the sample was based on physiological levels present in healthy adults. These two markers were concerted in a biocatalytic cascade composed of two parallel subsystems, with each of them following the activity of one marker. Both markers have very distinct denaturation rates which would not allow them to be used in a single marker setup while still providing satisfactory results. However, by parallel tunable monitoring of both markers, it is possible to provide information of the blood sample age with low temporal error for a prolonged period of time. To mimic a possible real crime scene situation - the reliability of the proposed assay was then successfully tested on dried/aged serum samples (up to 5 days old) in environments with different temperatures.
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A new biocatalytic assay analyzing the simultaneous presence of creatine kinase (CK) and alanine transaminase (ALT) was developed aiming at the recognition of biofluids of different gender for forensic applications. Knowing the difference in the concentrations of CK and ALT enzymes in the blood of healthy adults of male and female groups we mimicked the samples of different gender with various CK-ALT concentrations. The analysis was performed using a multi-enzyme/multi-step biocatalytic cascade where the differences in both included enzymes resulted in an amplified difference in the final analytical response. The analysis performed in human serum solutions allowed discrimination of samples corresponding to male/female groups. The robustness of the developed analysis allowed determination of the gender for serum solutions after their drying and ageing at least for 1 hour. Importantly for forensic applications, reaction with a chromogenic reactant nitroblue tetrazolium allowed qualitative discrimination of the "male" and "female" samples by the naked eye.
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A new biocatalytic assay analyzing the simultaneous presence of creatine kinase (CK) and lactate dehydrogenase (LDH) was developed aiming at the recognition of biofluids of different ethnic origins for forensic applications. Knowing the difference in the concentrations of CK and LDH in the blood of healthy adults of two ethnical groups, Caucasian (CA) and African American (AA), and taking into account the distribution pattern, we mimicked the samples of different ethnic origins with various CK-LDH concentrations. The analysis was performed using a multi-enzyme/multi-step biocatalytic cascade where the differences in both included enzymes resulted in an amplified difference in the final analytical response. The statistically established analytical results confirmed excellent probability to distinguish samples of different ethnic origins (CA vs. AA). The standard enzymatic assay routinely used in hospitals for the analysis of CK, performed for comparison, was not able to distinguish the difference in samples mimicking blood of different ethnic origins. The robustness of the proposed assay was successfully tested on dried/aged serum samples (up to 24 h) - in order to mimic real forensic situations. The results obtained on the model solutions were confirmed by the analysis of real serum samples collected from human subjects of different ethnic origins.
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After over a century, fingerprints are still one of the most powerful means of biometric identification. The conventional forensic workflow for suspect identification consists of (i) recovering latent marks from crime scenes using the appropriate enhancement technique and (ii) obtaining an image of the mark to compare either against known suspect prints and/or to search in a Fingerprint Database. The suspect is identified through matching the ridge pattern and local characteristics of the ridge pattern (minutiae). However successful, there are a number of scenarios in which this process may fail; they include the recovery of partial, distorted or smudged marks, poor quality of the image resulting from inadequacy of the enhancement technique applied, extensive scarring/abrasion of the fingertips or absence of suspect's fingerprint records in the database. In all of these instances it would be very desirable to have a technology able to provide additional information from a fingermark exploiting its endogenous and exogenous chemical content. This opportunity could potentially provide new investigative leads, especially when the fingermark comparison and match process fails. We have demonstrated that Matrix Assisted Laser Desorption Ionisation Mass Spectrometry and Mass Spectrometry Imaging (MALDI MSI) can provide multiple images of the same fingermark in one analysis simultaneous with additional intelligence. Here, a review on the pioneering use and development of MALDI MSI for the analysis of latent fingermarks is presented along with the latest achievements on the forensic intelligence retrievable.
