Time since contact influences DNA profiling success of cartridges and fired cartridge casings.

Forensic DNA analysis of cartridges and fired cartridge casings remains challenging, possibly due to the heat and pressure generated during firing of the weapon as well as metal ions from the casings that have been suggested to initiate DNA degradation and inhibit PCR during the DNA profiling process. Even though recently developed DNA recovery protocols have shown to significantly improve DNA yields and DNA profile success rates no information is available on whether the time interval between contact and the DNA recovery process has an influence on these outcomes. In the current study 40 cartridges and 40 fired cartridge casings were left untreated for 24 h or 1 week after which the rinse-and-swab technique was used to collect DNA.