Detection of firearm imprints on the hands of suspects: effectiveness of PDT reaction

Pyridyldiphenyl triazine (PDT) and three of its analogues were compared as practical reagents for visualizing unseen impressions left on the hands of a person who has held a firearm. The parent compound, PDT, gave the best results using intensity and clarity as measuring criteria. The effectiveness of the PDT reaction was then studied on 147 volunteers who had held firearms in their hands. Identifiable impressions of the metallic parts of the weapons were developed on the hands of 103 volunteers (70%). Results with females were slightly higher than with males, however, the difference was possibly statistically insignificant, and needs further study. Ferroprint and Ferrotrace, 5 commercial preparations that are based on the PDT reaction, have become a part of the professional equipment of every crime scene technician in Israel.