Body Fluid Stains Research Articles

Near-infrared excitation Raman spectroscopy of colored fabric contaminated with body fluids

Confirmatory identification of dyes in the physical pieces of evidence, such as hair and fabric, is critically important in forensics. This information can be used to demonstrate the link between a person of interest and a crime scene. High performance liquid chromatography is broadly used for dye analysis. However, this technique is destructive and laborious. This problem can be overcome by near-Infrared excitation Raman spectroscopy (NIeRS), non-invasive and non-destructive technique that can be used to determine chemical structure of highly fluorescent dyes. Analyzed fabric materials often possess body fluid stains, which may obscure the accuracy of NIeRS-based identification of dyes. In this study, we investigate the extent to which fabric contamination with body fluids can alter the accuracy of NIeRS. Our results showed that NIeRS coupled with partial-least squared discriminant analysis (PLS-DA) enabled on average 97.6% accurate identification of dyes on fabric contaminated with dry blood, urine and semen. We also found that NIeRS could be used to identify blood, urine and semen on such fabric with 99.4% accuracy. Furthermore, NIeRS could be used to differentiate between wet and dry blood, as well as reveal the presence of blood on washed fabric. These results indicate that NIeRS coupled with PLS-DA could be used as a robust and reliable analytical approach in forensic analysis of fabric.

Body fluids should be identified before estimating the time since deposition (TsD) in microbiome-based stain analyses for forensics.

Identification and the time since deposition (TsD) estimation of body fluid stains from a crime scene could provide valuable information for solving the cases and are always difficult for forensics. Microbial characteristics were considered as a promising biomarker to address the issues. However, changes in the microbiota may damage the specific characteristics of body fluids. Correspondingly, incorrect body fluid identification may result in inaccurate TsD estimation. The mutual influence is not well understood and limited the codetection. In the current study, saliva, semen, vaginal secretion, and menstrual blood samples were exposed to indoor conditions and collected at eight time points (from fresh to 30 days). High-throughput sequencing based on the 16S rRNA gene was performed to characterize the microbial communities. The results showed that a longer TsD could decrease the discrimination of different body fluid stains. However, the accuracies of identification still reached a quite high value even without knowing the TsD. Correspondingly, the mean absolute error (MAE) of TsD estimation significantly increased without distinguishing the types of body fluids. The predictive TsD of menstrual blood reached a quite low MAE (1.54 ± 0.39 d). In comparison, those of saliva (6.57 ± 1.17 d), semen (6.48 ± 1.33 d), and vaginal secretion (5.35 ± 1.11 d) needed to be further improved. The great effect of individual differences on these stains limited the TsD estimation accuracy. Overall, microbial characteristics allow for codetection of body fluid identification and TsD estimation, and body fluids should be identified before estimating TsD in microbiome-based stain analyses.IMPORTANCEEmerged evidences suggest microbial characteristics could be considered a promising tool for identification and time since deposition (TsD) estimation of body fluid stains. However, the two issues should be studied together due to a potential mutual influence. The current study provides the first evidence to understand the mutual influence and determines an optimal process for codetection of identification and TsD estimation for unknown stains for forensics. In addition, we involved aged stains into our study for identification of body fluid stains, rather than only using fresh stains like previous studies. This increased the predictive accuracy. We have preliminary verified that individual differences in microbiotas limited the predictive accuracy of TsD estimation for saliva, semen, and vaginal secretion. Microbial characteristics could provide an accurate TsD estimation for menstrual blood. Our study benefits the comprehensive understanding of microbiome-based stain analyses as an essential addition to previous studies.

