Independent DNA testing has found two men to have been wrongly convicted of sexual assault, raising to five the number of people exonerated because of forensic evidence saved by a meticulous scientist, Gov. Mark R. Warner said Wednesday.

The two men, who have requested that their names not be released, had already completed their prison sentences, Warner said in a news release. He did not say what errors were made in their convictions.

Prosecutors in Norfolk and Alexandria, where the cases were investigated, have asked the governor to grant absolute pardons to both men. Warner said the men's petitions will go through the normal review process.

Three other men who were convicted of rape were cleared thanks to samples saved by the late state forensic scientist Mary Jane Burton.

As a result of those exonerations, Warner ordered an independent lab to review a random sampling of cases she handled to see if others had been wrongly convicted. Now all samples saved by Burton will be reviewed, the governor said.

Burton, who died in 1999, worked in the Virginia state crime lab from 1974 to 1988.

Even before DNA testing had been invented, she had taken tiny bits of evidence she tested — cotton swabs and clothing fragments smeared with blood, semen and saliva — and inserted them into case files, which eventually landed in a storage facility.

Few people knew of Burton's habit and the samples were forgotten until 2001, when Paul Ferrara, director of the state Department of Forensic Science, discovered a case file that contained an old cotton swab.

Marvin Anderson, Arthur Lee Whitfield and Julius Ruffin, who were all wrongfully convicted of separate rapes in the 1980s, were cleared after Burton's samples were found and DNA testing revealed they were not the rapists. They served a combined 59 years behind bars.

At the request of Warner, private lab Bode Technology Group in Springfield then tested nearly 300 samples saved by Burton in 31 cases, leading to the latest exonerations.

In the Norfolk case, the man was convicted based on identification from the victim, who is now deceased, Norfolk Commonwealth's Attorney Jack Doyle said.

The review of the Alexandria case resulted in a "cold hit" in Virginia's DNA data bank, Warner said in the release. Because of that, Alexandria Commonwealth's Attorney Randolph Sengel said he couldn't comment on the case because it is now an open investigation.

As many as 300 more cases may be reopened, Ferrara said in the written statement released by the governor.

Warner applauded the Department of Forensic Science.

"The powerful crime-fighting tool of DNA has helped add certainty to our justice system for many years now," he said. "I believe a look back at these retained case files is the only morally acceptable course, and what truth they can bring only bolsters confidence in our system."

Peter Neufeld, co-founder of the legal-aid group the Innocence Project, praised Warner for expanding the review.

"There is little doubt that once they expand this audit ... many other Virginians will be walking out of prison innocent men," Neufeld said.