Fast Screening of Firearm Discharge Residues by Laser-based Spectrochemical Methods, Electrochemical Sensors, and Chemometrics

The detection of firearm discharge residues (FDR) provides valuable information in cases involving homicides, suicides, accidental shootings, and terrorism. Despite the scientific validity of this discipline, there are persisting challenges regarding the speed of analysis, preservation of the evidence, and interpretation of results. Consequently, there is a critical need to develop methods that can improve the response time and reliability of these determinations.

Our overall purpose is to develop a comprehensive approach to overcome these significant concerns and to enhance current capabilities in the criminal justice system. This project aims to develop and validate fast tests-LIBS and electrochemical sensors-for FDR detection and statistical models for the quantitative interpretation of the evidence.

Our central hypothesis is that electrochemistry and LIBS will provide screening methods that are quicker, more selective, and more informative than current assays. A notable advantage of these methods is the capability to conduct laboratory-based analysis and field detection of both inorganic and organic components. Also, LIBS can identify a more substantial number of elements used in modern ammunition and generate 3D-chemical images of the spatial distribution of FDR for more objective estimations of shooting distance, identification of bullet holes and scanning of large areas. These assays are expected to offer a cost-effective strategy to complement traditional SEM-EDS methods and color tests that are widely utilized in forensic laboratories. Time of analysis is substantially reduced from hours/days to just a few minutes, and therefore these methods are anticipated to offer a streamlined process and lower error rates associated with contamination and persistence.

The proposed methodologies will be validated through a set of 552 samples and 100 in-house GSR control standards. The first collection consists of 375 samples.

This project contains a research and/or development component, as defined in applicable law, and complies with Part 200 Uniform Requirements - 2 CFR 200.210(a)(14).

CA/NCF