From the Houston Chronicle, by Gabrielle Banks, January 30, 2016 Updated: February 1, 2016 11:21am:
Texas criminal justice organizations have begun reviewing thousands of cases that relied on an outdated method for calculating the odds that a particular person left DNA evidence at a crime scene.
At issue are samples that include more than one person's DNA, such as evidence swabbed from a countertop after a convenience store heist or taken from bodily fluids in a rape kit. Experts revised national guidelines for calculating odds in these scenarios six years ago, but no one sounded an alarm or asked prosecutors to re-examine cases that used the previous methodology.
The science behind DNA testing hasn't changed, but for mixed samples, analysts now focus on fewer factors in their results before determining the odds of someone being at the scene. The findings are more conservative.
Inaccurate calculations still might be happening around the country, said Barry Scheck, director of the Innocence Project, a legal nonprofit that has reviewed post-conviction DNA evidence since 1992. Scheck took an informal poll last week among forensic scientists at a national conference on the outdated "multiple contributor" DNA protocol, and all agreed: "Texas is the only place that's systematically trying to correct it."
The review was initiated by crime labs and coordinated by the state's Forensic Science Commission. Prosecutors, defense lawyers and judges have joined the effort to comb through old cases, contact affected parties and, in some instances, halt the judicial process to ensure the science is up to date.
Photo Credit: Steve Gonzales, Houston Chronicle