Sexual assault specimens: what happens in the lab?

Abstract

Examination of exhibits taken from a patient of a suspected sexual assault for the presence of biological material has undergone massive change over the last few years. The presence of semen on one of the exhibits will invariably result in a DNA profile but even when semen is absent, trace DNA analysis can provide sufficient information to identify the alleged offender. With this increased sensitivity comes the increased likelihood of contamination, and protocols must be present to ensure that contamination is minimised. Nevertheless, while the correct result is an imperative, the criminal justice system must also be served by reducing the backlog of unexamined sexual assault kits and providing quick feedback of the results to the criminal investigator. This talk will discuss the success of newer methodologies available in the NSW DNA testing laboratory including the use of new extraction chemistries and liquid handling platforms which has resulted in higher throughput of samples. Using case examples it will examine the use of alternative methodologies such as Y-STR DNA kits in providing evidence to the courts. Lastly, it will address the increased sensitivity of detection and issues relating to contamination minimisation at a laboratory level. Examination of exhibits taken from a patient of a suspected sexual assault for the presence of biological material has undergone massive change over the last few years. The presence of semen on one of the exhibits will invariably result in a DNA profile but even when semen is absent, trace DNA analysis can provide sufficient information to identify the alleged offender. With this increased sensitivity comes the increased likelihood of contamination, and protocols must be present to ensure that contamination is minimised. Nevertheless, while the correct result is an imperative, the criminal justice system must also be served by reducing the backlog of unexamined sexual assault kits and providing quick feedback of the results to the criminal investigator. This talk will discuss the success of newer methodologies available in the NSW DNA testing laboratory including the use of new extraction chemistries and liquid handling platforms which has resulted in higher throughput of samples. Using case examples it will examine the use of alternative methodologies such as Y-STR DNA kits in providing evidence to the courts. Lastly, it will address the increased sensitivity of detection and issues relating to contamination minimisation at a laboratory level.