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The free amino acid (AA) composition of eccrine sweat is different from other biological fluids, for reasons which are not properly understood. We undertook the detailed analysis of the AA composition of freshly isolated pure human eccrine sweat, including some of the key derivatives of AA metabolism, to better understand the key biological mechanisms governing its composition. Eccrine sweat was collected from the axillae of 12 healthy subjects immediately upon formation. Free AA analysis was performed using an automatic AA analyser after ninhydrin derivatization. Pyrrolidine-5-carboxylic acid (PCA) and urocanic acid (UCA) levels were determined using GC/MS. The free AA composition of sweat was dominated by the presence of serine accounting for just over one-fifth of the total free AA composition. Glycine was the next most abundant followed by PCA, alanine, citrulline and threonine, respectively. The data obtained indicate that the AA content of sweat bears a remarkable similarity to the AA composition of the epidermal protein profilaggrin. This protein is the key source of free AAs and their derivatives that form a major part of the natural moisturizing factor (NMF) within the stratum corneum (SC) and plays a major role in maintaining the barrier integrity of human skin. As perturbations in the production of NMF can lead to abnormal barrier function and can arise as a consequence of filaggrin genotype, we propose the quantification of AAs in sweat may serve as a non-invasive diagnostic biomarker for certain atopic skin conditions, that is, atopic dermatitis (AD).
This review describes the various types of sebaceous glands, their locations, and where possible their different functions. All sebaceous glands are similar in structure and secrete sebum by a holocrine process. However, the nature of this secretion and the regulation of the secretory process seem to differ among the various types of glands. Methods for measuring sebum secretion and assessing sebaceous gland activity are also described. The area of major interest during the last 20 years has undoubtedly been the mechanisms that control sebaceous gland function. Most studies have focused on the endocrine control and in particular on the role of androgens and pituitary hormones, although evidence suggests that nonendocrine factors may also be important. However, many questions remain and during the next few years attention will certainly be given to the role of retinoids and their mode of action in the treatment of acne.
Fingerprint identification has been an accepted forensic discipline for more than 110 years. But how far have we come with respect to the interpretation and reporting of fingerprint evidence? Should the discipline follow the DNA lead and introduce mathematical models for the assessment of fingerprint evidence, with the ‘statistic' – the number generated by the model – then becoming the evidence presented in court? Further to this, and with respect to evidence that can be given a statistical value, to what extent are we meeting our professional obligation to ensure that the weight of the evidence we present in court is fully understood and not misinterpreted?
The analysis of amino acids present in fingerprints has been studied several times. In this paper, we report a method for the analysis of amino acids using an fluorenylmethyloxycarbonyl chloride-derivatization for LC separation and MS detection. We have obtained good results with regard to the calibration curves and the limit of detection and LOQ for the target compounds. The extraction of the amino acids from the substrates used proved to be very efficient. Analysis of the derivatized amino acids enabled us to obtain full amino acid profiles for 20 donors. The intervariability is as expected rather large, with serine as the most abundant constituent, and when examining the total profile of the amino acids per donor, a characteristic pattern can be observed. Some amino acids were not detected in some donors, or fell out of the range of the calibration curve, where others showed a surprisingly high amount of material in the deposition analyses. Further investigations will have to address the intravariability of the amino acid profiles of the fingerprints from donors. By the development of the analytical method and the application to the analysis of fingerprints, we were able to gain insight in the variability of the constituents of fingerprints between the donors.
The increased importance of closed-cycle life support systems has produced for accumulating information on by-products of human metabolism. This publication consists of 598 references covering the composition of feces, sweat, and urine. Topics which are discussed include methods of analysis; the constancy at which the formed or waste products are created; and the relative influence exerted thereon by diet, climate, body activity, and stress. Most of the references were published between January 1957 and June 1962. A subject index is included.
Despite advances in DNA, fingermarks remain one the best forms of evidence available. While fingermarks are routinely analyzed in terms of their patterns, it may be possible to obtain additional information in terms of their chemical composition. If successful, a chemical analysis of the constituents of a fingermark may give scientists additional information that may help in the identification of a person. The results presented herein describe the initial investigation into the analytical determination of some of these compounds, specifically the fatty acids. This study was specifically aimed at identifying possible fatty acids, which could aid in profiling or perhaps uniquely identifying an individual. Preliminary data obtained in this study suggests that this may in fact be possible, though additional research is certainly necessary. Utilizing gas chromatography-mass spectrometry, significant differences in the ratios of several fatty acid methyl esters were found when comparing individuals of varying race and gender. In addition, large intervariability and intravariability was discovered for some compounds, suggesting the possibility of being able to individualize based on chemical profile. Follow-up investigations will continue to determine whether this continues to be the case as greater numbers of individuals are sampled and more extensive control and information on the subjects is obtained.