Organic gunshot residues: Observations about sampling and transfer mechanisms (original) (raw)
Related papers
A study of transfer and prevalence of organic gunshot residues
Forensic Science International
The main goal of the present study was to determine the amounts and distribution of organic gunshot residues (OGSR) on the shooter's upper body and clothing after discharging a pistol. A preliminary study was also performed to evaluate the prevalence of OGSR in the general population as well as in a 2 police laboratory environment. In the transfer study, results indicated that OGSR are not only transferred to the hand of the shooter, but also to other parts of the upper body. Thus, wrists and forearms also represent interesting targets as they are washed less frequently than hands. Samples from the face and hair of the shooters resulted in no OGSR detection just after firing. It was also observed that the concentrations recovered from clothing are generally higher compared to the same skin area. Prevalence in both general (n = 27) and police populations (n = 25) was low. No OGSR was detected in the samples from the general population and only two samples from the police population were found positive.
Combined Collection and Analysis of Inorganic and Organic Gunshot Residues
Journal of Forensic Sciences, 2020
Gunshot residues (GSR) analysis and their interpretation provide crucial information on a criminal investigation involving the use of firearms. To date, several approaches have been proposed for the implementation of a combined sampling and analysis of inorganic (IGSR) and organic GSR (OGSR). However, it is not clear at this stage if concurrent analyses of both types of residue might be detrimental to the analysis of IGSR currently applied in forensic laboratories. Thus, this work aims to compare and evaluate three different protocols for the combined collection and analysis of IGSR and OGSR. These methods respectively involve the use of a modified stub (with two halves, one for the detection of IGSR and the other for the analysis of OGSR); the sequential recovery of GSR with two stubs mounted with different adhesives (double-sided carbon tape and Tesa ® TACK) and the sequential analysis of IGSR and OGSR from a single carbon stub following carbon deposition. The detection of IGSR was carried out using SEM-EDX, while OGSR analysis was performed using ultra-high-performance liquid chromatography tandem mass spectrometry (UHPLC-MS/MS). Obtained results for experiments performed using Geco Sinoxid ® ammunition indicated that sequential analysis was the most suitable protocol for the combined collection and analysis of both IGSR and OGSR. A higher number of inorganic (characteristic and consistent) particles and higher concentrations of ethylcentralite, N-nitrosodiphenylamine, diphenylamine and nitroglycerin were recovered with this method.
A forensic investigation on the persistence of organic gunshot residues
Forensic Science International
Gunshot residues (GSR) are a potential form of forensic traces in firearm-related events. In most forensic laboratories, GSR analyses focus on the detection and characterisation of the inorganic components (IGSR), which are mainly particles containing mixtures of lead, barium and antimony originating from the primer. The increasing prevalence of heavy metal-free ammunition challenges the current protocols used for IGSR analysis. To provide complementary information to IGSR particles, the current study concentrated on the organic components (OGSR) arising from the combustion of the propellant. The study focused on four
Forensic science international, 2016
This study aimed at developing a LC-MS method to compare the efficiency of various sampling materials for the collection and subsequent analysis of organic gunshot residues (OGSR). Seven sampling materials, namely two "swab"-type and five "stub"-type collection materials, were tested. The evaluation of sampling materials was systematically carried out by first analyzing blank extracts of the materials to check for potential interferences and determining matrix effects. Based on these results, the best four materials, namely cotton buds, polyester swabs, a tape from 3M and PTFE were compared in terms of collection efficiency during shooting experiments using a set of 9mm Luger ammunition. It was found that the tape was capable of recovering the highest amounts of OGSR. As tape-lifting is the technique currently used in routine for inorganic GSR, OGSR analysis might be implemented without modifying IGSR sampling and analysis procedure.
A new method for collection and identification of gunshot residues from the hands of shooters
Journal of forensic sciences, 2003
This work presents a novel collection method for gunshot residues (GSR) using a sampling procedure based on ethylenediaminetetraacetic acid (EDTA) solution as a complexing agent on moistened swabs. Detection was via a sector-field inductively coupled plasma mass spectrometry (HRICP-MS). The proposed collection and analytical method allowed detection of antimony (Sb), barium (Ba) and lead (Pb) after .38 shot tests. at detection limits of less than 1 microg L(-1) in four different areas of the hands of volunteers. This paper includes a discussion concerning hand areas near the thumb and forefinger as being more suitable for GSR collection as well as a comparison between differences observed using 2% diluted EDTA. 2% nitric acid solution, and simple deionized water as collecting solutions, proving the superior efficiency of EDTA in GSR recoveries.
