Destructiveness of latent print processing techniques to DNA analysis

Forensic laboratories seek to maximize the evidentiary value of items examined by multiple disciplines, such as DNA and latent prints. However, many latent print development techniques are considered detrimental to DNA recovery. Previous studies evaluated the effects of latent print processing on DNA recovery; however, these studies relied on natural fingerprints, which inherently contain variable amounts of DNA. Consequently, it remains unclear whether observed differences in DNA recovery following latent print processing reflect the effects of the processing techniques or simply variation in the initial quantity of DNA deposited. This study standardized DNA deposition quantities by applying 5 μL of sterile sebum-eccrine solution and 1 μL of 5 ng/μL of DNA in solution to glass, paper, fired brass cartridge casings, and the adhesive side of tape to simulate fingerprints containing a known quantity of DNA. Samples were processed using ninhydrin, 1,2-indanedione, cyanoacrylate fuming, rhodamine 6G, Basic Yellow 40, Wetwop, physical developer, RUVIS, and acidified hydrogen peroxide. DNA quantities from all techniques were then compared to samples that did not undergo latent print processing to evaluate the effects on DNA recovery. No DNA contamination was detected in the latent print processing techniques. Significant reductions in DNA recovery were observed following treatment with 1,2-indanedione, ninhydrin, physical developer, RUVIS, Basic Yellow 40, Wetwop, and acidified hydrogen peroxide. Cyanoacrylate fuming and rhodamine 6G did not significantly affect DNA recovery. These findings establish clear boundaries for optimal sequential evidence workflows. By identifying which latent print techniques preclude successful downstream DNA processing and analysis, laboratories can eliminate futile evidentiary processing, thereby conserving time and financial resources.