This study analyzed the results of new DNA testing of old physical evidence from 634 sexual assault and homicide cases that took place in Virginia between 1973 and 1987 in the first study of the effects of DNA testing on wrongful conviction in a large and approximately random sample of serious crime convictions. The study found that in five percent of homicide and sexual assault cases DNA testing eliminated the convicted offender as the source of incriminating physical evidence. When sexual assault convictions were isolated, DNA testing eliminated between 8 and 15 percent of convicted offenders and supported exoneration. Past estimates generally put the rate of wrongful conviction at or less than three percent.