ICP–MS trace-element analysis as a forensic tool

Careful tracing of evidence at the site of a crime must be performed before suspects can be convicted of a crime or homicide. Fingerprints and ballistic control samples are important evidence. A common method used to examine lead bullets is comparison of physical properties such as weight, dimensions, shape, and distinctive markings. However ballistic investigations, for example comparison of characteristic scratches and marks left on fired bullets, do not always give sufficient information. Ballistic abrasion patterns can change for a variety of reasons, e.g. deformation or mechanical strain. Sometimes only particles remain in a victim’s body. In such cases trace-element composition and lead-isotope ratios can be compared with those of controls. Elemental composition of particles and deformed bullets have been compared with the elemental fingerprints and isotope ratios of potential bullet types found on suspects. The applicability of the method was studied for two different cases. Data interpretation and several limitations of the technique are also discussed in this paper.