Optimization of Spermatozoa Capture During the Differential Extraction Process for STR Typing with the Potential for Automation

Marshall, Pamela. Optimization of Spermatozoa Capture During the Differential Extraction Process for STR Typing With the Potential for Automation. Master of Science (Forensic Genetics). May, 2002. In 1998, within the United States, it is estimated that a rape occurred every 2.3 minutes. In 1995, according to the Bureau of Justice Statistics, an estimated 350,000 rapes or sexual assaults (R/SA0 were experienced by persons age 12 or older. Of the estimated 100,000 R/SA reported, there were only approximately, 25,000 cases analyzed by crime labs nationwide. The majority of crime laboratories throughout the U.S., especially those in major metropolitan cities, have a significant backlog of unresolved R/SA cases. With the implementation of the Convicted Offender Database (CODIS), it is essential that all R/SA cases by analyzed, especially those lacking a known suspect. The comparison of the short tandem repeat (STR) profiles derived from sperm DNA recovered from evidentiary material with CODIS samples would provide the police with critical investigative leads resulting in the identification of the assailant. The goal of this research is to develop a cellular sorting method for the isolation of sperm cells from sexual assault samples which will: 1) take advantage of differentiating features (extracellular antigenic sites) for complete separation of cell types, 2) provide a more efficient means of sperm recovery, increasing DNA yield from the male fraction, and 3) ensure the DNA isolation process is compatible with the amplification of the CODIS core STR loci. Overall, the proposed technique will increase the probability of success in the analysis of sexual assault case samples. (NIJGrant #: 2000-IJ-CX-K009).