Date of Award
Master of Science in Chemical Sciences (MSCB)
Dr. Christopher Dockery
Dr. Michael Van Dyke
Dr. Heather Abbott-Lyon
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 The American Society for Testing and Materials (ASTM) standard ASTM E1588-95 is no longer applicable to such residues.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.