Smoking Gun or Red Herring?

A New Scientist investigation has revealed that finding gunshot residue on a suspect doesn’t necessarily mean they fired a gun. Gunshot residue analysis is used by forensic scientists around the world. It is based on identifying combinations of heavy metals in microscopic particles that are formed when the primer in a cartridge ignites. However, recent research shows that someone who has never fired a gun can be contaminated by someone who has. What is more, it is even possible to pick up incriminating particles from entirely innocent sources