Vibrational Spectroscopy of Gunshot Residue

As submitted by the proposer:
The ultimate long-term goal of this project is to develop a novel, non-destructive, easy-to-use, rapid and on-field technique for the detection and characterization of gunshot residue (GSR) via applied vibrational spectroscopy combined with advanced statistics. This introductory study will work on the characterization of GSR and will target the elucidation of forensically relevant parameters associated with the ammunition which was discharged. Thus, the emerging method targets a link between the GSR recovered from a crime scene, to a specific type (chemical composition or other) of ammunition. However, the capability to eliminate a type of ammunition as generating a crime scene GSR sample must first be accomplished. To achieve these goals, the relationship between the discharged ammunition and their subsequent GSR will be investigated. These investigations will include the chemical analysis of the unburnt ammunition material (propellant and primer mixtures). Ammunition from different manufaturers will be disassembled an the propellant analyzed using Raman and IR. The ammunition will be discharged and the subsequent GSR will be collected. We will investigate the impact of each chemical variation within the ammunition propellant and primers, on their subsequent GSR. The proposed approach is based on the hypothesis that the firearm discharge process can be considered as a complex chemical reaction in which forensically relevant parameters, such as the chemical composition of the propellant and primer represents reagents, and the firearm/ammunition combination determines the reaction conditions. As such, the chemical composition of GSR should depend on the ammunition propellant and primer composition. The end goal of the project targets the ability to identify the specific ammunition which was discharged at a crime scene via GSR analysis. No current or developing method can achieve this goal based upon GSR analysis. Additionally, an approach combining tape lifting and automated Raman microspectroscopic mapping will be investigated as a novel approach for the collection and detection of GSR. This emerging technique has the potential to enhance the evidentiary value of GSR. When fully developed, this combined approach may provide forensic investigators with a new avenue for crime scene shooting incident reconstruction. Vibrational spectroscopy, known for its high selectivity, will be combined with advanced statistical analysis to evaluate the specificity of GSR chemical composition and how it relates to the original ammunition composition.

Note: This project contains a research and/or development component, as defined in applicable law.

ca/ncf