Investigating Touch DNA Success Rates in Vehicle Sites for Hit-and-Run Casework

Abstract

This study evaluated the effectiveness of Touch DNA recovery from four key vehicle contact points—steering wheel (SW), gear shift (GS), interior door handle (IDH), and exterior door handle (EDH)—in the context of hit-and-run forensic casework. 1769 samples were collected from 359 vehicles processed between 2020 and 2023. Statistically significant differences were observed in the quantity and quality of DNA recovered across these sites (p < 0.05). The steering wheel yielded the highest DNA success rates, followed by the gear shift, whereas the exterior and interior door handles demonstrated substantially lower recovery efficiency. These findings underscore the critical role of strategic sampling site selection in maximizing evidentiary outcomes. The results support prioritizing the steering wheel and gear shift as primary targets for DNA collection in vehicle-based investigations. The study highlights the practical utility of Touch DNA in linking individuals to vehicular crimes and calls for further research into alternative sampling techniques and contamination control measures to optimize forensic DNA recovery protocols in real-world hit-and-run scenarios.

Keywords

Forensic genetics / Forensic science / DNA profiling / Trace DNA / Touch DNA / DNA recovery / Hit-and-run casework / Vehicle DNA collection / Forensic casework / DNA success rate

Acknowledgments

We wish to express our deep appreciation to our colleagues in the Biology and DNA Section at the General Department of Forensic Science and Criminology, Dubai Police, for their invaluable support and collaboration throughout the course of this study. Special thanks are extended to Major General Ahmad Thani bin Ghalita, Director of the General Department of Forensic Science and Criminology, whose exemplary leadership and steadfast encouragement played a pivotal role in facilitating and advancing this research.

Author Contributions

S.K.A. was responsible for sample collection, data analysis, and drafting the main manuscript, as well as writing—review and editing. N.I.A. (Nashmi I. Aidarous), A.A.A., H.M.A., A.M.A. (Amna M. Alrazouqi), A.F.A., S.M.A., A.M.A. (Alanoud M. Alsaadi), N.I.A. (Noura I. Aldabal), and M.A.A. contributed to sample collection, data analysis, and visualization. H.J.A. was responsible for conceptualization and supervision. All authors have read and approved the final version of the manuscript and participated in the revision process.

Ethics Statement

This study was carried out in accordance with the ethical guidelines established by the General Department of Forensic Science and Criminology, Dubai Police General Headquarters, Dubai, UAE. The research protocol, including data collection and analysis procedures, was reviewed and approved by the Department to ensure adherence to both institutional and international ethical standards (Ref. No. STEMH 912, May 2024). All aspects of the study were conducted with a commitment to maintaining the highest levels of scientific integrity and ethical responsibility, with the objective of contributing to the advancement of forensic science practice.

Informed Consent Statement

Not applicable.

Data Availability Statements

Not applicable.

Funding

This research received no external funding.

Declaration of Competing Interest

The authors declare no conflicts of interest. There are no known financial or personal relationships that could have influenced the research, analysis, or conclusions presented in this study.

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