An mRNA profiling assay incorporating coding region InDels for body fluid identification and the inference of the donor in mixed samples

Biological traces discovered at crime scenes hold significant significance in forensic investigations. In cases involving mixed body fluid stains, the evidentiary value of DNA profiles depends on the type of body fluid from which the DNA was obtained. Recently, coding region polymorphism analysis has proved to be a promising method for directly linking specific body fluids to their respective DNA contributors in mixtures, which may help to avoid "association fallacy" between separate DNA and RNA evidence. In this study, we present an update on previously reported coding region Single Nucleotide Polymorphisms (cSNPs) by exploring the potential application of coding region Insertion/Deletion polymorphisms (cInDels). Nine promising cInDels, selected from 70 mRNA markers based on stringent screening criteria, were integrated into an existing mRNA profiling assay. Subsequently, the body fluid specificity of our cInDel assay and the genotyping consistency between complementary DNA (cDNA) and genomic DNA (gDNA) were examined. Our study demonstrates that cInDels can function as important multifunctional genetic markers, as they provide not only the ability to confirm the presence of forensically relevant body fluids, but also the ability to associate/dissociate specific body fluids with particular donors.

Construction of an Analysis Model of mRNA Markers in Menstrual Blood Based on Naïve Bayes and Multivariate Logistic Regression Methods.

To establish the menstrual blood identification model based on Naïve Bayes and multivariate logistic regression methods by using specific mRNA markers in menstrual blood detection technology combined with statistical methods, and to quantitatively distinguish menstrual blood from other body fluids. Body fluids including 86 menstrual blood, 48 peripheral blood, 48 vaginal secretions, 24 semen and 24 saliva samples were collected. RNA of the samples was extracted and cDNA was obtained by reverse transcription. Five menstrual blood-specific markers including members of the matrix metalloproteinase (MMP) family MMP3, MMP7, MMP11, progestogens associated endometrial protein (PAEP) and stanniocalcin-1 (STC1) were amplified and analyzed by electrophoresis. The results were analyzed by Naïve Bayes and multivariate logistic regression. The accuracy of the classification model constructed was 88.37% by Naïve Bayes and 91.86% by multivariate logistic regression. In non-menstrual blood samples, the distinguishing accuracy of peripheral blood, saliva and semen was generally higher than 90%, while the distinguishing accuracy of vaginal secretions was lower, which were 16.67% and 33.33%, respectively. The mRNA detection technology combined with statistical methods can be used to establish a classification and discrimination model for menstrual blood, which can distignuish the menstrual blood and other body fluids, and quantitative description of analysis results, which has a certain application value in body fluid stain identification.

Identification of Human Body Fluid Stains and Non-Biological Stains by Three-Dimensional Fluorescence Spectroscopy.

To establish a rapid and nondestructive identification method for human body fluid stains and non-biological stains using three-dimensional fluorescence spectroscopy. The collected three-dimensional fluorescence spectrum data of human saliva, 3% blood, coffee and Fanta® stains were processed with dimensionality reduction. After wavelet transform, spectral denoising and feature extraction, the classification formula was established. The Fisher discriminant was used for spectrum matching and recognition to establish the analysis method to distinguish stain types. According to the results of data training and comparison, all the recognition accuracies of Fanta®, coffee, saliva and blood were more than 91.39%. Among them, saliva reached 100% recognition accuracy. Three-dimensional fluorescence spectroscopy is a potential method for rapid and nondestructive identification of biological and non-biological stains.

Establishment of a co-analysis system for personal identification and body fluid identification: a preliminary report.

