Investigating the Persistence of Touch DNA on Human Skin in Violent Crime Investigations

This study investigates the persistence of touch DNA on human skin to enhance forensic methodologies in violent crime investigations. Touch DNA, a crucial piece of forensic evidence, can link suspects to crimes through genetic material recovered from skin surfaces. However, the recovery of touch DNA presents unique challenges, particularly concerning the temporal window for effective collection and the influence of environmental factors on DNA preservation. Through a controlled experimental setup, this research explored how the quantity and detectability of touch DNA change over time, with particular attention to the effects of post-deposition activities such as washing. The findings indicate that while the quantity of DNA increases over time, the recovery of alleles from mixed DNA profiles, comprising both victim and perpetrator DNA, faces significant challenges. Notably, alleles from the perpetrator become undetectable after 72 hours (p < 0.05), and environmental interactions further complicate DNA recovery. This study underscores the critical importance of timely evidence collection and introduces considerations for forensic protocols to optimize the recovery and analysis of touch DNA. It also highlights the need for further investigation into how different skin types and individual shedding rates affect touch DNA persistence. Ultimately, this research contributes to the forensic science field by providing insights that can improve the resolution of violent crime investigations through more effective touch DNA recovery strategies.