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Abstract

As the capabilities of DNA analysis within forensic science has evolved, so has a need to research into how DNA transfers and persists on various surfaces and under difference conditions. Research into this area not only allows for forensic processes and procedures to be optimized in order to increase the success of extracting DNA from exhibits, but also aids in strengthening the interpretation of DNA evidence for admissibility in court. An area where this is particularly relevant is within sexual assault investigation, which often relies on the ability to locate and recover DNA from semen deposited during the offence to assist in building a successful case for prosecution. Whilst intimate swabs are routinely used in forensic examinations to collect traces of DNA, they are time sensitive due to the increasing degradation of DNA after deposition, and therefore may not be suitable in some contexts. Therefore, it may be appropriate to recover DNA from other sources, such as clothing worn by the victim, and as such, this research sought to identify if spermatozoa could still be identified on cotton underwear after laundering repeatedly at both 30ºC and 60ºC. The results show that spermatozoa persisted on cotton underwear laundered five times, regardless of temperature, although lower quantities of spermatozoa were recovered from the 60ºC wash cycles. Additionally, the effectiveness of using alternate light sources to identify semen stains on cotton was significantly reduced after laundering. Overall, the findings provide evidence that clothing worn by the victim of a sexual assault may still be suitable for DNA analysis despite repeated laundering, and that spermatozoa can still be present even if exhibits return a negative presumptive reaction.

Course: Criminology and Forensic Studies - BSc (Hons) - C2039F

Date Deposited: 2022-08-08

URI/permalink: https://library.port.ac.uk/dissert/dis13958.html