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Sampling methods for the recovery of offender cellular material from victim skin surfaces

Harris, Tiana (2019) Sampling methods for the recovery of offender cellular material from victim skin surfaces. Masters by Coursework thesis, Murdoch University.

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Abstract

Sexual assault can cause major health and welfare issues and is considered a severe and inhuman criminal offence. During an assault, minute quantities of trace DNA can be transferred between a perpetrator, victim and/or crime scene. Transfer of DNA often occurs through strong physical skin-to-skin contact or oral acts resulting in saliva being deposited onto the skin of a victim. Understandably, the skin of a victim can be a critical scene for gathering biological material from the perpetrator to produce a DNA profile, so it is imperative that trace DNA evidence is correctly collected. This literature review aims to address the current research on sampling collection methods available and identify potential problems and factors influencing the recovery of DNA from skin-to-skin or saliva-to-skin contact.

Several factors have been identified to potentially influence the recovery of biological material from skin, including, but not limited to, the effect of background DNA and shedder status. Whether or not an individual consistently deposits the same amount of DNA every time, particularly after washing hands, is still an area of constant debate. Nevertheless, background DNA has been found to impact the conclusiveness of a profile, and while it is unavoidable, a sampling method that collects the least quantity of background DNA would be extremely beneficial. There are several sample collection methods available including the single swab, double swab, tape-lift and mini-tape. Unfortunately, the use of adhesive tapes is more common for the recovery of cellular material from textiles, with little research focusing on skin as a target surface. Presently, the double swabbing method is considered the gold standard technique for sampling skin, with numerous studies utilising this procedure. While the idea behind this technique is promising, the support for this method was found to be far from universal. There is a lack of overwhelming support for any single sample collection technique, therefore a new method could be introduced using alcohol wipes. Not only are alcohol wipes pre-moistened making for a faster application, but they are also cheap and easily accessible to medical and healthcare workers. There is a need for a single study to compare all the available and potential collection methods, focusing specifically on the recovery of offender DNA from victim skin.

Item Type: Thesis (Masters by Coursework)
Murdoch Affiliation: School of Veterinary and Life Sciences
United Nations SDGs: Goal 16: Peace, Justice and Strong Institutions
Supervisor(s): Chapman, Brendan and Kelly, M.
URI: http://researchrepository.murdoch.edu.au/id/eprint/46959
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