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Objectives <p>The detection and persistence of biological evidence in child sexual abuse cases are critical in forensic practice, particularly when delays in presentation or post-incident actions may compromise DNA recovery. This study evaluated the forensic yield of swab, clothing, and crime scene examinations in relation to post-incident time interval (PIT), anatomical region, victim post-incident actions, and autosomal STR and Y-STR analyses.</p> Methods <p>This retrospective study examined 417 swab samples (361 anogenital, 56 body surface), 68 clothing, and 22 crime scene examinations from 136 child sexual abuse cases. Molecular analysis results were obtained from official forensic laboratory reports. PIT was categorized as Day 0, Days 1–3, and Days 4–10. Post-incident actions, including bathing and clothing change, were recorded.</p> Results <p>DNA positivity was defined as the recovery of an interpretable male DNA profile, based on autosomal STR analysis and/or a reportable Y-STR haplotype, that was not attributable to the victim. Among cases, DNA positivity was detected in 20/136 (14.7%) with swab samples, in 54/68 (79.4%) with clothing submissions, and in 18/22 (81.8%) with crime-scene submissions. DNA positivity of the swabs was observed between 5 and 110&#xa0;h post-incident, with the latest detection obtained from an internal anal (dry) swab. Bathing was associated with descriptively lower swab DNA detectability, whereas no statistically significant association was observed for clothing change.</p> Conclusions <p>Although DNA detectability decreases with increasing PIT, biological evidence—particularly from anogenital samples—may persist beyond the commonly applied 72-hour window. DNA positivity was more frequently observed in external anogenital swabs (vulvar and perianal) than in internal swabs (vaginal and anal). This finding should be examined with an extended sample size. Y-STR analysis enhanced detection in low-template or autosomal-negative cases, supporting comprehensive evidence collection regardless of PIT or post-incident actions.</p>

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Forensic DNA yield from swab, clothing, and scene samples in acute child sexual abuse cases: a retrospective study from a child advocacy center in Türkiye (2019–2022)

  • 期刊论文

  • 发表日期：

    2026年7月23日

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  • Özlem Durma,
  • Sıtkı Tıplamaz,
  • Fatih Hitami Usluoğulları

摘要

Objectives

The detection and persistence of biological evidence in child sexual abuse cases are critical in forensic practice, particularly when delays in presentation or post-incident actions may compromise DNA recovery. This study evaluated the forensic yield of swab, clothing, and crime scene examinations in relation to post-incident time interval (PIT), anatomical region, victim post-incident actions, and autosomal STR and Y-STR analyses.

Methods

This retrospective study examined 417 swab samples (361 anogenital, 56 body surface), 68 clothing, and 22 crime scene examinations from 136 child sexual abuse cases. Molecular analysis results were obtained from official forensic laboratory reports. PIT was categorized as Day 0, Days 1–3, and Days 4–10. Post-incident actions, including bathing and clothing change, were recorded.

Results

DNA positivity was defined as the recovery of an interpretable male DNA profile, based on autosomal STR analysis and/or a reportable Y-STR haplotype, that was not attributable to the victim. Among cases, DNA positivity was detected in 20/136 (14.7%) with swab samples, in 54/68 (79.4%) with clothing submissions, and in 18/22 (81.8%) with crime-scene submissions. DNA positivity of the swabs was observed between 5 and 110 h post-incident, with the latest detection obtained from an internal anal (dry) swab. Bathing was associated with descriptively lower swab DNA detectability, whereas no statistically significant association was observed for clothing change.

Conclusions

Although DNA detectability decreases with increasing PIT, biological evidence—particularly from anogenital samples—may persist beyond the commonly applied 72-hour window. DNA positivity was more frequently observed in external anogenital swabs (vulvar and perianal) than in internal swabs (vaginal and anal). This finding should be examined with an extended sample size. Y-STR analysis enhanced detection in low-template or autosomal-negative cases, supporting comprehensive evidence collection regardless of PIT or post-incident actions.