Lawyers, Scientists Try to Unravel Thorny New DNA Standard
DALLAS — Texas prosecutors left a meeting Friday without the precise roadmap they were looking for when it comes to navigating the more conservative DNA standards used by crime labs in Texas and nationwide.
But they didn't leave the Southwestern Institute of Forensic Sciences empty-handed, they said.
“It would have been nice to see more answers," Inger Chandler, chief of the conviction integrity unit in the Harris County district attorney's office. "As lawyers, we tend to see things in black and white, and we're learning there's a lot of gray."
Chandler was one of many prosecutors who attended a Texas Forensic Science Commission meeting on how past and future cases could be affected by a new standard in analyzing data involving "mixed DNA." That type of DNA refers to when more than one person's DNA is found on evidence.
While there's no proof that the new standard — adopted by the Texas Department of Public Safety crime labs and other labs used by DA's offices — would exclude a defendant, the new protocol could reduce the likelihood that an individual's DNA is the only source of genetic material left at a crime scene.
About 50 attorneys, prosecutors, defense attorneys and lab technicians from across the state attended Friday’s meeting. In a few hours, experts tried to temper the expectations about DNA testing that were built over more than a decade.
"One of the problems was DNA was called the gold standard," Bruce Budowle, director of the University of Texas Health Science Center's Institute of Applied Genetics, said. "Big mistake."
DNA analysis provides answers, but there has to be rigorous interpretation of DNA results, the experts said.
Crime labs have recently adopted the new “mixed DNA” standard. The DPS switched to it on Aug. 10. The move has prompted prosecutors like Chandler to resend evidence in pending cases to the lab to have the data analyzed using the new standard. In Houston's Harris County, that's about 500 pending cases where DNA evidence will be introduced at trial.
In addition, DAs are notifying defendants who are already convicted about the new standard. For example, Harris County prosecutors have already notified those convicted of capital murder and awaiting execution. It is not known how many of the 253 inmates on Texas’ death row were convicted with mixed DNA. Of the 253 inmates on Texas death row, 90 are from Harris County.
Not every criminal case involves DNA evidence, and fewer still involve evidence where multiple sets of DNA are recovered from a single piece of evidence, like a doorknob.
But since 2008, there's been a "skyrocketing of touch evidence" leading to a sort of "swabathon" trend, according to John M. Butler, one of four DNA typing experts called by the Forensic Science Commission to Dallas on Friday to answer questions.
A week ago, DPS sent Texas prosecutors a log of more than 24,000 lab tests since 1999 to help them determine if older cases should be re-evaluated.
For now, experts say it’s still hard to answer what the new standard will mean in a courtroom.
"We really can't say what the impact will be," Budowle said of the new standards.
The issue is expected to be addressed again at the Forensic Science Commission's next meeting in October.