Uncovering the Persistence of Touch DNA on human skin and its implications for violent crime investigations

Abstract

This study investigates the persistence of touch DNA on human skin to enhance forensic methodologies in violent crime investigations. Touch DNA, a critical piece of forensic evidence, can link suspects to crimes through genetic material recovered from skin surfaces. However, its recovery presents challenges, particularly regarding the temporal window for effective collection and the impact of environmental factors on DNA preservation. Through a controlled experimental setup, this research examined how the quantity and detectability of touch DNA change over time, with a focus on the effects of post-deposition activities such as washing. The findings reveal that while DNA quantity increases over time, recovering alleles from mixed DNA profiles—comprising both victim and perpetrator DNA—becomes increasingly difficult. Notably, alleles from the perpetrator become undetectable after 72 hours (p < 0.05), and environmental interactions, such as washing or sweating, further complicate recovery. This study underscores the importance of timely evidence collection and proposes considerations for forensic protocols to optimize touch DNA recovery and analysis. It also highlights the need for further investigation into how skin type and individual DNA shedding rates affect touch DNA persistence. Ultimately, this research contributes valuable insights that can improve the resolution of violent crime investigations through more effective DNA recovery strategies.