AUSTIN (KXAN) — The Travis County District Attorney's Office said Wednesday a man who has been incarcerated for decades should be granted a new trial and should be released from prison as he waits to hear a decision from the Texas Criminal Court of Appeals. Alvin Stewart was convicted 20 years ago of killing his former teacher and then robbing him of a VCR, according to the DA's office. In the trial, the state alleged Stewart "was in a voluntary sexual relationship" with his seventh-grade music teacher, which is why he was there the night of the murder, the release said. Stewart was convicted of manslaughter and robbery and was sentenced to 20 years for manslaughter and 60 years for robbery. This year, several witnesses, including prosecutors, the defense attorney, students and colleagues, were called to testify about the "nature of the relationship" between Stewart and the teacher, which included "that it may have been sexual in nature and started as early as middle school," the release said. The defendant testified on the final day of the in-person hearings, the release said. "The agreed-upon Findings of Fact and Conclusions of Law find that the original defense attorney was ineffective for failing to investigate the nature of the relationship. Had an investigation been done, the defense would have been able to present to the jury evidence of grooming and sexual assault by the decedent to Mr. Stewart," the DA's office said in the release. Additionally, the DA's office said if the "jury was aware" of the relationship between Stewart and the teacher, then he would not have been sentenced to 60 years in prison. Therefore, the DA's office said "had there been an investigation into the facts as alleged by Mr. Stewart, there was insufficient evidence of Robbery." "These findings conclude that Mr. Stewart did not receive a fair trial, should be granted a new trial, and should be released from prison while awaiting a decision from the Texas Criminal Court of Appeals," the DA's office said in the release, The DA's office is holding a media briefing at 10 a.m. Thursday in the 299th District Court to provide more details on the case, the release said.