Touching Without Contact: Glove-Mediated Secondary DNA Transfer in Forensic Casework

Abstract

The inadvertent transfer of DNA via gloves poses a significant risk to the integrity of forensic evidence, particularly in trace and touch DNA investigations. This study systematically evaluated the extent of DNA contamination on glove surfaces, the effectiveness of common cleaning agents, and the potential for secondary DNA transfer to mock evidence. Twelve participants, pre-classified by DNA shedding status, donned nitrile, latex, and vinyl gloves under controlled laboratory conditions. Glove surfaces were sampled after donning and subjected to four cleaning conditions: no cleaning, 0.3% sodium hypochlorite, RNase AWAY™, and 70% ethanol. DNA was extracted and quantified, and STR profiling was performed to assess the presence and completeness of genetic profiles.

Results demonstrated significant variability in DNA retention based on glove type and cleaning agent. Vinyl gloves retained the highest DNA levels, while nitrile gloves showed the least contamination. Sodium hypochlorite was the most effective cleaning agent, reducing recoverable DNA by up to 94%, followed by RNase AWAY™, with ethanol being the least effective. Notably, even post-cleaning gloves frequently retained sufficient DNA to yield partial STR profiles, underscoring the persistent risk of secondary transfer. Controlled glove-to-cloth contact experiments further confirmed that uncleaned gloves transferred full STR profiles in 80% of cases, while sodium hypochlorite-treated gloves minimized this risk.

Ultraviolet fluorescence visualization revealed contamination hotspots concentrated at the fingertips and palm, highlighting key zones of contact and transfer potential. These findings emphasize the need for standardized glove decontamination protocols, careful selection of glove materials, and contamination-aware handling procedures in forensic workflows. Incorporating these practices will enhance the reliability of trace DNA interpretation and reduce the risk of misattribution in forensic casework.