Gunshot Residue

The presence of gunshot residues on a suspect or suspect’s clothing can tie the suspect to the crime scene. An important forensic application of ultramicroanalysis at McCrone Associates is the searching for gunshot residues by scanning electron microscopy (SEM). Today, very few laboratories have the expertise, experience and instrumentation to conduct these extremely important forensic tests.

Gunshot residues originating from the primers in most cartridges are usually aspherical particles, often very small (<5 micrometers), and contain antimony, barium and lead. They are unique particles and extremely valuable evidence to show that a person recently had contact with or fired a gun.

Samples can be collected directly from the hands and clothing of the suspect onto specially coated SEM stubs. The stubs are then placed in the SEM and/or electron microprobe analysis to search for and identify these unique particles of antimony/barium/lead that indicate gunshot residue.