Comprehensive Assessment of Novel Reference Materials and Analytical Methods for the Analysis and Interpretation of Organic and Inorganic Gunshot Residues

Classic inorganic gunshot residue analysis (IGSR) relies on standardized protocols that provide confidence to practitioners when conducting these examinations. However, the evolution of ammunition to greener alternatives and technological advances are changing the identification and interpretation paradigms. Organizations like NIST/OSAC and NIJ/TWG have reported relevant gaps in this field. For instance, the development of technologies that offer extended detection to include non-traditional organic markers (OGSR). Also, access to reference materials that can lead to harmonized QC policies across laboratories. Finally, the demand for interpretation models that incorporate analytical data, collection, deposition, and persistence information to assess the weight of the evidence. We aim to address those priorities by developing solutions that increase the reliability and efficiency of GSR examinations. We propose to do that by building capacity with emerging methods and standard materials to increase the quality and usage of data. Our specific goals are; first, design characterized organic and inorganic GSR reference standards representative of modern ammunition for research and crime laboratories. This tailor-made standard will be applicable for QC, validation of existent and new methods, and interlaboratory testing. Second, to develop novel routes for studying transfer and persistence of IGSR and OGSR using our tailor-made standard. To this end, a known number of characterized GSR particles will be deposited on over 600 individuals under systematic and controlled conditions to evaluate different factors that affect GSR retention (e.g., activities, time, ammunition, and clothing types). Third, to compare the performance and cost-efficiency of portable and bench-top LIBS and electrochemical systems, using over 1000 authentic GSR samples and standards, through a strategic collaboration with industry and practitioners. This comparison would expand the utility of the methods to an on-site testing platform currently unavailable in the field while transforming case management and decision-making processes. Finally, we propose to apply statistical methods for the interpretation of GSR evidence considering probabilistic approaches and Bayesian networks, using the data from our extensive population database and the persistence study. Our proposal not only addresses several needs in the field but also responds to more than one of the national priorities identified by NIJ: a) educating and training a future workforce, b) transferring technology from laboratory to marketplace, and c) partnering with industry and academia. This study will provide a robust platform for training the next generation of forensic scientists and for future applications to the collection, examination, and interpretation of evidence in the criminal justice system. Note: 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