Raman Spectroscopic Analysis of Organic Gunshot Residue Spanning a Range of Excitation Wavelengths

Gunshot residue (GSR) is a type of trace evidence that can often be recovered at crime scenes. Organic gunshot residue (OGSR) is one of the two major components of GSR. This study investigates the analysis of OGSR, and aims to determine the optimum parameters at which to obtain Raman spectroscopic signals for OGSR particles by varying different excitation wavelengths. In this study, a total of 3 different excitation wavelengths were utilized: 785 nm, 457 nm, and 406 nm. The samples were created by hand selecting OGSR particles and placing them upon a tape substrate. Each of the OGSR particles were cordoned off using a grid formation in order to ensure the clear assignment of spectra to the respective particles

Hierarchical Modelling of Raman Spectroscopic Data Demonstrates the Potential for Manufacturer and Caliber Differentiation of Smokeless Powders

Gunshot residue (GSR) is an important type of forensic trace evidence produced when a firearm is discharged. Currently, inorganic GSR particles are used for establishing the fact of shooting. The organic gunshot residue (OGSR) has been recently shown to have great potential for providing additional information vital for the crime scene investigation. Smokeless powder is the precursor to OGSR and one of its chemical components. In this study, Raman spectroscopy and chemometric modeling were used to analyze smokeless powder extracted from ammunition cartridge cases. The proposed hierarchical model demonstrated great potential for determining the manufacture and the bullet type based on the analysis of smokeless powder. Expanding the developed approach to the analysis of OGSR will be needed to make it a useful tool for law enforcement agencies