SEM/EDS and its Use in the Detection of Gunshot Residue

Gunshot residue (GSR) has been used for decades as incriminating evidence and detecting GSR is critical to its proper use. Previously, chemical tests were the most common method of GSR detection. A novel technique, scanning electron microscopy/electron dispersive x-ray spectroscopy (SEM/EDS), has recently proved viable. Since this technique was foreign to me, I began with an attempt to locate and analyze a GSR particle with previously prepared hand swab samples, then I transitioned to casing swabs to produce more consistent results. Particles with GSR-like characteristics were isolated on the samples and found to be GSR. These particles were difficult to locate due to the lack of GSR particles on the sample disks. Based on my results, SEM/EDS is a viable tool for detecting and analyzing GSR, however, the method of collection needs to be improved. It remains to be determined why the GSR particles were difficult to isolate. Future research will seek to determine this and increase the viability of this type of microscopy.