Analysis of genetic markers can provide clues for case investigation. Short tandem repeat (STR) detection and analysis are widely used for both personal identification and parentage testing. However, DNA analysis currently cannot provide sufficient information for body fluid identification. Tissue or cell sources of samples can be identified by detecting body fluid-specific mRNA markers, which have been studied thoroughly. Integrating STR profiling and mRNA expression patterns can provide more information than conventional methods for investigations and the reconstruction of crime scenes; this can be achieved by DNA/RNA co-extraction technology, which is economical, efficient, and suitable for low-template samples. Here, we propose a co-analysis system based on the PowerPlex 16 kit. This system can simultaneously amplify 25 markers, including 15 STRs, one non-STR amelogenin, and nine mRNA markers (three blood-specific, two saliva-specific, two semen-specific, and two housekeeping gene markers). The specificity and sensitivity of the co-analysis system were determined and aged and degraded samples were used to validate the stability of the co-analysis system. Finally, different DNA/RNA ratios and various carriers were evaluated. The results showed that the DNA/RNA co-analysis system correctly identified different types of body fluid stains. The STR profiles obtained using the co-analysis system were identical to those obtained using the PP16 kit, which demonstrates that the mRNA primers used did not affect STR profiling. Complete STR and mRNA profiles could be obtained from 1/8 portions of buccal swabs, 1/16 portions of swabs of blood and semen samples, 0.1 cm2 of blood samples, 0.25 cm2 of semen samples, and 1.0 cm2 saliva samples. Additionally, our findings indicate that complete STR and mRNA profiles can be obtained with this system from blood and semen samples when the DNA/RNA ratio is 1:1/32. This study suggests that the co-analysis system could be used for simultaneous personal identification and body fluid identification.

Precise and comprehensive determination of multiple body fluids by applying statistical cutoff values to a multiplex reverse transcription-PCR and capillary electrophoresis procedure for forensic purposes

Body fluid identification from crime scene evidence is an essential procedure in forensic investigations. Among various procedures, multiplex reverse transcription PCR assays have a clear advantage over conventional methods because different types of body fluids can be analyzed simultaneously. For more precise, comprehensive, and objective identification of forensically relevant body fluids, 15 target genes for blood, saliva, semen, vaginal fluid, and nasal secretion were selected; their primers were re-designed and multiplex PCR conditions were optimized to prioritize specificity for those body fluids. Multiple amplicons were separated and determined by the SeqStudio Genetic Analyzer with an all-in-one and easy-to-use cartridge. Then, the cutoff value was set for each marker to eliminate the detection of slight amplification in non-targeted body fluids. As a result, the targeted body fluid specificities of the developed procedure were drastically improved. Although successful determination of the target gene depends on sample condition and marker sensitivity, our procedure was applicable for the precise determination of body fluids in mixed body fluid stains, aged samples, and various mock casework samples. Therefore, it could be a powerful and convenient tool for the precise identification of multiple body fluids in forensic laboratories.

Evaluating the use of hypoxia sensitive markers for body fluid stain age prediction

To augment DNA profiling and body fluid identification techniques efforts are being made to increase the amount of information available from a crime scene stain, which includes efforts to identify externally visible characteristics through phenotypic analysis. A key question surrounding crime scene stains is the length of time between deposition of the stain and its subsequent recovery, in that is the stain recovered related to the incident in question or from a previously deposited stain number of weeks earlier? The inability to answer this fundamental question has a detrimental effect upon the successful completion of a criminal investigation. Once a body fluid leaves the body, the oxygen concentration in the environment changes; therefore, it may be that this change could cause a change in the expression of hypoxia-sensitive biomarkers. Here, a range of bloodstains, liquid saliva and liquid semen samples were collected at 0 days, 7 days, 14 days, 21 days and 28 days of degrading at room temperature (19–22 °C), before undergoing total RNA extraction and cDNA synthesis. Blood was recovered from filter paper with 3 mm2, with saliva and semen being left in their tubes and swabbed at the appropriate times. All samples then underwent quantitative PCR targeting Vascular Endothelial Growth Factor A (VEGFA) and Hypoxia-Inducible Factor 1 Alpha (HIF1A), with B-Actin (ACTB) as a reference gene. A range of linear and quadratic correlation values was obtained from the qPCR data and used to develop a predictive model with a mean absolute deviation (MAD) of 4.2, 2.1, and 5 days for blood, saliva, and semen respectively. Blind testing indicated that a stain age prediction model based upon VEGFA with ACTB as a reference gene could be used on samples up to four weeks old with a margin of error ranging from 2 days through to 5 days. While a sizeable potential time frame exists using this model; this represents a significant step towards the target of having an accurate stain age prediction model.

