Washington DC - The Supreme Court on Tuesday threw out the conviction and ordered a new trial for an Oklahoma man who has had three "last meals" since being sentenced to death for a murder he insists he did not commit.

Richard Glossip (62) was convicted – twice – of the 1997 murder-for-hire of Barry Van Treese, an Oklahoma City motel owner, and has spent more than 25 years on Death Row awaiting execution.

Glossip's high-profile case has drawn appeals for clemency from Pope Francis and a bevy of celebrities, including British billionaire Richard Branson and Hollywood stars Mark Ruffalo and Susan Sarandon.

The Supreme Court heard arguments in the case in October, and a majority of the nine justices tossed out Glossip's conviction on Tuesday, citing prosecutorial misconduct and questions about the credibility of a key witness.

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"The prosecution violated its constitutional obligation to correct false testimony," said Justice Sonia Sotomayor, who wrote the majority opinion, which was joined by four other justices – conservatives John Roberts and Brett Kavanaugh, and liberals Elena Kagan and Ketanji Brown Jackson.

"A new trial is the appropriate remedy," Sotomayor wrote.

Another conservative justice, Amy Coney Barrett, joined the majority opinion in part while the two arch-conservatives on the court, Clarence Thomas and Samuel Alito, dissented.

One justice, Neil Gorsuch, recused himself because he was involved in the Glossip case before joining the Supreme Court.

Glossip's first conviction, in 1998, was overturned because of ineffective counsel, but he was tried once more in 2004 and again found guilty.

His case wound up in the Supreme Court after the Republican attorney general of Oklahoma, in an unusual intervention, sought a new trial for Glossip, citing "grave misconduct" by prosecutors who withheld evidence and a star witness who lied on the stand about being prescribed lithium by a prison psychiatrist for bipolar disorder.

Glossip was convicted almost solely on the basis of testimony from Justin Sneed, the then-19-year-old motel maintenance man who confessed to bludgeoning Van Treese to death with a baseball bat in a plot he claimed was masterminded by Glossip, the motel manager.

The Oklahoma Court of Criminal Appeals rebuffed state Attorney General Gentner Drummond's appeal to vacate Glossip's conviction, and the Supreme Court agreed to hear the case.

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Don Knight, one of Glossip's attorneys, welcomed the top court's decision.

"We are thankful that a clear majority of the court supports long-standing precedent that prosecutors cannot hide critical evidence from defense lawyers and cannot stand by while their witnesses knowingly lie to the jury," Knight said.

"Today was a victory for justice and fairness in our judicial system," he said. "Rich Glossip, who has maintained his innocence for 27 years, will now be given the chance to have the fair trial that he has always been denied."

Execution dates for Glossip have been scheduled nine times over the years and he was served "last meals" on three occasions. Glossip was last scheduled to be put to death by lethal injection on May 18, 2023, but the Supreme Court stayed his execution.

There were 25 executions in the US last year, and there have been five so far this year.