DALLAS — Prosecutors declared a Texas man innocent of a rape and robbery that put him in prison for 30 years, more than any other DNA exoneree in Texas.

DNA test results that came back barely a week after Cornelius Dupree Jr. was paroled in July excluded him as the person who attacked a Dallas woman in 1979, prosecutors said Monday. Dupree was just 20 when he was sentenced to 75 years in prison in 1980.

Now 51, he has spent more time wrongly imprisoned than any DNA exoneree in Texas, which has freed 41 wrongly convicted inmates through DNA since 2001 — more than any other state.

"Our Conviction Integrity Unit thoroughly reinvestigated this case, tested the biological evidence and based on the results, concluded Cornelius Dupree did not commit this crime," Dallas County District Attorney Craig Watkins said.

Dupree is expected to have his aggravated robbery with a deadly weapon conviction overturned Tuesday at an exoneration hearing in a Dallas court.

There have been 21 DNA exonerations in Dallas since 2001, more than any other county in the nation. Only two states — Illinois and New York — have freed more of the wrongly convicted through DNA evidence than Dallas, according to the Innocence Project, a New York-based legal center representing Dupree that specializes in wrongful conviction cases.

Dallas’ record of DNA exonerations is unmatched nationally because the county crime lab maintains biological evidence even decades after a conviction, leaving samples available to test. In addition, Watkins has cooperated with innocence groups in reviewing hundreds of requests by inmates for DNA testing. Watkins, the first black district attorney in Texas history, has also pointed to what he calls "a convict-at-all-costs mentality" that he says permeated the DA’s office before he arrived in 2007.

Dupree’s 30 years in prison will surpass James Woodard, who spent more than 27 years in a Texas prison for a murder that he was cleared of in 2008.

Nationally, there are at least two other DNA exonerees who spent more time in prison, according to the Innocence Project. James Bain was wrongly imprisoned for 35 years in Florida and Lawrence McKinney spent more than 31 years in a Tennessee prison. Phillip Bivens was locked up for more than 30 years in Mississippi, but it wasn’t immediately clear whether he or Dupree were in longer.

The DNA testing in Dupree’s case also excluded a second defendant, Anthony Massingill, who was subsequently convicted in another sexual assault case and sentenced to life in prison. Massingill remains in prison but maintains his innocence. DNA testing in that second case is ongoing.

Dupree was charged in 1979 with raping and robbing a 26-year-old woman and sentenced in 1980 to 75 years in prison for aggravated robbery. He was never tried on the rape charge.

According to court documents, the woman and her male companion stopped at a Dallas liquor store in November 1979 to buy cigarettes and use a payphone. As they returned to their car, two men, at least one of whom was armed, forced their way into the vehicle and ordered them to drive. They also demanded money from the two victims.

The men eventually ordered the car to the side of the road and forced the male driver out of the car. The woman attempted to flee but was pulled back inside.

The perpetrators drove the woman to a nearby park, where they raped her at gunpoint. They debated killing her but eventually let her live, keeping her rabbit-fur coat and her driver’s license and warning her they would kill her if she reported the assault to police. The victim ran to the nearest highway and collapsed unconscious by the side of the road, where she was discovered.

About five days later, two men whose descriptions did not match Dupree tried to sell the rabbit-fur coat at a grocery store two miles (three kilometers) from the liquor store, according to court documents. The car stolen from the victims was found abandoned in the parking lot.

Dupree and Massingill were arrested in December because they looked similar to two suspects being sought in another sexual assault and robbery. The 26-year-old woman picked both men out of a photo array, but her male companion did not identify either defendant in the same photo array.

Dupree was convicted and spent the next three decades appealing. The Court of Criminal Appeals turned him down three times.

The Innocence Project, which took on his case in 2006, obtained DNA testing last summer on biological evidence taken from a vaginal swab. In July, shortly after Dupree’s release, the test results cleared Dupree and Massingill.

The hearing is happening now because authorities needed additional testing to confirm that the 30-year-old biological material was a DNA match to the victim.