Wearer and non-wearer DNA on the collars and cuffs of upper garments of worn clothing

Abstract

During an investigation, the question of interest might be whether or not a person has worn a given garment. Wearer DNA studies have contributed to our knowledge and understanding of DNA transfer and persistence on items of worn clothing. However, there is currently no extensive dataset on DNA profiling outcomes from a variety of upper garments. Therefore we investigated the DNA profiling outcomes from the collars and/or cuffs of forty-four upper garments of worn clothing and determined the quantity of wearer and non-wearer DNA recovered. Interpretable DNA profiles were more likely to be obtained from collars than cuffs (84% versus 71%). The wearer was detected in all interpretable profiles and a major profile corresponding to the wearer was the most common outcome from both collar and cuff samples (48% and 50%, respectively). There was large variation in the amount of wearer DNA recovered and the average recovered was approximately 20 ng. Usually more wearer DNA was found on collars than cuffs of the same garment and, on average, more non-wearer DNA was found on cuffs than collars. No DNA was recovered from the cuffs of two garments despite these garments being worn for three and four hours, respectively. On one occasion a non-wearer contributed more DNA to a cuff sample than the wearer. We found no correlation between wearing time and the amount of wearer DNA recovered which indicates that other factors (e.g. shedder status and/or the manner of contact between the garment and skin) have a greater influence, than wearing time, on the amount of DNA transferred. However, there was a positive correlation between wearing time and the likelihood of obtaining interpretable profiles. This work has generated data to support the evaluation of DNA evidence from clothing and we provide a case example to demonstrate this.

Keywords: Activity level propositions; DNA transfer; Evaluative reporting; Forensic; Wearer DNA.