On October 31st, 1981, Johnny Frank Garrett was accused of both raping and murdering Sister Tadea Benz, a 76-year-old nun.
Garrett, then 17, had admitted guilt to the crime when examined by a forensic psychiatrist brought in by his defense team. During the interview the doctor said that she found him to have both severe brain damage as well as multiple personalities, only one of which confessed to the crime.
Garrett later stated that he did not confess anything and there were no tapes made of the interview.
His mother plead with the state of Texas to exonerate her son with the DNA evidence that they had. Texas has refused to do so to this day.
Johnny Frank Garrett was executed on February 11th 1992. He protested his innocence from the time of his conviction until his last words, which were, "I'd like to thank my family for loving me and taking care of me. And the rest of the world can kiss my everloving ass, because I'm innocent."
12 years later, cold case DNA testing found Leoncio Perez Rueda guilty of the rape and murder of Narnie Bryson, another elderly victim that was killed 4 months before Sister Benz.
Both cases had similar evidence, including white t shirts and curly brown hairs found on both scenes. Rueda confessed to the crime against Bryson and also confessed to killing a nun later. It was also caught on camera that Rueda stated that it was indeed his shirt found at the site of Sister Benz' murder. Source