ABSTRACT
Doubts initially arose about the particle classification scheme when the NIFSL experienced a case involving the examination of a suspect’s upper outer clothing for FDR, in which the only discharge particle types detected were lead only and barium, calcium, silicon (the barium, calcium, silicon type was considered to be unique to the discharge of a firearm at the time). The size and appearance of the particles were consistent with FDR residue; however, none of the other particle types were detected and test firing of similar ammunition to that used in the incident (same caliber and head stamp) produced the complete range of particle types. In an effort to explain this anomaly it was decided to investigate the suspect’s occupation as a possible source of the particles. Inquiries revealed that the suspect was employed as a general laborer on a building site and that cartridge-operated industrial tools (stud guns) were used on that site. Consequently it was necessary to investigate discharge residue particles from all types of cartridge-operated industrial tools used in Northern Ireland, in order to establish if this was the source of the particles detected on the suspect. The results of the study191 neither proved nor disproved that the use of a cartridge tool accounted for the particles on the suspect, but it did show that the particle classification system needed revision.
