Rapid Detection of Gunpowder Residue between a Pistol and a Revolver on Hands and Sleeves: A Field Method Using a Digital Scope with Microimaging Technology

In the U.S., shooting-related incidents continue to rise.Both gunshot residue (G.S.R.) and gunpowder residue (G.P.R.) have long been used to detect their presence to determine the involvement of an alleged shooter, yet they are barely visible by the naked eye.While some methods have been reported, such as the Sodium Rhodizonate/Modified Griess methods and the Scanning Electron Microscope (SEM), they are either nonapplicable on human skin at scenes or the SEM is a lab-based device and too expensive beyond most police crime lab budgets, which is an indicator of a lack of field-based devices to detect the G.S.R./G.P.R. on their dimensional differences on landing surfaces (hands and sleeves).Under a quasi-experimental design with purposive sampling, a digital device (the DM series) with microimaging technology was able to compare and differentiate the four stubs (N=4) between a pistol (Glock 19) and a revolver (.38 S&W) at the three morphological characteristics: unburnt, semi-, and completely burnt G.P.R. residues.Further, the digital device was also capable of differentiating the G.P.R. particles at three levels: between the pistol and the revolver, between two hands and two sleeves, and between the G.P.R. and associated fibers.The study findings indicate the digital scope can visualize the invisible G.P.R. particles on the hand and the sleeve and thus may provide a supplementary method prior to the Sodium Rhodizonate/Modified Griess methods and the Scanning Electron Microscope in a quick, real-time, non-destructive, and in-situ manner for a presumptive result.