The Texas Forensic Science Commission is implementing more conservative standards in DNA testing where there is “mixed DNA.” Some pieces of evidence, such as doorknobs, might have multiple subjects’ DNA on them. The new standards will use new statistical data released by the FBI based on population statistics.
“It still included the defendant,” Roady said of the new analysis this past summer in a case. “However, the likelihood that the defendant was the only source of the DNA went from 1 in a billion, down to less than 1 in a 100.”
The Commission is reviewing cases from the last decade, and potentially thousands of cases could be re-tried as a result.