(CNN) Less than a month before Rodney Reed is set to be executed in Texas, a former prison inmate claims someone else confessed to the murder that sent Reed to prison.
Reed has spent more than 21 years on death row for the 1996 murder of Stacey Stites in Bastrop, Texas. Police say Reed assaulted, raped and strangled Stites, but he insists he's innocent. He is set to be executed on November 20.
Former inmate Arthur Snow Jr. filed an affidavit in court earlier this week saying Stites' fiancé, Jimmy Fennell, confessed to the murder years ago.
Snow had been serving a sentence for forgery at a DeWitt County, Texas, prison in 2010 when he made a deal with Fennell, who'd sought protection from other inmates, the document states. Snow was then a member of the Aryan Brotherhood gang, it states.
In his affidavit, Snow said he was with Fennell in the prison yard when Fennell started bragging about killing Stites.
"Jimmy said his fiancé had been sleeping around with a black man behind his back," Snow wrote.
"Toward the end of the conversation Jimmy said confidently, 'I had to kill my n*****- loving fiancé,'" he added. "My impression was the Jimmy felt safe, even proud, sharing this information with me because I was a member of the Aryan Brotherhood. I think Jimmy assumed that his confession would impress me and earn him credibility with the Aryan Brotherhood."
Snow said he learned about Reed's case a few years ago when, jailed in Texas' Hays County for a different offense, he saw a photo of Fennell along with an article about Reed in the newspaper.
Snow realized Reed was in prison for a murder that Fennell had confessed to him, Snow said in his affidavit.
While more recently in Hays County jail for another crime, Snow decided to come forward after he saw another article about the case, his affidavit said.
Fennell's attorney, Robert Phillips, said Snow is a career criminal and his claim is not credible nor in the "world of reality."
Fennell served time in prison for rape but has since been released, converted to Christianity and is helping people with drug addictions, Phillips said.
Police identified Fennell -- a former police officer -- as a suspect during their investigation into Stites' killing, but he was never charged.
Earlier this week, Reed's attorneys filed an application for clemency as they attempt to block his execution. Snow is among a few witnesses who have emerged in recent weeks suggesting that Reed is innocent.
Bryce Benjet, a senior staff attorney at the Innocence Project and Reed's lead counsel, said evidence clearly shows that Reed did not kill Stites.
"Mr. Reed's execution is less than one month away, meaning Texas is frighteningly close to executing an innocent man," Benjet said in a statement. Between the medical and scientific evidence, and multiple new, credible witnesses, the original case trial has been completely deconstructed and disproven."
Last month, reality TV star Kim Kardashian West urged Texas Gov. Greg Abbott to intervene in the case and "do the right thing" for Reed.