Sexual-assault DNA workflows are structured around a semen-centric model in which semen provides a rich source of male (perpetrator) DNA that can be separated from the epithelial (victim) contribution through differential lysis. However, as routinely implemented, differential lysis is labor-intensive and prone to incomplete fractionation, while cell-type–based contributor separation is increasingly challenged by evidentiary contexts that violate its underlying assumptions. These include assaults with epithelial-only contact (e.g., digital penetration, fondling), mixtures containing semen from multiple male assailants, and scenarios in which semen cannot be recovered (e.g., condom use). Together, these conditions indicate a growing mismatch between established workflows and the biological realities of sexual-assault evidence—one that remains insufficiently examined from a practitioner-informed, operational perspective. 

To address this gap, this study provides a systematic analysis of sexual-assault DNA casework based on a survey of practitioners from 40 forensic laboratories, predominantly large European forensic service providers. The survey captures practices across the evidentiary chain—from sexual assault examination and evidence intake to semen screening, differential DNA extraction, and DNA profiling—and examines the operational logic underpinning these workflows. This includes evaluating the continued reliance on methods such as manual differential lysis, asking whether their persistence reflects specific investigative utility or institutional inertia. 

The study then examines how the described operational practice is challenged by sexual-assault evidence. Particularly, it identifies evidentiary features associated with analytical difficulty, including the nature of sexual contact, the evidentiary substrate sampled, and case circumstances that depart from the single-donor, semen-centric paradigm. It further assesses how laboratories respond to these constraints and at what operational cost. This input–response analysis reveals both the resilience embedded in existing workflows and challenges that persist despite substantial compensatory effort. 

Finally, the study captures practitioner perspectives on desired innovation in sexual-assault DNA casework and links these priorities to constraints identified through operational analysis. By aligning expressed needs with inferred constraints, it highlights priority directions for technological development that are both end-user driven and practically-grounded. 

Authors

• Malika Dosmagambetova (Institute of Legal Medicine, Medical University of Innsbruck, Austria) 
• Bram Bekaert (KU Leuven, Department of Imaging & Pathology, Forensic Biomedical Sciences; LISCO, The KU Leuven Institute for Single Cell Omics; UZ Leuven, Laboratory of Forensic Genetics, Belgium) 
• Athina Vidaki (Maastricht University, GROW and CARIM Institutes, Department of Genetics & Cell Biology; Maastricht University Medical Center, Department of Clinical Genetics, Netherlands) 
• Walther Parson (Institute of Legal Medicine, Medical University of Innsbruck, Austria)