Gassner, AL, Manganelli, M, Werner, D, Rhumorbarbe, D, Maitre, M, Beavis, A, Roux, CP & Weyermann, C 2019, 'Secondary transfer of organic gunshot residues: Empirical data to assist the evaluation of three scenarios', Science and Justice, vol. 59, no. 1, pp. 58-66.View/Download from: UTS OPUS or Publisher's site
© 2018 The Chartered Society of Forensic Sciences The present study aimed at providing data to assess the secondary transfer of organic gunshot residues (OGSR). Three scenarios were evaluated in controlled conditions, namely displacing a firearm from point A to point B, a simple handshake and an arrest involving handcuffing on the ground. Specimens were collected from the firearm, the hands of the shooter and the non-shooter undergoing the secondary transfer in order to compare the amounts detected. Secondary transfer was observed for the three scenarios, but to a different extent. It was found that displacing a firearm resulted in secondary transfer in <50% of the experiments. The firearm also had an influence, as contrary to the pistol, no secondary OGSR were detected using the revolver. Shaking the hand of the shooter also transferred OGSR to the non-shooter's hand. In that case, the amount of OGSR was generally higher on the shooter than on the non-shooter. Finally, the largest secondary transfer was observed after the arrest with handcuffing with positive results in all cases using the pistol. In that scenario, the amounts on the shooter and the non-shooter were in the same range. This study highlights that the secondary transfer must be taken into account in the interpretation of OGSR. Indeed, an individual's hands might be contaminated by handling a firearm or having physical contact with a shooter.
Maitre, M, Chadwick, S, Kirkbride, KP, Gassner, A-L, Weyermann, C, Beavis, A & Roux, C 2019, 'An investigation on the secondary transfer of organic gunshot residues.', Science & justice : journal of the Forensic Science Society, vol. 59, no. 3, pp. 248-255.View/Download from: UTS OPUS or Publisher's site
Gunshot residues (GSR) are an important forensic trace in firearm-related events. Currently, routine GSR analyses focus on the detection and characterisation of the inorganic components (IGSR). The increasing prevalence of heavy metal-free ammunition challenges these current protocols and there is an increasing interest in how the organic components of GSR (OGSR) can provide complementary information. Similar to the situation with IGSR, OGSR compounds originally deposited on the shooter during the firing process may further be transferred onto another individual or surface. Hence, the aim of this study was to provide additional information regarding the risk of a secondary transfer of OGSR. Two scenarios were investigated, the first one related to the arrest process and the possibilities of a secondary transfer arising between a shooter onto a non-shooter (e.g. between a police officer and a person of interest (POI)). The second scenario concerned the transfer of OGSR onto the non-shooter after handling a firearm for few minutes without discharging it. One calibre was chosen, the .40 S&W calibre, used by several Australian State police forces. A secondary transfer was observed in all cases for the two scenarios investigated, for three compounds of interest: ethylcentralite (EC), diphenylamine (DPA), N-nitrosodiphenylamine (N-nDPA). The firearm handling scenario resulted in a larger secondary transfer to that of the arrest scenario. Overall, the amounts of OGSR detected on the non-shooter were generally lower than that detected on the shooter and controls after the arrest scenario. The results of this study provide complementary knowledge about OGSR, which can be further used to improve the current practice and the interpretation of OGSR evidence. In particular, it highlights that the secondary transfer proposition must be considered during the interpretation of forensic findings, especially when small amounts of OGSR target compounds are detected.
Maitre, M, Horder, M, Kirkbride, KP, Gassner, A-L, Weyermann, C, Roux, C & Beavis, A 2018, 'A forensic investigation on the persistence of organic gunshot residues.', Forensic science international, vol. 292, pp. 1-10.View/Download from: UTS OPUS or Publisher's site
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 compounds well-known as being part of OGSR: ethylcentralite (EC), methylcentralite (MC), diphenylamine (DPA), N-nitrosodiphenylamine (N-nDPA). This study assessed the retention of these OGSR traces on a shooter's hands. The overall project aim was to provide appropriate information regarding OGSR persistence, which can be suitable to be integrated into the interpretation framework of OGSR as recommended by the recent ENFSI Guideline for Evaluative Reporting in Forensic Science. The persistence was studied through several intervals ranging from immediately after discharge to four hours and two ammunition calibres were chosen: .40 S&W calibre, used by the NSW Police Force; and .357 Magnum, which is frequently encountered in Australian casework. This study successfully detected the compounds of interest up to four hours after discharge. The trends displayed a large decrease in the amount detected during the first hour. A large variability was also observed due to numerous factors involved in the production, deposition and collection of OGSR.
Maitre, M, Kirkbride, KP, Horder, M, Roux, C & Beavis, A 2018, 'Thinking beyond the lab: organic gunshot residues in an investigative perspective', Australian Journal of Forensic Sciences, vol. 50, no. 6, pp. 659-665.View/Download from: UTS OPUS or Publisher's site
© 2018 Australian Academy of Forensic Sciences Gunshot residues (GSR) are a common form of evidence in cases involving questions related to the association of a person of interest (POI) to a firearm-related event. GSR analyses currently focus on the detection and characterisation of the inorganic components of GSR (IGSR), which are typically particles composed of lead, barium and antimony originating from the primer. However, certain particles cannot be assigned to IGSR with a high degree of confidence due to possibility of being derived from industrial or domestic sources. Moreover, the increasing prevalence of the use of heavy metal-free ammunition challenges the current protocols used for IGSR analysis. In order to provide complementary evidence to IGSR particles, the current study focused on detecting the organic components (OGSR) arising from ammunition propellant. As the study focuses on the persistence of OGSR, three compounds well known as being part of OGSR were selected: ethyl centralite (EC), diphenylamine (DPA) and N-nitrosodiphenylamine (NnDPA). The study assessed the retention of OGSR traces on a person’s hands up to 1 h after they had discharged a firearm.
Hofstetter, C, Maitre, M, Beavis, A, Roux, CP, Weyermann, C & Gassner, A-L 2017, 'A study of transfer and prevalence of organic gunshot residues.', Forensic Science International, vol. 277, pp. 241-251.View/Download from: UTS OPUS or Publisher's site
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 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.
Maitre, M, Kirkbride, KP, Horder, M, Roux, C & Beavis, A 2017, 'Current perspectives in the interpretation of gunshot residues in forensic science: A review.', Forensic Science International, vol. 270, pp. 1-11.View/Download from: Publisher's site
The traces produced when a firearm is discharged can provide important information in cases when questions regarding a possible association of the firearm with a person of interest (POI), time since discharge or shooting distance are raised. With advances in technology, the forensic challenges presented by these traces, known as gunshot residues (GSR), are moving from the analytical domain to the interpretation of the analytical results. Different interpretation frameworks are currently competing. Formal classification of particles, using standards such as that produced by ASTM, focusses only on evaluation of evidence at the sub-source level. Another approach, based on the application of Bayesian reasoning - namely the case-by-case approach - has been proposed that allows evaluation of evidence in regards to activity-related questions. This alternative approach allows an evaluation of the evidence that is more closely aligned to judicial and investigative aims. This paper critically presents the state of the art in regards to GSR interpretation in a holistic manner.