A number of techniques designed to detect gunshot residues (GSR) on the hands of a suspect or victim have been developed. These techniques range from the now-discredited paraffin test to the more modern techniques which use instrumental analysis or scanning electron microscopy. The limitations of all GSR techniques are that the residues can be removed by rubbing or washing the hands and usually must be collected soon after the firearm is fired, yet even valid GSR tests are not conclusive. The principal problem with the paraffin test is its nonspecificity. The Harrison-Gilroy test, designed to detect primer residues, is not widely used due to its inadequate sensitivity and other drawbacks. Neutron activation analysis (NAA), a method for determining the elemental composition of substances, is extremely sensitive and accurate. However, a principal disadvantage of NAA is the required access to a research nuclear reactor. Other techniques involve atomic absorption, anodic stripping voltammetry, scanning electron microscopy, and trace metal detection technique. 41 footnotes