A man convicted of raping a woman in 1981 and sentenced to life in prison has been cleared by DNA evidence and will be released, according to attorneys who have helped free 14 other wrongfully convicted inmates in Dallas County.

Charles Chatman, 47, is expected to be released Thursday after spending more than 26 years behind bars, said Natalie Roetzel of the Innocence Project of Texas.

"I never lost hope," Chatman told The Associated Press. "I always believed I would get out. I didn't know when or how, but I kept believing."

Chatman would be the 15th inmate convicted in Dallas County and later exonerated by DNA evidence, the most of any prosecuting office in the nation, according to the Innocence Project.

"Charles has always maintained his innocence," said Michelle Moore, a Dallas County public defender.

Since 2001, DNA tests have exonerated at least 30 wrongfully convicted inmates in Texas, the most of any state, according to the Innocence Project, a New York-based legal clinic that seeks to uncover wrongful convictions.

Jamille Bradfield, a spokeswoman for the Dallas County District Attorney's Office, confirmed that there will be a court hearing Thursday morning at which Chatman is expected to win his release.

Chatman was 20 when the victim, a young woman in her 20s, picked him from a photo lineup, Moore said. His nearly 27 years in prison for aggravated sexual assault will make him the longest-serving inmate in Texas to be freed by DNA evidence, she said.

Chatman said he was already in jail on an unrelated burglary when he was charged. He said he lived five houses down from the victim for 13 years but never knew her. At the time the woman was assaulted, Chatman said he didn't have any front teeth; he had been certain that feature would set him apart from the real assailant.

Moore said Chatman applied for DNA testing in 2004 but was told the process could be risky. The only evidence containing DNA was from a swab from the victim, Moore said, and a single test would consume the entire sample. An inconclusive test would exhaust all evidence.

Despite the risks, Chatman reapplied for testing early last year.

"This is a guy who's had to face horrible decisions," Moore said.

Dallas County District Attorney Craig Watkins has started a program in which law students, supervised by the Innocence Project, are reviewing about 450 cases in which convicts have requested DNA testing to prove their innocence.