Modified Firearm Discharge Residue Analysis utilizing Advanced Analytical Techniques, Complexing Agents, and Quantum Chemical Calculations

Abstract

The use of gunshot residue (GSR) or firearm discharge residue (FDR) evidence faces some challenges because of instrumental and analytical limitations and the difficulties in evaluating and communicating evidentiary value. For instance, the categorization of GSR based only on elemental analysis of single, spherical particles is becoming insufficient because newer ammunition formulations produce residues with varying particle morphology and composition. Also, one common criticism about GSR practitioners is that their reports focus on the presence or absence of GSR in an item without providing an assessment of the weight of the evidence. Such reports leave the end-used with unanswered questions, such as “Who fired the gun?” Thus, there is a critical need to expand analytical capabilities and enhance the impact of the forensic scientist’s conclusions. To maximize the evidential value of GSR evidence, detection methods exploiting modern advancements in instrumentation must be explored and developed. This collection of work reviews the current literature review and illustrates a trend to investigate emerging methods to enhance IGSR analysis with a wider emphasis on OGSR compounds. Combining IGSR and OGSR components increases the confidence of detecting GSR on a collected sample. Overall, the development of novel analytical methods for GSR detection, the application of ground-breaking statistical methods to interpret GSR evidence using artificial intelligence (neural networks) and likelihood ratios to estimate the weight of the evidence, and the understating of the host-guest chemistry of GSR species is anticipated to provide a needed leap of knowledge in the community.