Effectiveness of a novel extraction method for semen: comparison using liquid samples and dried stains
Cassis, Patricia Rose
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Forensic analysis of deoxyribonucleic acid (DNA) collected from sexual assault evidence is a multi-step process that requires a great amount of time and resources. A large percentage of samples are mixtures containing DNA from a major female contributor and at least one minor male contributor. The amount of male DNA present is often much less than that of the female, making it difficult to achieve a full short-tandem repeat (STR) profile for identification purposes. The current method employed by many forensic laboratories to separate sperm DNA from non-sperm DNA is the differential extraction. Although a robust and reliable method when applied to liquid samples, the procedure has failed to evolve significantly since first developed.1,2 Between the time it has been collected and tested, sexual assault evidence becomes dried and aged, contributing to the potential loss and degradation of already low amounts of DNA and increasing the likelihood of an incomplete profile.2 This study tests the effectiveness of a combination of enzymes to release DNA from sperm using a variety of substrates. Although this method extracted greater amounts of male DNA than the traditional Qiagen® extraction, further research is necessary to determine if the application of this new method can improve or eventually replace the current procedures.