Detection of vaginal fluid stains on common substrates via ATR FT-IR spectroscopy.

The analysis of body fluids is of utmost importance in forensic casework since many biological fluids contain DNA. The ATR FT-IR spectroscopy is an emerging approach for the confirmatory, rapid, facile, non-destructive, and on-site identification and differentiation of body fluid stains. Notwithstanding the ATR FT-IR spectroscopy is showing a colossal promise towards the identification of body fluids, and further forensic enquiry related to substrate's interference is still in its infancy stage. Therefore, in the present proof-of-concept study, the ATR FT-IR spectroscopy has been utilized for the detection of vaginal fluid stains and to investigate the effect of different substrates on sample analysis. Simulated vaginal fluid samples were prepared on some selected substrates such as glass, plastic, floor tiles, polished wood, paper, and on various cloth substrates and analyzed without any prior sample preparation. Results suggested that vaginal fluid can be successfully detected on non-porous substrates, but it turned out to be a challenging task on porous substrates. However, on the basis of certain peaks, successful identification of vaginal fluid can be done directly on various case-related substrates. The best approach for the detection of vaginal fluid depends upon the nature of substrates and type of interference encountered. In addition, 10 non-vaginal fluid substances which look similar to vaginal fluid and which may lead to misclassification of vaginal fluid or can deliver false-positive results were also analyzed. The spectra of look-alike substances were classified using the chemometric tools such as PCA and PCA-LDA. The developed PCA model successfully classified all vaginal fluid samples from non-vaginal fluid substances with 100% accuracy, specificity, and sensitivity rate. In addition, the effects of other factors such as aging and mixing with other body fluids have also been studied and the results have been described.

A universal test for the forensic identification of all main body fluids including urine

A critical aspect of forensic investigation is to detect and identify body fluid stains and preserve them for DNA extraction. The types of body fluid stains commonly found at a crime scene include blood, saliva, semen, sweat, vaginal fluid, and urine. Identification of a stain can be difficult as current methods are body fluid specific and mostly destructive. In an effort to develop a universal, confirmatory and nondestructive approach which can identify and differentiate body fluids Muro et al. (2016), combined Raman spectroscopy and chemometrics to build a statistical model which could differentiate peripheral blood, saliva, semen, sweat, and vaginal fluid. However, this model did not include urine. Urine can be vital evidence in cases of correctional officers being assaulted with urine bombs by prisoners, as well as in sexual assault cases. Recent studies have also shown that DNA can be extracted from a dried urine sample. In this study, we have combined the Raman spectral dataset collected by Muro et al. with Raman spectral data collected from 27 urine samples from different donors to build calibration and validation datasets. Chemometrics was applied to build an enhanced statistical model which can identify and differentiate all main body fluids including peripheral blood, saliva, semen, sweat, vaginal fluid, and urine. This classification model offers a universal, single step, non-destructive, and robust technique with 100% accuracy for sample identification.

Assigning forensic body fluids to donors in mixed body fluids by targeted RNA/DNA deep sequencing of coding region SNPs.

Biological traces found at crime scenes are analysed not only to genetically identify the donor(s) but also to determine the composition of the stain. For some cases, it is essential to associate a body fluid with a donor. Especially in mixed body fluid stains, but also in body fluid stains that appear to be single-source, this may be of importance. Linking a DNA profile (sub-source level) with evidence from a presumptive test or mRNA analysis (source level) is not straightforward. Our results support that associating donors and body fluids by means of comparing mixture ratios in RNA and DNA is not recommended. We introduce a set of 35 coding region SNPs (cSNPs) in body fluid-specific mRNA transcripts that represent a direct link between the body fluids and their donors. The discrimination power of the cSNPs was estimated based on allele frequencies calculated from a population sample (n = 188), and we investigated the practical application of the cSNPs in different scenarios. The results demonstrate that more cSNPs are needed to improve the discrimination power. However, the findings are promising as we were able to associate donors with body fluids in mixtures of different body fluids as well as in stains where both donors have contributed the same body fluid, e.g. a blood-blood mixture. In addition, the cSNP assay can be used for body fluid identification. The results of this proof-of-concept study support the use of cSNPs to assign body fluids to the respective donors.

