Identification of gunshot residue: a critical review

A review of the scientific paper published on inorganic gunshot residue (GSR) analysis permits to study how the particle analysis has shown its capability in detection and identification of gunshot residue. The scanning electron microscope can be the most powerful tool for forensic scientists to determine the proximity to a discharging firearm and/or the contact with a surface exposed to GSR. Particle analysis can identify individual gunshot residue particles through both morphological and elemental characteristics. When particles are detected on the collected sample, the analytical results can be interpreted Following rules of a formal general interpretative system. to determine whether they come from the explosion of a primer or From other possible sources. The particles on the sample are compared with an abstract idea of unique GSR particle produced by the sole source of the explosion of a primer. Uniqueness' is not the only problem related to GSR detection and identification for a forensic scientist, With not-unique particles interpretation of results is extremely important. The evidential strength of not-unique particles can increase with a more fruitful interpretative framework based on Bayes rule. For the assessment of the value of a GSR in linking a suspect and a crime. it is important to compare two hypothesis: the first can be that of the evidence if the suspect has been shooting in a specific situation, the second that of the evidence if the suspect was not involved in this shooting. This: case specific or case-by-case approach is closer to what the court is interested in. The authors consider that a case-by-case approach should be followed whenever possible. Research of models and data such as those developed in other tract: evidence material (fibres, glass, etc.) using a Bayesian approach is suggested in the interpretation of GSR. (C) 2001 Elsevier science Ireland Ltd. All rights reserved.