08.27.08
New Method for Processing Rape Kit Evidence
In today’s show, adapted from an article written by Fariss Samarrai, senior news officer for UVa’s Office of Public Affairs, we discuss the research of Jessica Voorhees Norris, a Ph.D. candidate in forensic chemistry at UVa, who has developed a method for handling rape kit evidence that reduces part of the DNA analysis time from 24 hours to as little as 30 to 45 minutes.
With approximately 250,000 items of sexual assault evidence mired in three- to 12-month backlogs as they await analysis in U.S. forensic laboratories, there is an alarming nationwide need for a time-efficient way to get this work done. And according to Jessica Voorhees Norris, a Ph.D. candidate in forensic chemistry, she has found a better way. She developed a method for handling rape kit evidence that reduces part of the DNA analysis time from 24 hours to as little as 30 to 45 minutes and improves the sperm cell recovery rate by 100 percent. If her method is adopted by forensic labs – and the results accepted by courts – the backlog could potentially be reduced within months.
Norris, who conducted her research in the lab of UVa chemistry professor James Landers, long ago realized that new methodologies would be needed to keep up with the growing accumulation of unanalyzed samples. She devoted her doctoral research to developing more effective and time-efficient methods.
Norris said, “There is an overwhelming demand for DNA analysis of sexual assault evidence, but laboratories have neither the funding nor the manpower to handle the caseload in a timely manner. Juries have come to expect DNA evidence in sexual assault cases, but forensic labs are not able to perform in a timely and efficient manner due to limitations in the currently used technologies.”
When a woman is sexually assaulted and comes forward to the police, a sample is taken and then sent to a forensic lab. In high-profile cases, the analysis is usually performed immediately, though overnight incubation is required to achieve a result. In most routine cases, though, the sample is put into storage, sometimes for as long as a year, before it finally reaches its turn in the cycle to be analyzed or when the case approaches a court date. The sample may degrade during the waiting period, resulting in a compromised finding.
Lab technicians must perform a number of steps to get their results. First, female and male cells must be removed from the swab with a special detergent. DNA from the vast number of epithelial cells from the victim must be separated from the far fewer sperm cells from the perpetrator. To do this, cells must sit overnight in an enzyme that bursts open the relatively fragile female cells to release their DNA for analysis. After the female DNA is removed, the highly durable sperm cells are burst open using stronger reagents.
Once the DNA is extracted, profiles, in effect, are generated for both the victim and the attacker. It is a time-consuming process, one that has been in use for more than two decades. Norris’ method streamlines the method for separating the male and female DNA fractions, eliminating the need for the overnight incubation while doubling the recovery of sperm cells.
Norris said, “This new process works extraordinarily well and could be implemented in forensic labs today. Unfortunately, getting labs to adopt a new protocol and getting legal systems to accept a new technology may take several years. In the meantime, the backlog of unanalyzed samples will continue to grow.”
Norris noted that forensic science is not simply about proving guilt. She said, “Forensic science is about finding the truth in a timely manner. It is about using science to identify the guilty and exonerate the innocent.”
You’ve been listening to the Oscar Show, I’m Jacob Canon. Join us for our next show, when we discuss the research of Ron Williams, a professor of electrical and computer engineering, and his teams research of how to make more intelligent climate control systems, to aid in energy efficiency.