Crime Labs Struggle with Flood of DNA Samples

December 12, 2007

by Ari Shapiro, NPR

Forensic DNA databanks have grown steadily in the last 20 years across the country. The first databases only included samples from convicted felons. Now some states and cities are taking DNA samples from arrestees and those convicted of misdemeanors. Although some studies have shown that larger databases correlate with greater numbers of DNA matches from crime scenes, there are also drawbacks to expanding a DNA database.

"What happens is you create an immediate backlog," says DNA consultant Chris Asplen.

Backlogs of DNA crime scene evidence are a significant concern across the country. The Los Angeles Times recently reported that the L.A. Police Department has nearly 7,000 untested DNA samples from sexual assault cases in cold storage. A state audit said the LAPD would need more than $9 million to clear the backlog.

During the time that samples remain untested in cold storage, offenders may commit crimes that could have been prevented.

Dr. Paul Ferrara, who created the first DNA database in 1989 as head of Virginia's Department of Forensic Science, remembers one rape case from the 1990s. It took the lab months to realize that the crime scene DNA matched someone whose profile was in the database. "In the meantime," Ferrara says, "this guy had raped and murdered a woman by the name of Gemma Saunders."

It is far easier and less expensive to run known offender samples than it is to run crime scene samples.

"You can run thousands of felon samples for every couple cases of crime scene evidence you run," Ferrara says.

With a major DNA database expansion, a forensics department with a limited budget suddenly has to balance an existing backlog of crime scene samples with tens of thousands of known offenders who have to be added to the database right away.

Civil libertarians also have concerns about expanding databases. Law-enforcement groups like to say that giving police a DNA sample is no different from giving police your fingerprint, but Tania Simoncelli of the ACLU says DNA is far more personal than a fingerprint. A DNA sample "contains a great deal of information. It could be about susceptibility to disease, as well as your family history," Simoncelli says. "This is private, personal information about you that goes far beyond just your identification."

Forensics labs could take one step that would make civil libertarians very happy. Right now, labs hold actual biological samples from known offenders. Privacy advocates want the labs to throw out the full DNA sample and retain just the 13 loci — the points that scientists use to match a known sample to a crime scene. That way, scientists couldn't search for illnesses or other private information.

Tony Rauckauckus, the district attorney for Orange County, Calif., considered discarding his county's biological DNA samples and decided against it.

"There's a possibility that it might have to be tested again," Rauckauckus says.

His county recently decided to require DNA samples from anyone who pleads guilty to a misdemeanor. So far, Rauckauckus hasn't received any complaints.

"I just think the more people we have in the database, the more likely it is that we're going to be able to catch people who commit more serious crimes," he says.