On the questioned presence of fluorine in inorganic gunshot residue. Case work experience and experimental evidences

Abstract

According to the active ASTM E1588–20 Standard Practice for Gunshot Residue (GSR) Analysis, particles from lead-based primers classified as “characteristic of GSR” will have the chemical composition lead/antimony/barium. Further elements allowed to be incorporated into GSR are explicitly listed in the ASTM guideline. Fluorine is not considered a possible additional element as no common sources of F in shooting related activities have ever been documented. Moreover, presence of fluorine was demonstrated in GSR-similar particles produced by airbag deployments and the possibility to use F as a chemical marker to exclude any discharging of a firearm was consequently suggested. In authors’ case work experience, fluorine containing particles were found on stubs collected from victims’ clothes, discharged firearms and shooters’ hands. Adopting a “case by case” approach, a firearm-related fluorine origin was then sought. Fluorine-based protective lubricants, used both for guns and ammunition components, were experimentally confirmed as a possible source of F in GSR.