Contribution to the Development of Guidelines in the Analysis of Biological Evidence in Sexual Assault Investigations

• Published in: Journal of forensic sciences Vol. 64; no. 2; pp. 534 - 538
• Main Authors: Ferreira‐Silva, Benedita, Porto, Maria João, Magalhães, Teresa, Cainé, Laura
• Format: Journal Article
• Language: English
• Published: United States Wiley Subscription Services, Inc 01-03-2019
• Subjects: Collection; collection methods; Criminal investigations; Deoxyribonucleic acid; DNA; DNA typing; double swab technique; Elution; forensic genetics; forensic science; Forensic sciences; Guidelines; nylon swab; Sampling methods; Sex crimes; sexual assault; swab with desiccator; swab with desiccator; nylon swab; sexual assault; double swab technique; forensic genetics; forensic science; collection methods; DNA typing
• ISSN: 0022-1198; 1556-4029
• DOI: 10.1111/1556-4029.13879

This investigation intends to study materials and techniques used for biological evidence collection in sexual assault cases and is divided into two stages: in stage one, methods for biological evidence collection (the single swab (including three variants) and the “double swab technique”) were compared; in stage two, swabs’ component material was compared. The sampling was composed of 42 heterosexual couples who provided mock samples. The collection methods in which the whole swab is covered by evidence presented significantly better outcomes (p < 0.001), such as the “double swab technique.” Additionally, nylon swabs proved to present significantly better features regarding the capacity of sample elution, providing significantly higher amounts of DNA (p ≤ 0.034). This study provides guidelines for better collection of biological evidence regarding the collection method using a swab and the proper swab material to utilize.