NASHVILLE, Tenn. (AP) — A Tennessee inmate scheduled to be executed in December asked a Shelby County court on Wednesday to order DNA testing of the evidence in his case.

Pervis Payne 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 also stabbed but survived. 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 African American, 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.” At the time of his trial, DNA testing of evidence was unavailable, and no testing has ever been done in his case. A previous request for DNA testing in 2006 was refused based on a Tennessee Supreme Court ruling that has since been overturned.

Shelby County District Attorney General Amy Weirich issued a statement Wednesday saying that her office is reviewing the allegations in the petition and preparing a response.

Payne's Wednesday 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 never caused problems either as a child or a teenager.

“Mr. Payne was close with his family and active in his church. He was a respected young man in his neighborhood, and although he struggled academically in school on account of his intellectual disability ... he never had any disciplinary issues,” according to the petition.

The petition also questions the assertion that Payne used cocaine on the day of the murder, saying the police report detailing his arrest made no mention of suspected drug use.

“Moreover, the perpetrator and Charisse Christopher engaged in a close-range violent struggle,” the petition states. “The kitchen where the victims were found was covered in blood, including on the walls and doors. The minor amount of blood present on Mr. Payne’s clothing is inconsistent with him being the perpetrator.”

The petition states there were other people with both the motive and opportunity to kill Christopher including a drug dealer to whom Christopher allegedly owed money and Christopher's abusive ex-husband.

The court must order the DNA testing, the petition argues, because Payne's case meets the requirements for testing under the law, including that evidence is available that has never been tested. The evidence includes the murder weapon and numerous blood-soaked items. Payne is also seeking to have fingerprints from the crime scene checked against FBI and Tennessee Bureau of Investigation databases.