AUSTIN (KXAN) — DNA evidence can be the key for prosecutors as they try to convince a jury of a suspect’s guilt. Now, lawyers are reopening what could be thousands of case files to see if DNA results will need reevaluation.

Legal experts tell KXAN a change in scientific standards is prompting the unprecedented statewide analysis. However, the issue is not with the actual testing of what are called DNA mixtures, but rather, with the probabilities scientists generate and prosecutors often use as evidence of the degree of the tests’ conclusiveness.

“I think the science evolved in the area of how to calculate the frequency that certain DNA profiles appear at random in the population,” said Bob Wicoff, director of the Texas DNA Mixture Review Project. “So, these deal with cases where the evidence from a crime scene contains two or more persons DNA profiles in that evidence.”

Wicoff is also the Chief of the Appellate Division of the Harris County Public Defender’s Office. Right now, his job is sorting through cases to find out if any qualify for a reevaluation because of the DNA mixture issues. The Texas Indigent Defense Commission is funding the project.

“It’s much larger than anything I’ve seen in this state or any other state,” said Wicoff. “Texas is very proactive about trying to find and correct forensic problems.”

He says since March, the project has received about 750 cases. Of those, about 30 have gone on for reevaluation, he said. Still, he believes the amount of cases where someone could potentially seek a review could number in the tens of thousands. Then lawyers will need to see how big of a role DNA evidence played in each case and if they will need to have the DNA reexamined.

It is still unclear exactly what the outcome of the cases will be. The state began tackling the DNA issues last year. Wicoff believes there could be years left before attorneys comb through all the cases that could be subject to a second analysis. So far, he says reanalysis more often provides a probability that would not help the defense’s case. However, Wicoff says there was at least one example where the reexamination returned much different results in a defendant’s favor.

“Upon retesting they couldn’t even match that person to the DNA; it was rendered inconclusive,” said Wicoff. “So, that’s a big change in the direction favoring the defendant.”

“We first have to get through cases with the mixtures. Determine which ones have mixtures. Determine who wants it to be reanalyzed and then look at the other factors in the case,” said Robert Kepple, Executive Director of the Texas District & County Attorneys Association. “I think there’s a lot of lawyers looking at those cases to determine whether or not there was mixture evidence and whether or not, really it would make any difference to reanalyze that case.

Kepple said prosecutors are spending a “tremendous” amount of time looking at cases to see if the DNA mixture evidence made a difference in cases.

“There are probably very, very few cases that have new evidence that will somehow cast doubt on the guilt in that particular case,” said Kepple.