The effects of fingermark enhancement light sources on subsequent PCR-STR DNA analysis of fresh bloodstains.

This paper describes a study designed to investigate the effects of light sources used to enhance fingermarks on the subsequent polymerase chain reaction (PCR)-short tandem repeat (STR) analysis of bloodstains. Dried bloodstains on glass were exposed for up to 30 min to five different light sources: Argon ion laser, Polilight UV, Polilight green, Superlite, and shortwave UV. The bloodstains were subsequently analyzed using a quadruplex PCR system. It was found that treating the bloodstains with four of the five light sources had no appreciable effect on the results obtained from subsequent PCR analysis. However, exposure of the bloodstains to shortwave UV light for more than 30 s precluded the acquisition of results from PCR testing. Therefore, under casework conditions, it would be preferable to avoid exposing bloodstains, on which PCR typing is to be performed, to shortwave UV.