Date of Award

Spring 5-10-2016

Track

Chemistry

Degree Type

Thesis

Degree Name

Master of Science in Chemical Sciences (MSCB)

Department

Chemistry

Committee Chair

Dr. Christopher Dockery

Committee Member

Dr. Michael Van Dyke

Committee Member

Dr. Heather Abbott-Lyon

Abstract

The analysis of gunshot residue (GSR) has been forensically relevant for many years and several methods are well characterized in scientific literature. However, the manufacture and distribution of lead-free alternatives to small caliber firearms ammunition is increasing rapidly as these types of rounds are more environmentally friendly and safer for use in indoor shooting ranges. Removing lead-containing compounds (e.g., lead styphnate) from the primer mixture eliminates a significant chemical marker vital to the legal precedent governing GSR analysis. The American Society for Testing and Materials (ASTM) standard ASTM E1588-95 is no longer applicable to such residues. With this emerging market, the forensic community must develop and validate methods aimed at the detection of lead-free GSR on the hands of suspected shooters. This study investigated the use of Laser-Induced Breakdown Spectroscopy (LIBS) and Scanning Electron Microscopy Energy-Dispersive X-ray Spectroscopy (SEM-EDX) as means of characterizing simulations of lead-free primers and GSR originating from the discharge of lead-free blank training rounds, typically used by law enforcement. As a result, forensic investigators will be provided with: a chemical profile for lead-free GSR using LIBS; the fully characterized rates of error associated with this method for shooters and non-shooters; and the lifetime that forensically relevant quantities of lead-free GSR can be recovered from the hands of a suspected shooter. Additionally, this study serves as the first recorded comparison in the analysis of lead-free GSR via LIBS as a rapid and relatively non-destructive screening method followed by confirmation with SEM-EDX on the preserved evidence.

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