NASHVILLE, Tenn. (AP) — A Tennessee inmate scheduled to be executed in December continued to push Friday for DNA testing of the evidence in his case, arguing that would exonerate him.

Pervis Payne, 53, has always maintained his innocence in the 1987 stabbing deaths of Charisse Christopher and her 2-year-old daughter, Lacie Jo. Christopher’s son, Nicholas, who was 3 at the time, was stabbed but survived.

At the time of Payne's trial, DNA testing of evidence was unavailable, and no testing has ever been done in his case.

His attorneys initially filed a petition in July seeking to get DNA tests of the evidence, including the murder weapon and numerous blood-soaked items. Payne’s lawyers reviewed the bedding in December 2019 and included it in their DNA testing petition.

Shelby County District Attorney Amy Weirich is fighting the request, countering that the Tennessee Supreme Court has already ruled on DNA testing. She also has said the evidence against Payne is “overwhelming.”

According the Payne's response filed Friday, attorneys agree that the previous request for DNA testing in 2006 was refused but say that the high court's basis for that ruling has since been overturned.

“The Opposition also fails to address that if a DNA profile of an individual other than Mr. Payne or the victims appears on multiple pieces of crime scene evidence ... it would provide powerful proof that someone other than Mr. Payne was at the scene of the crime, thereby gutting the prosecution’s oft-repeated theory that Mr. Payne’s presence at the crime scene makes him the only possible perpetrator of the crime,” the filing states.

Payne told police he was at Christopher’s apartment building to meet his girlfriend when he saw a man in bloody clothes run past him. Payne, who is Black, has said he found and tried to help the victims, who were white, but panicked when he saw a white policeman and ran away.

Prosecutors said Payne was high on cocaine and looking for sex when he killed Christopher and her daughter in a “drug-induced frenzy.”

Weirich has said Payne’s baseball cap was found hanging on the girl’s arm, and there was blood on his body when he was arrested.

Payne’s petition says police focused almost exclusively on him as a suspect, although nothing in his history suggested he would commit such a crime. He was a minister’s son who was intellectually disabled and never caused problems either as a child or a teenager, his lawyers say.

Payne is scheduled to be executed on Dec. 3, but the method has not yet been announced. Tennessee is one of six states in which inmates can choose the electric chair over lethal injection, but it’s the only state that has used the chair in recent years.

Feb. 20 was the most recent execution in Tennessee, when Nicholas Sutton died in the electric chair.