A Novel Two-Step Method for the Detection of Organic Gunshot Residue for Forensic Purposes: Fast Fluorescence Imaging Followed by Raman Microspectroscopic Identification

Abstract

Gunshot residue (GSR) is potentially key evidence during a criminal investigation of a shooting accident. Current standardized forensic science methods target the detection of inorganic GSR (IGSR). In this proof-of-concept study, a new two-step method for the detection and identification of organic GSR (OGSR) is proposed. This method utilizes highly sensitive fluorescence hyperspectral imaging of a sample area to detect potential GSR particles, followed by confirmatory identification of the detected particles using Raman microspectroscopy. In this study, two different GSR samples on adhesive tape substrates were created. One sample was made by manually placing a known amount of OGSR particles onto an adhesive tape substrate. The second sample mimicked a real crime scene situation and had an unknown number of GSR particles mounted onto an adhesive tape substrate using a most common tape-lifting procedure for the recovery of GSR from the skin of a suspect and other surfaces. These two samples were subjected to the developed twostep analysis method. It was found that this method was accurately able to detect and identify all OGSR particles. Representative spectra of OGSR particles showed characteristic Raman peaks at 850 cm −1 , 1287 cm −1 , and 2970 cm −1 . This methodology offers a promising means to meet current needs within the framework of GSR analysis by providing a way to accurately detect and identify OGSR.

Interpol Review of Gunshot Residue 2019 to 2021

“…Khandasammy et al however, take in Ref. [ 94 ] the approach to detect the particulate OGSR using a two-step hyperspectroscopic technique. In a first step, the potential OGSR particles are detected by scanning the sample surface using a 455 nm laser source at a 10X objective magnification.…”

Magnetic carbon nanoparticles derived from candle soot for SALDI MS analyses of drugs and heavy metals in latent fingermarks

“…Residue generated in GSR, either organic or inorganic, can easily adhere to the hand, hair, face, clothes, nasal mucous of a shooter and other object or person nearby. Analysis of these residues can help to investigate whether the shooting has actually occurred and estimate the shooting distance [46]. Additionally, metallic GSR originating from ammunition (Pb, Sb, Ba, etc..) can stick to LFM which may enable the link between the biometric information and the circumstances of the offence.…”

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

“…Visual inspection was also conducted to ensure that no burning or damage would be incurred to the sample. The laser excitation of 457 nm was selected based on a previously completed study to minimize fluorescence interference [24]. Various exposure times, accumulations, and laser power settings were tested and compared in order to ensure the optimal Raman signal-to-noise ratio was attained without damaging the sample.…”