Examination of the potential for glass-containing gunshot residues to improve forensic gunshot residue interpretation

Author: Kelsey Elaine Seyfang

Seyfang, Kelsey Elaine, 2019 Examination of the potential for glass-containing gunshot residues to improve forensic gunshot residue interpretation, Flinders University, College of Science and Engineering

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Abstract

Guns were used in crimes amassing over 24 thousand victims in Australia between 1995 and 2012, including 859 homicides. A common trace evidence in these cases is gunshot residue (GSR), a mix of vapours and particulates that are deposited onto the shooter, victim, and surrounds during a firing event.

There is currently difficulty in distinguishing between residues from different sources, such as from a firearm and fireworks or nail guns, of GSR from two different ammunitions. A potentially highly characteristic particle ‘glass-containing GSR’ (gGSR) has been discovered previously, and in order to improve fundamental understanding of this type of GSR, and to explore novel capabilities offered through analysis of these particles, a three-pronged project was undertaken.

The first examined the probative value of glass-containing GSR by investigating potential sources of similar particles, including from brake pads, fireworks and nail guns. This project focussed on incorporating gGSR particles into GSR investigations using techniques currently used in research and casework, and improving the detection of and discrimination between samples of GSR using gGSR.

Secondly, a marked survey was undertaken on glass particles taken from different ammunition. The variation of frictionator glass and glass-containing GSR from ammunitions across the Australian marked was assessed, focussing on 0.22 rimfire weapons. It was found that with 99% confidence, over 94% of glass samples from ammunitions from different brands could be distinguished.

In the third sub-project, genuine glass-containing GSR particles were located, and methods for the analysis and comparison of these samples were investigated. It was found that different glass-containing particles had different morphologies, and different incorporation of other GSR components. It was also demonstrated, as a proof-of-concept, that pre-fired and post-fired residues from the same ammunition could not be discriminated, while residues from different sources could potentially be discriminated, while residues from different sources could potentially be discriminated.

The results from each of these parallel prongs have inter-connecting and overlapping consequences for interpretation of GSR evidence and could lead to the development of new capabilities and opportunities in forensic laboratories.

Keywords: Gunshot Residue, GSR, gGSR, glass, ToF-SIMS, SEM-EDS, Forensic Science, Advanced Chemical Analysis, X-ray Microanalysis

Subject: Forensic & Analytical Chemistry thesis

Thesis type: Doctor of Philosophy
Completed: 2019
School: College of Science and Engineering
Supervisor: Paul Kirkbride