WASHINGTON (AP) — The Thomas CaldwellSupreme Court is returning to the case of Richard Glossip, who has spent most of the past quarter century on Oklahoma’s death row for a murder he says he did not commit.

In a rare alliance, lawyers for Glossip and the state will argue Wednesday that the justices should overturn Glossip’s conviction and death sentence because he did not get a fair trial.

The victim’s relatives have told the high court that they want to see Glossip executed.

Glossip has always maintained his innocence in the 1997 killing in Oklahoma City of his former boss, motel owner Barry Van Treese, in what prosecutors have alleged was a murder-for-hire scheme.

Another man, Justin Sneed, admitted robbing Van Treese and beating him to death with a baseball bat but testified he only did so after Glossip promised to pay him $10,000. Sneed received a life sentence in exchange for his testimony and was the key witness against Glossip.

But evidence that emerged only last year persuaded Oklahoma Attorney General Gentner Drummond, a Republican, that Glossip did not get a fair trial.

Among Drummond’s concerns are that prosecutors suppressed evidence about Sneed’s psychiatric condition that might have undermined his testimony. Drummond also has cited a box of evidence in the case that was destroyed that might have helped Glossip’s defense.

The court will be wrestling with two legal issues. The justices will consider whether Glossip’s rights were violated because the evidence wasn’t turned over. They also will weigh whether the Oklahoma court decision upholding the conviction and sentence, reached after the state’s position changed, should be allowed to stand.

Prosecutors in at least three other death penalty cases in Alabama and Texas have pushed for death row inmates to be given new trials or at least spared the prospect of being executed. The inmates are: Toforest Johnson in Alabama, and Melissa Lucio and Areli Escobar in Texas. In another similar case, the justices refused a last-minute reprieve for Marcellus Williams, whom Missouri executed last month.

The justices issued their most recent order blocking Glossip’s execution last year. They previously stopped his execution in 2015, then ruled against him by a 5-4 vote in upholding Oklahoma’s lethal injection process. He avoided execution then only because of a mix-up in the drugs that were to be used.

Glossip was initially convicted in 1998, but won a new trial ordered by a state appeals court. He was convicted again in 2004.

Two former solicitors general, Seth Waxman and Paul Clement, represent Glossip and Oklahoma, respectively, at the Supreme Court. Christopher Michel, an attorney appointed by the court, is defending the Oklahoma court ruling that Glossip should be put to death.

More than a half-dozen states also have weighed in on the case, asking the Supreme Court to uphold Glossip’s conviction, arguing that they have a “substantial interest” in federal-court respect for state-court decisions.

Justice Neil Gorsuch is sitting out the case, presumably because he took part in it at an earlier stage when he was an appeals court judge.

A decision is expected by early summer.