Body fluid identification and assignment to donors using a targeted mRNA massively parallel sequencing approach – results of a second EUROFORGEN / EDNAP collaborative exercise

In a previous EUROFORGEN/EDNAP collaborative exercise, we tested two assays for targeted mRNA massively parallel sequencing for the identification of body fluids/tissues, optimized for the Illumina MiSeq/FGx and the Ion Torrent PGM/S5 platforms, respectively. The task of the second EUROFORGEN/EDNAP collaborative exercise was to analyze dried body fluid stains with two different multiplexes, the former Illumina 33plex mRNA panel for body fluid/tissue identification and a 35plex cSNP panel for assignment of body fluids/tissues to donors that was introduced in a proof-of-concept study recently. The coding region SNPs (cSNPs) are located within the body fluid specific mRNA transcripts and represent a direct link between the body fluid and the donor.We predicted the origin of the stains using a partial least squares discriminant analysis (PLS-DA) model, where most of the single source samples were correctly predicted. The mixed body fluid stains showed poorer results, however, at least one component was predicted correctly in most stains. The cSNP data demonstrated that coding region SNPs can give valuable information on linking body fluids/tissues with donors in mixed body fluid stains. However, due to the unfavorable performance of some cSNPs, the interpretation remains challenging. As a consequence, additional markers are needed to increase the discrimination power in each body fluid/tissue category.

Evaluating the use of hypoxia sensitive markers for body fluid stain age prediction

In order to augment DNA profiling and body fluid identification techniques, efforts are being made to increase the amount of information available from a crime scene stain, which includes efforts to identify externally visible characteristics through phenotypic analysis. A key question surrounding crime scene stains is the length of time between deposition of the stain and its subsequent recovery, in that is the stain recovered related to the incident in question or from a previously deposited stain number of weeks earlier? The inability to answer this fundamental question has a detrimental effect upon the successful completion of a criminal investigation. Once a body fluid leaves the body, the oxygen concentration in the environment changes, therefore it may be that this change could cause a change in expression of hypoxia-sensitive biomarkers. Here, a range of blood, saliva and semen samples were collected at 0 days, 7 days, 14 days, 21 days and 28 days of degrading at room temperature, before undergoing total RNA extraction and cDNA synthesis. All samples then underwent quantitative PCR targeting Vascular Endothelial Growth Factor A (VEGFA) and Hypoxia-Inducible Factor 1 Alpha (HIF1A), with B-Actin (ACTB) as a reference gene. A range of linear and quadratic correlation values was obtained from the qPCR data and used to develop a predictive model with a mean absolute deviation (MAD) of 5.3, 2.0, and 4.3 days for blood, saliva, and semen respectively. Blind testing indicated that a stain age prediction model based upon VEGFA with ACTB as a reference gene could be used on stains up four weeks old with a margin of error ranging from 2 days through to 5 days. Whilst a large potential time frame exists using this model, this represents a major step towards the target of having an accurate stain age prediction model.

Detection of fly artifacts from four species of necrophagous flies on household materials using immunoassays.

