An application example of the likelihood ratio approach to the evaluation of organic gunshot residues using a fictional scenario and recently published data

Matthieu Maitre; Mark Horder; K Paul Kirkbride; Anne-Laure Gassner; Céline Weyermann; Anjali Gupta; Alison Beavis; Claude Roux

doi:10.1016/j.forsciint.2022.111267

An application example of the likelihood ratio approach to the evaluation of organic gunshot residues using a fictional scenario and recently published data

Forensic Sci Int. 2022 Jun:335:111267. doi: 10.1016/j.forsciint.2022.111267. Epub 2022 Mar 7.

Authors

Matthieu Maitre¹, Mark Horder², K Paul Kirkbride³, Anne-Laure Gassner⁴, Céline Weyermann⁴, Anjali Gupta¹, Alison Beavis⁵, Claude Roux⁶

Affiliations

¹ Centre for Forensic Science, University of Technology Sydney, PO Box 123, Broadway, NSW 2007, Australia.
² NSW Police Force, Goulburn St, Surry Hills, NSW 2010, Australia.
³ School of Chemical and Physical Sciences, Flinders University, GPO Box 2100, Adelaide, SA 5001, Australia.
⁴ School of Criminal Justice, University of Lausanne, Batochime, 1015 Lausanne, Switzerland.
⁵ Centre for Forensic Science, University of Technology Sydney, PO Box 123, Broadway, NSW 2007, Australia; Faculty of Science, UNSW Sydney, Kensington, NSW 2052, Australia.
⁶ Centre for Forensic Science, University of Technology Sydney, PO Box 123, Broadway, NSW 2007, Australia. Electronic address: claude.roux@uts.edu.au.

PMID: 35339946
DOI: 10.1016/j.forsciint.2022.111267

Abstract

The analysis of gunshot residues (GSR) can provide important information with regard to the involvement of a person of interest (POI) in a firearm-related incident. Organic gunshot residues (OGSR) have been investigated in order to provide additional and complementary information to the traditional inorganic gunshot residue (IGSR) particles detected by scanning electron microscopy (SEM). Currently, many procedures and analytical methods have been developed to detect OGSR-related compounds collected from the shooter's hands. However, such studies provide no information regarding the inclusion of such results in an activity level evaluation for discharging a firearm. The aim of this article is to assess the feasibility of using the likelihood ratio (LR) approach as a tool to evaluate OGSR results for activity level propositions. The developed model focuses on the assignment of an LR for several compounds detected in OGSR. A simple worst-case simulation was investigated in order to assess the applicability of the LR approach to evaluate OGSR traces. This simulation highlighted the importance of addressing an appropriate pair of activity level propositions when evaluating the results.

Keywords: Activity level; Firearm; GSR; Interpretation; OGSR; Weight of evidence.

MeSH terms

Firearms*
Hand
Humans
Microscopy, Electron, Scanning
Organic Chemicals
Wounds, Gunshot*

Substances

Organic Chemicals