Trace DNA Recovery: Insights from Dubai Police Casework

Abstract

Trace DNA represents a critical form of forensic evidence, frequently recovered from a wide variety of touched or used items. Despite its evidentiary value, trace DNA analysis poses significant challenges due to the minute quantities of DNA involved, as well as the influence of factors such as surface type, collection methods, and environmental exposure. This study systematically examines the success rates and characteristics of trace DNA profiles recovered from six-item categories—tools, stolen items, wearable items, packaging materials, vehicles, and touched items—processed between 2021 and 2023 by the Biology and DNA Section of the Dubai Police Force. A total of 6277 cases were analyzed, encompassing a range of crimes, including homicide, suicide, missing persons, paternity disputes, and burglary. The results demonstrated an overall trace DNA success rate of 64%, with wearable items yielding the highest success rate at 76% and packaging materials yielding the lowest at 54%. Detailed analysis of positive DNA trace samples revealed significant variability in DNA profile types across item categories. Wearable items and touched items predominantly yielded full single (FS) DNA profiles, reflecting their reliability as sources of singular and high-quality DNA. Conversely, stolen items and packaging materials showed a greater prevalence of full mixed (FM) DNA profiles, highlighting their association with complex mixtures due to handling by multiple contributors. Tools and vehicles, meanwhile, exhibited higher rates of partial profiles, presenting unique challenges related to surface irregularities and environmental factors. This study emphasizes the importance of tailoring forensic strategies to item-specific characteristics, as well as the need for systematic mechanisms to categorize trace samples. Addressing operational challenges such as manual sorting and leveraging automation or AI-based systems can further streamline trace DNA analysis. The findings also underscore the importance of data sharing and standardization across forensic laboratories to enhance trace DNA recovery protocols and improve reliability in forensic investigations. Future research should focus on the effects of material properties, environmental exposure, and collection techniques on DNA retention, advancing the field of trace DNA profiling and its applications in forensic science.

Keywords

Forensic science / Trace DNA / Touch DNA / DNA recovery / Cotton swab / PrepFiler Express™ Forensic DNA Extraction Kit / Investigator Quantiplex Pro Quantification Kit / GlobalFiler™ PCR Amplification Kit / DNA profiling / STR analysis / Forensic casework / DNA success rate

Acknowledgments

Sincere appreciation is extended to colleagues within the Biology and DNA Section for their unwavering dedication and support throughout this study. Special thanks are also due to the co-authors of this manuscript, whose contributions were instrumental in shaping the study and its findings. Furthermore, profound gratitude is directed towards Ahmad Thani bin Ghalita, the Director of Dubai Police’s General Department of Forensic Science and Criminology, for his invaluable assistance and steadfast commitment to promoting research and facilitating data sharing. The authors would like to express their deepest thanks to Ahmed A. Abdullahi and Nashmi I. Aidarous for their exceptional work in organizing case data over the years. Their meticulous efforts and dedication were critical to the successful completion of this study, and without their contributions, this research would not have been possible.

Author Contributions

Conceptualization: S.K.A. and W.G.; Methodology: S.K.A.; Formal Analysis: S.K.A.; Investigation: S.K.A.; Data Curation: S.K.A., A.A.A., N.I.A. (Nashmi I. Aidarous), H.M.A., A.M.A. (Amna M. Alrazouqi), A.M.A. (Alanoud M. Alsaadi), S.M.A., A.F.A., N.I.A. (Noura I. Aldabal), M.A.A. and M.M.S.; Writing—Original Draft Preparation: S.K.A.; Writing—Review and Editing: S.K.A. and W.G.; Visualization: S.K.A.; Supervision: H.J.A.

Ethics Statement

Not applicable.

Informed Consent Statement

Not applicable.

Funding

This research received no external funding.

Declaration of Competing Interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

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