An immunoassay was previously developed as a technique to improve methods for detection and analysis of fly artifacts found at crime scenes. The dot blot assay utilized a polyclonal antiserum (anti-md3) based on a unique digestive cathepsin D found in cyclorrhaphous Diptera. In this study, artifacts produced by adults of Calliphora vicina, Cynomya cadaverina, Sarcophaga bullata, and Protophormia terraenovae were examined using the immunoassay to determine if insect-derived stains could be distinguished from a range of human body fluid stains. A lift technique was developed which permitted transfer of fly artifacts from test materials to filter paper for dot blot analyses. All species readily deposited artifacts on all test household materials regardless of diet consumed. Despite differences in texture and porosity of the household materials, artifacts of all species transferred to the filter paper. With all fly species, anti-md3 serum bound to artifacts produced after feeding on semen, blood, feces, urine, and saliva. By contrast, anti-md3 serum did not react with any of the human fluids tested, nor with any of the lifts from household materials not exposed to flies. There was no evidence of false positives with any of the fly species tested, regardless of diet consumed. There was also no indication of false negatives with any of the dot blot assays. These observations suggest that immunoassays using anti-md3 serum performed on a simple lift of suspected fly artifacts can be used effectively as a confirmatory assay to distinguish fly regurgitate and fecal stains from human body fluids.

Raman spectroscopy for forensic bloodstain identification: Method validation vs. environmental interferences

The identification of body fluid (BF) stains at a crime scene is an important step of a crime scene investigation since traces of BFs are typically the main source of DNA evidence. Raman spectroscopy is a new emerging method for identifying and differentiating between BF stains. As any new analytical method developed for identification and differentiation of classes of materials, it needs to be evaluated for potential environmental interferences (EIs). This study specifically focused on proving that Raman spectroscopy is not susceptible to false positive (FP) assignments from EIs specific to blood. Twenty-four EI substances that may be misclassified as blood due to either their appearance, or known to provide a FP result with forensic crime scene tests for blood identification were analyzed in this study. The spectra of the twenty-four substances were tested against a recently developed support vector machines discriminant analysis (SVMDA) classification model used for BF differentiation. The SVMDA model identified all substances as not peripheral blood, but some of the substances were predicted as one of the other four BFs. Therefore, random forests (RF) analysis was employed to build a new, more robust, classification method to overcome this limitation. Using this approach, complete separation was achieved based on a classification probability threshold of 70%. This method can also be used in the future to test potential EI substances specific to other common BFs.

Estimating time since deposition using quantification of RNA degradation in body fluid-specific markers

The first appearance of ribonucleic acid (RNA) in forensic science research was in 1984 in the study of post-mortem tissues. Since then, many studies have explored the role of gene expression and its potential applications in forensic science. The two main RNA molecules that have been subject to increasing interest in the forensic science community are messenger RNA (mRNA) and microRNA (miRNA). Identification of body fluid type and estimating the time since deposition can be of immense value to criminal investigations. Determining the time since deposition or age of a biological stain can help to indicate either when a crime happened, or whether the biological evidence was deposited before/after a known crime event, in order for samples to be excluded. The research presented here has used reverse transcription quantitative PCR to examine the relative expression ratio (RER) in two types of body fluid-specific markers (saliva and semen), to develop a method to estimate the age of biological stains. mRNA and miRNA markers specific to saliva and semen, along with three reference genes were selected. Biological samples from 20 participants were stored in a dark dry place at room temperature to simulate natural ageing. A series of desired ageing points were set and total RNA was extracted when samples reached each desired point. The degradation behaviour of each RNA marker was analysed, showing that they exhibited unique degradation profiles across a one-year storage interval for saliva and semen samples, where miRNAs and the U6 reference gene were shown to have high stability. The RERs exhibit a non-linear relationship with body fluid stain age and can be considered as a potential method for body fluid stain age estimation, hence the time since deposition.

