Sexual assault investigations utilize both physical and biological evidence to aid in the investigation. Physical evidence may include fingerprints, hair, fibers, stains, soil, and glass. Biological evidence may include semen, saliva, vaginal secretions, menstrual blood, and skin. Semen, often found in small or trace quantities, is of great importance when trying to identify the perpetrator. From the semen sample, DNA profiles using autosomal short tandem repeats (aSTRs) (gold standard in forensic science) or Y-chromosome short tandem repeats (Y-STRs) can be obtained and can be used to identify a perpetrator through comparison to suspect reference samples or by searching the profile against a DNA database (CODIS). Obtaining DNA profiles can be challenging when assaults are reported many days after the incident. The amount of semen will decrease as the time frame increases due to various factors such as drainage from the vagina. To potentially overcome this obstacle and improve the recovery of profiles from extended interval samples, it may be possible to develop novel collection and analysis methods using individual or few sperm cells. Small quantities of sperm cells may still be present in extended interval samples that may otherwise fail to provide a DNA profile using conventional methods. The work presented here focuses on the development of these novel analysis methods using micromanipulation techniques and enhanced amplification strategies for the analysis of individual sperm cells to determine if a full DNA profile is present. The developed methods will be applied to the analysis of extended interval post coital samples.
Bachelor of Science (B.S.)
College of Medicine
Penn, Amanda, "Micromanipulation and Genetic Analysis of Individual Sperm Cells for Sexual Assault Investigations" (2019). Honors Undergraduate Theses. 522.