Touch DNA analysis remains a challenging area in forensic genetics, as numerous factors may influence both the quality and quantity of DNA deposited at a crime scene through object handling. Likewise, DNA can be transferred to a victim’s body following hand contact or touching. In this study, we investigated whether male DNA can be detected on female hair following a direct hair-pulling event.

To this aim, we investigated the genetic background on hair samples from female participants (n = 10) collected at different time spans after the last hair washing (up to 72 hours), for a total of 37 tests. Afterwards, seven simulated hair pulling events on synthetic hair, with 5- and 10-second pulling durations, were set up (two male participants were enrolled for these tests). 

During all tests, a lock of hair (approximately 15 mm in diameter) was double swabbed for 15 seconds, extracted using the Maxwell® FSC DNA IQ™ Casework Kit (Promega), quantified with PowerQuant® (Promega), and typed with PowerPlex® ESI/ESX and/or PowerPlex® Y 23 (Promega) kits.

The data show that full autosomal female profiles could generally be obtained from the genetic background of the hair-lock surface, with traces of male contamination detected in 51.3% of the cases (likely due to contributions form cohabiting partners or family members). From all seven hair pulled DNA samples, full or partial Y specific profiles were obtained. This finding supports the potential of hair swabbing procedures to provide useful information for the genetic identification of an assailant.

At the time of this abstract, additional simulations are in progress on female participants to assess the persistence of male DNA on female hair. In addition, the influence of pulling duration and the shedder status of male participants are under investigation.

Authors

• Barbara Di Stefano (Department of Medicine, Surgery and Health, University of Trieste, Italy)
• Pierangela Grignani (Department of Public Health, Experimental and Forensic Medicine, Section of Legal Medicine and Forensic Sciences, University of Pavia, Italy)
• Solange Sorçaburu Ciglieri (Department of Medicine, Surgery and Health, University of Trieste, Italy)
• Barbara Bertoglio (Department of Public Health, Experimental and Forensic Medicine, Section of Legal Medicine and Forensic Sciences, University of Pavia, Italy)
• Carlo Previderè (Department of Public Health, Experimental and Forensic Medicine, Section of Legal Medicine and Forensic Sciences, University of Pavia, Italy)
• Paolo Fattorini (Department of Medicine, Surgery and Health, University of Trieste, Italy)