A Simple Method for Testing Spider Mite Susceptibility to Acaricides Using Body Fluid Stains in an Envelope

A Simple Method for Testing Spider Mite Susceptibility to Acaricides Using Body Fluid Stains in an Envelope

The evaluation and validation of Phadebas® paper as a presumptive screening tool for saliva on forensic exhibits

The Phadebas® Forensic Press Test is routinely used for the detection of saliva. However, assessment of the use of Phadebas® paper for this purpose has not been studied extensively. The suitability of Phadebas® paper as a presumptive screening tool for saliva on forensic exhibits, was investigated by analysing the following: (1) sensitivity, (2) specificity, (3) effects of temperature on sensitivity and specificity, (4) detection of saliva in mixed body fluid samples, and (5) influence of substrate porosity. The results of this study demonstrated that Phadebas® paper is more sensitive to α-amylase activity and less specific for saliva than previously reported. The use of an examination temperature of 37°C had no effect on sensitivity, but increased the incidence of cross-reactivity with other forensically relevant body fluid stains. Blood, urine and vaginal secretions can inhibit the detection of α-amylase activity with Phadebas® paper in mixed stains of saliva and body fluid. Substrate porosity is a weak predictor for the time taken for a saliva stain to achieve a strong positive result on Phadebas® paper. Overall, this study demonstrated that the Phadebas® Forensic Press Test has limitations as a presumptive test for the accurate identification of saliva.

Body fluid identification using a targeted mRNA massively parallel sequencing approach – results of a EUROFORGEN/EDNAP collaborative exercise

In a previous study we presented an assay for targeted mRNA sequencing for the identification of human body fluids, optimised for the Illumina MiSeq/FGx MPS platform. This assay, together with an additional in-house designed assay for the Ion Torrent PGM/S5 platform, was the basis for a collaborative exercise within 17 EUROFORGEN and EDNAP laboratories, in order to test the efficacy of targeted mRNA sequencing to identify body fluids. The task was to analyse the supplied dried body fluid stains and, optionally, participants’ own bona fide or mock casework samples of human origin, according to specified protocols. The provided primer pools for the Illumina MiSeq/FGx and the Ion Torrent PGM/S5 platforms included 33 and 29 body fluid specific targets, respectively, to identify blood, saliva, semen, vaginal secretion, menstrual blood and skin. The results demonstrated moderate to high count values in the body fluid or tissue of interest with little to no counts in non-target body fluids. There was some inter-laboratory variability in read counts, but overall the results of the laboratories were comparable in that highly expressed markers showed high read counts and less expressed markers showed lower counts. We performed a partial least squares (PLS) analysis on the data, where blood, menstrual blood, saliva and semen markers and samples clustered well. The results of this collaborative mRNA massively parallel sequencing (MPS) exercise support targeted mRNA sequencing as a reliable body fluid identification method that could be added to the repertoire of forensic MPS panels.

An investigation into the use of the ParaDNA® body fluid identification system in forensic examinations

Examinations carried out in forensic laboratories currently utilise chemical screening tests and microscopic analysis to locate and identify body fluids. However, there are currently no reliable tests to positively identify vaginal material, to differentiate between venous and menstrual blood and to confirm the presence of azoospermic semen. Furthermore, for cases involving allegations of oral intercourse, the attribution of a positive amylase reaction to saliva (as opposed to vaginal secretions) can be problematic.LGC has developed a system that uses the ParaDNA system together with one-tube mRNA detection chemistry for body fluid identification. This can be utilized at the laboratory examination stage, prior to DNA testing, to positively identify body fluids. A series of mRNA markers were selected to positively identify saliva, vaginal secretions, peripheral blood, menstrual blood, seminal fluid and sperm cells. We have carried out an assessment of this system in an active casework environment using mock-case samples. To investigate the sensitivity and specificity of the mRNA markers, the system was tested both by direct sampling of the body fluid stain (using the ParaDNA sampling device), and using aliquots of the retained aqueous supernatant following cell-harvesting.This paper summarises the findings obtained from the initial experiments carried out, together with the results of a further investigation into the effect of mixed body fluid samples on the detection of the individual body fluids.