A Universal Method for the Detection of Gunshot Residue using Vibrational Spectroscopy

Gunshot residue (GSR) is a type of trace evidence that comprises particles left on hands, clothing, or surfaces following firearm discharge. It consists of organic and inorganic compounds, including partially burned propellant, primer, and cartridge case materials. GSR analysis is vital in criminal justice, providing crucial evidence in shooting-related cases. GSR is categorized into organic (OGSR) and inorganic (IGSR) types, differing in chemical composition and particle size. A current method of choice, SEM/EDS is used for IGSR analysis only and is costly, destructive to the sample, and time-consuming. There is a great need for a confirmatory and non-destructive method for the detection of both OGSR and IGSR. Raman spectroscopy emerges as a promising tool to achieve this unmet need. The purpose of Goal 1 is to develop an in situ method for the detection and confirmatory identification of GSR particles on common substrates based on fast fluorescence mapping followed by Raman microspectroscopy. The method will be optimized for the detection of GSR particles trapped inside common fabrics. The latter capability will be of great importance because such trapped particles are more likely not to be lost with time and/or cleaning. In addition, these particles are not likely being collected using conventional adhesive tape/disc and, as such would never be detected using conventional methods. The developed approach will be tested for potential false positives caused by environmental contaminants. The purpose of Goal 2 is to expand the method to the detection of GSR particles on adhesive substrates used for collection of GSR from surfaces and hands. A successful completion of Goals 1 and 2 will make the proposed method universal, since it will be applicable for both OGSR and IGSR, and could be used both in situ on common fabric and on adhesive tape/disc. The purpose of Goal 3 is to conduct an exploratory study of using a portable instrument for the detection and identification of GSR, with potential application at the crime scene. The NIJ grant will support this research for five years contingent upon semi-annual reports and a final report submitted at the conclusion of this research. It is anticipated that publications and presentations will be produced from the results gathered during this grant. Our study is supported by our collaborators and consultants from the New York State Police Forensic Investigation Center in Albany. CA/NCF