Gunshot residue (GSR) involves the deposition of metal particles emitted from a firearm after the rapid heating and cooling from the combustion reactions. The formation of a single spherical particle containing lead, barium, and antimony is characteristic of GSR. Among the challenges in the validity of this evidence are the inconsistencies of the transfer and persistence of these particles. Specifically, the secondary transfer and persistence of GSR on various fabrics are of forensic relevance. The elemental detection and quantification of these metals at trace levels are required for evidentiary analysis of gun-related crimes. Herein, metal transfer and persistence on various fabrics were evaluated using MP-AES and ICP-MS instruments in tandem. Fabric wipes of a firearm after a known number of shots deployed were provided from the Center of Forensic Sciences. Gun range field samples were collected on various fabrics from the hands of three test subjects and the barrel of a Savage model 5 .22 caliber rifle repeater. The fabrics used for sample collection at the gun range are cotton, polyester, elastane, viscose, and denim. Persistence studies are predicted to deviate between fabrics. Transfer studies are probed by designated area exposure to GSR to monitor the transfer within the same fabric in evidence packaging, and probed transfer was induced by agitation of a contaminated and clean cloth in an evidence bag. The extraction protocols were optimized and samples were analyzed using both instrumental methods. Metal deposition heat maps are used to monitor where GSR deposits on the contaminated cloths. Metal concentration deviations were observed in whole cloth concentrations indicating shot to shot variation. All metals were found during transfer studies. Data presented will provide additional insight into GSR transfer and persistence on various fabrics.

Transfer and persistence studies of gunshot residue on fabrics analyzed by MP-AES and ICP-MS

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