A study in Virginia that utilized DNA testing suggests the rate of wrongful conviction for a crime is much higher than was previously thought.

John Roman of the Urban Institute, the lead author of the study, told the Associated Press there are likely "dozens, if not hundreds, of people who were convicted erroneously; dozens, if not hundreds, of people who were not convicted of a crime they committed who may have gone on to commit new crimes; and there were dozens, if not hundreds, of people who thought they had justice as a victim of a horrible crime who didn't."

The study, which was published Monday, analyzed the results of new DNA testing from 634 sexual assault and homicide cases that took place in Virginia between 1973 and 1987. DNA testing was not available at the time the crimes occurred, but the study was possible because a state forensic serologist -- who processed biological evidence in serious criminal cases -- had retained some physical evidence, such as cotton swabs and clothing swatches.

When these old pieces of evidence were subjected to DNA testing, 5 percent of those convicted were exonerated of the crime. When only sexual assault cases were considered, the number of those exonerated jumped even higher. DNA testing supported the exoneration of between 8 and 15 percent of those convicted of a sexual crime.

Previous research had put the rate of wrongful conviction around three percent. But a difference in methodology may explain the disparity between the two estimates.

"Usually, post-conviction DNA testing is performed only after extensive legal review with regard to the potentially probative value of the evidence," Roman and his colleagues explained in their study. "As a result, almost all instances of known wrongful convictions prior to this study were those detected after innocence was actively claimed."

"In contrast, this study identified potential wrongful convictions based on an unbiased sampling of violent crime convictions—the governor of Virginia ordered DNA testing on all eligible convictions, regardless of whether evidence pointed to the guilt or innocence of a convicted suspect."

Lemon told the Associated Press that the results from the Virginia study could most likely be applied to the rest of the nation.

"I think that states have a responsibility to take these findings seriously in other places and investigate other cases that they have where they have retained evidence, because chances are they're going to find far more wrongfully convicted people than they would have anticipated before this study."

[Man behind bars via val lawless / Shutterstock]