DNA recovery after sequential processing of latent fingerprints on black polyethylene plastic

Abstract

Latent fingerprints on plastic substrates can be visualized by using sequential treatments to enhance the contrast between the fingerprint residues and underlying substrate; however, the extent to which these processes affect subsequent DNA analysis is mostly unknown. Latent fingerprints deposited on black plastic by one donor were visualized with single-process fingerprint powders (i.e., white powder, bichromatic powder, or bichromatic magnetic powder) or sequential treatments (i.e., laser -> reflected ultraviolet imaging system (RUVIS) -> CA fuming -> RUVIS -> Rhodamine 6G, Ardrox, and MBD (RAM) or CA fuming -> RAM/laser -> bichromatic magnetic powder). Samples were examined after the addition of each treatment. DNA was collected using cotton swabs, extracted, quantified, and amplified. DNA yields, peak heights, number of alleles obtained, and percentage of DNA profiles eligible for CODIS upload were examined. Latent fingerprints processed with the laser and up to three sequential treatments generated DNA profiles with significantly higher peaks heights than those of the untreated samples. Fingerprints processed with the laser and up to two sequential treatments generated DNA profiles with significantly more alleles. All methods beginning with laser enhancement generated more CODIS-eligible profiles. Additional research is needed to determine the extent to which initial laser enhancement impacts the success of downstream DNA profiling results. Although DNA profile development is not guaranteed due to the variable quantities of DNA contained within latent fingerprints, the selection of an appropriate latent fingerprint visualization method could maximize both fingerprint detection and the generation of CODIS-eligible DNA profiles.