The national backlog in sexual assault cases is estimated to be between a hundred thousand and a half million untested rape kits. Current methods of analysis are time and labor intensive, requiring overnight procedures and delivering a success rate lower than 40%.
The primary challenge crime labs face in analyzing these cases is the separation of purified male DNA from the mixture of primarily female DNA from gynecological swabs. Effective elution of the sample from the swab and efficient separation of intact sperm cells from epithelial and other cellular debris allow for a successful polymerase chain reaction amplification and short tandem repeat (STR) analysis of the perpetrator DNA. Capillary zone electrophoresis (CZE) is a promising tool to perform the cell separation and has three major advantages over alternative technologies: small amount of sample is consumed, which allows for replicate analyses of limited available evidence; rapid separation time compared to standard methods; and single cell detection and collection when interfaced with an automated fraction collector that the researcher has helped develop. Preliminary results have shown the migration of sperm cells in a confined band in under 15 minutes. In addition, CZE instruments are presently used in the majority of crime laboratories for DNA analysis, so analysts will already have the necessarily training to operate this CZE-based technology.
The study will be divided into three phases and conducted over 36 months: 1) Develop a CZE system utilizing laser detection to determine and optimize the migration time of sperm in post-coital samples collected by Dr. Ashley Hall (University of Illinois at Chicago); 2) Develop CZE-Fraction Collection parameters to separate and collect purified sperm cells; 3) Analyze STR profiles of samples of various conditions tested up to one year following collection.
Conditions imitate storage of current rape kits at room temperature, 4°C, and -20°C. This work will result in a patentable technology that can be implemented in crime labs in the US, a doctoral dissertation, at least two publications in high impact journals, and presentations of results at national and international scientific meetings.
ca/ncf