International Journal of Legal Medicine, 2020
The aim of this work was to characterise three non-toxic ammunition (NTA) from the GECO and Fiocchi brands, which are available in the Italian market. Characterisation was carried out by considering both the elemental chemical composition and morphology, using scanning electron microscopy coupled with energy-dispersive X-ray analysis (SEM-EDS). Particles were collected from both the cartridge cases and the shooters' hands after shooting tests. Six volunteers fired two shots for each ammunition. Several elements, such as aluminium, potassium, silicon, sulphur, titanium and zinc were found in gunshot residue (GSR) particles from different ammunition. We also studied the persistence of these types of GSR on the hands of the shooters in a range between 1 and 6 h after shooting. The GSR particles from the three NTA tested were found on the hands of shooters until 6 h after the shots. The characterisations undertaken in this work will be useful for specialists in forensic science and legal medicine to evaluate trace evidence from these new NTA in casework, as such formulations are in growth.
Surveys of organic gunshot residue prevalence: comparison between civilian and police populations
Forensic Science International
This study investigated the prevalence of eight OGSR compounds in a civilian and a police population. Specimens were collected from the hands and sleeves of 122 civilians and 115 individuals working in police services using carbon stubs. Data was acquired using liquid chromatography coupled to tandem mass spectrometry. Results indicated a non-negligible prevalence in the civilian sample, with 18% of the 122 civilians sampled having one or more OGSR related compounds on their hands and 11.5% on their wrists or sleeves. For the police population, the prevalence was logically higher than for civilians, with 36.5% of the hand specimens and 33% of the wrist specimens positive for one or more compounds. A higher prevalence was expected for the second population due to the possession of service weapons regularly used during shooting exercises. These results demonstrate that the presence of one OGSR compound is not a rare occurrence, even in a civilian population. Considering the results of this research together with information on alternative sources of the targeted OGSR compounds can serve as a basis for OGSR interpretation in casework.
The relevance of gunshot residues in forensic science
WIREs Forensic Science
Gunshot residues (GSR) are routinely exploited by forensic scientists in the investigation of firearm-related events. While many new techniques are daily reported in the literature for the analysis of GSR, there is still a significant lack of data on the transfer, persistence, and prevalence of GSR. Such fundamental knowledge is essential to fully exploit the information potential of GSR for investigation or in Court. This article provides an overview of the relevant questions related to GSR, more particularly to infer about the trace's origin (i.e., is it from a firearm discharge?) and the activity that caused transfer (e.g., primary, secondary, or subsequent transfer). GSR production and composition will be briefly described, considering both inorganic and organic components. Then, the available knowledge about the primary transfer, the secondary transfer, and the persistence of GSR will be outlined, as well as the prevalence (background level) of the targeted elements and/or compounds in the environment, more particularly on the hands of people unrelated to firearm incidents. Finally, the methods developed for the collection, analysis, and interpretation of GSR will be discussed. A holistic approach combining fundamental forensic science knowledge about GSR transfer, persistence, and prevalence together with other available information is discussed as a path forward to increase the relevance and value of the GSR trace in practice.
Analytical and Bioanalytical Chemistry, 2015
In forensic investigation of firearm-related cases, determination of the residual amount of volatile compounds remaining inside a cartridge could be useful in estimating the time since its discharge. Published approaches are based on following the decrease of selected target compounds as a function of time by using solid phase micro-extraction (SPME). Naphthalene, as well as an unidentified decomposition product of nitrocellulose (referred to as "TEA2"), are usually employed for this purpose. However, reliability can be brought into question given their high volatility and the low reproducibility of the extracted procedure. In order to identify alternatives and therefore develop improved dating methods, an extensive study on the composition and variability of volatile residues in nine different types of cartridges was carried out. Analysis was performed using headspace sorptive extraction (HSSE), which is a more exhaustive technique compared to SPME. 166 compounds were identified (several of which for the first time), and it was observed that the final compositional characteristics of each residue were strongly dependent on its source. Variability of single identified compounds within and between different types of cartridge, as well as their evolution over time, were also studied. Many explosion products containing up to 4 aromatic rings were found to be globally present in high proportions. 27 of them (excluding naphthalene) also presented detectable decreases during the first 24 h. Therefore, they could be used as complementary target analytes in future dating methods.
Characterization of volatile organic gunshot residues for dating purposes
Estimating the time since discharge may be a very useful information in the investigation of firearm-related crimes. In order to reach this objective, the study of quantitative decrease of selected volatile organic compounds in barrels or spent cartridges after the shot was generally proposed. Previous studies focused mainly on naphthalene as target molecule. However, organic gunshot residue represents a complex mixture of unaltered gunpowder compounds and explosion products. No comprehensive characterization was performed yet for the latter. The present research aims at determining the composition of gunshot residues in spent cartridges using sorption extraction techniques followed by gas chromatography / mass spectrometry. The aging kinetics of identified volatile compounds was also followed as a function of time. The results of this study will be presented here.