These undated arrest photos made available by the Shreveport Police Department show Corey Williams under arrest. Defense attorneys are urging the nation's highest court to throw out a case in which they claim Louisiana prosecutors withheld evidence that an intellectually disabled 16-year-old boy falsely confessed to killing a pizza deliveryman in 1998. (Shreveport Police Dept. via AP)

BATON ROUGE, La. - A legal team has petitioned the U.S. Supreme Court to hear its claim that Louisiana prosecutors withheld evidence for a murder trial that ended in a guilty verdict against an intellectually disabled teenager accused of killing a pizza deliveryman.

Corey Williams was 16 years old when police arrested him in the shooting death of Jarvis Griffin two decades ago in Caddo Parish, where prosecutors have been widely criticized for their aggressive approach to seeking the death penalty.

Earlier this week, a group of 44 former prosecutors and Justice Department officials - former U.S. Attorney General Michael Mukasey among them - filed a brief in support of a petition by Williams' lawyers asking the court to review and reverse his murder conviction.

Before the shooting, Williams was hospitalized for extreme lead poisoning, still sucked his thumb and frequently urinated on himself, according to his lawyers. A district court judge overturned Williams' death sentence in 2004 on the basis of his disabilities, one of his attorneys said.

Lawyers for Williams say there wasn't any physical evidence linking him to the January 1998 death of Griffin, who was killed and robbed while delivering a pizza to a Shreveport home.

The petition claims "staggering" evidence of Williams' innocence was suppressed by prosecutors before his trial.

Caddo Parish prosecutors haven't filed a response to the petitions yet, but they have denied violating their duty to disclose evidence favourable to Williams.

Witnesses saw several older men steal money and pizza from Griffin and saw Williams running from the house alone with nothing in his hands after the shooting, according to his lawyers. One of the older men, Chris Moore, was the only witness who identified Williams as the shooter.

Fingerprints found on the murder weapon belonged to one of the other older men, and the victim's blood was found on clothing worn by a third older man, according to Williams' lawyers.

Police officers found Williams hiding under a sheet on a couch at his grandmother's house. He initially denied killing Griffin but changed his story after police questioned him through the night.

"His confession was brief, devoid of corroborating details," his lawyers wrote in their March 2 petition to the Supreme Court. "Having just assumed responsibility for a homicide, Corey told the officers, 'I'm tired. I'm ready to go home and lay down.'"

Williams' lawyers say his conviction was based primarily on that confession and the testimony of Moore. Only after Williams' trial did his attorneys obtain recordings of witness interviews pointing to his innocence. The withheld recordings showed police had suspected the older men were plotting to frame Williams for the killing, according to Williams' lawyers.

Supreme Court justices expressed concern about the suppression of evidence in a different Louisiana case it decided in 2012. The court voted 8-1 to reverse a conviction in a case in which New Orleans prosecutors similarly withheld a witness statement from the night of a murder because they decided it wouldn't alter the trial's outcome.

Dale Cox, Caddo Parish's former acting district attorney, said in a 2015 court filing that Williams hasn't proved the recorded witness statements contained "exculpatory" evidence or that withholding them deprived him of a fair trial.

"The State presented to the jury a confession that was wholly corroborated by eyewitness testimony," he wrote.

Cox, who once told a reporter he believes the state needs to "kill more people," personally prosecuted one-third of the Louisiana cases that resulted in death sentences between 2010 and 2015, according to the Death Penalty Information Center.

In a 4-2 vote last October, the Louisiana Supreme Court refused to hold a hearing on Williams' claims. His attorneys are asking the U.S. Supreme Court to review that decision.

News from © The Associated Press, 2018