AFTE Store - The Effects on Firearm Identification from a Proposed Latent Fingerprint Technique for Fired Cartridge Cases

Fired cartridge cases are a difficult surface to successfully recover latent fingerprints. The difficulty with this surface arises from the small curved surface area and the friction ridge contact on the cartridge case from being loaded, fired, extracted and ejected from a firearm. A new technique has been offered for recovering latent fingerprints from fired cartridge cases. This technique involves heating a fired cartridge case to an elevated temperature of about 600o to 700oC in order to help corrode the print to the cartridge case. This corroded print is then enhanced by a dusting technique involving an electrical current and charged microspheres with a fine dust on them. Heating metal causes expansion and contraction as well as oxidation. This paper studies the effects of the heating process on fired cartridge cases. The results from this study suggest that as cartridge cases are heated, the minute detail on the breech face markings appear less crisp and more smoothed. No false identifications or eliminations were made due to the heating, however a significant increase in the amount of inconclusive results were noted. The most difficult comparisons were found to be on cartridge cases that were heated to 800oC. Due to the increased difficulty in comparisons, it is not suggested to heat cartridge cases for any type of examination if further comparison examinations are required.