Assessment of gunshot residue detection on a large variety of surfaces by portable LIBS system for crime scene application

The application of Laser-Induced Breakdown Spectroscopy (LIBS) in forensic science has garnered increasing attention. The ability to perform real-time, on-site analysis of Gunshot Residue (GSR) particles and potential elements originating from bullets or projectile cores on various surfaces holds the potential to assist in resolving firearms-related cases. This includes facilitating trajectory determination by locating distinct impact points and identifying the types of ammunition used. This study evaluates the utilization of a portable LIBS device for ballistic forensic purposes. Additionally, it focuses on the assessment of potential false positives and false negatives arising from the different materials where the shots have been fired. Since the system performs laser ablation of both surface particles and the substrate, it emphasizes the importance of conducting preliminary screening in an area with the same composition as the impact zone to minimize potential false positives during direct surface analysis. Furthermore, the results demonstrate the capability to detect the constituent elements of characteristic gunshot residue particles (GSR particles): lead (Pb), antimony (Sb), and barium (Ba) adhering to bullets, as well as the principal elements composing the jacket or core of the projectile: lead (Pb), copper (Cu), and zinc (Zn) through direct analysis, without the need for a sampling kit, on different surfaces such as walls, furniture, or fabrics. Analyses conducted a month after the shots were fired indicate the potential for finding residues in the vicinity of the bullet hole. Analyses conducted a month after the shots were fired indicate the possibility of finding residues in the area around the bullet hole.