The Philadelphia death-row inmate who has become an unlikely poster child in the state's ongoing fight over the morality of capital punishment has received one more chance to potentially fend off his execution, thanks to the U.S. Supreme Court.

That court agreed Thursday to scrutinize the role played in the case by a major figure in the recent history of Pennsylvania courts and Philadelphia politics: Ronald D. Castille.

The high court announced it would take up the appeal by Terrance Williams, convicted in the 1984 beating death of a Germantown church deacon, who argues that Pennsylvania's former chief justice should not have taken part in a decision to uphold his punishment last year.

Williams' lawyers say Castille, who retired as the top judge on Pennsylvania's high court in 2014, should have recused himself when the case came before the state Supreme Court because Castille was Philadelphia's district attorney when Williams was condemned to die.

What's more, the inmate's lawyers argue, Castille repeatedly touted his record of having sent convicted murderers to death row during his first 1993 campaign for his state Supreme Court seat.

The U.S. Supreme Court's decision Thursday to weigh in is only the latest twist in a case that has since taken on political ramifications.

In February, Gov. Wolf cited Williams' case as he declared his moratorium on capital punishment in the state, saying his decision was "in no way an expression of sympathy for the guilty on death row" but rather one based on an "ineffective, unjust and expensive" system.

Critics of Wolf's decision have also held up Williams, a two-time murderer with a history of other violent crimes, as being as worthy a candidate as any for execution.

"We are gratified the Supreme Court has accepted Mr. Williams' petition and will take a close look at some of the egregious problems that have tainted his case from the beginning," said Shawn Nolan, Williams' lawyer and chief of the capital unit of the Federal Community Defender's Office in Philadelphia.

Castille, a decorated Vietnam veteran and career prosecutor who ran for mayor before winning his seat on the state high court, said Thursday night that he believed previous U.S. Supreme Court rulings were on his side.

Former prosecutors "do not have to recuse themselves from any case that's in their system if they move up to become a judge," he said. "What was I supposed to do, recuse myself from every case that came out of the Philadelphia District Attorney's Office? That's ridiculous."

Ronald Eisenberg, the deputy handling appeals in the Williams case for the Philadelphia District Attorney's Office, could not be reached for comment.

Williams, now 48, was an 18-year-old Cheyney University football standout when he was arrested in 1984 and charged with murdering Amos Norwood. At the time, city prosecutors alleged that he bludgeoned Norwood to death in a West Oak Lane cemetery, then set his corpse on fire, during a robbery.

Though Williams testified at his trial that he was innocent and had never met Norwood, he has since claimed through his lawyers that the killing was motivated by five years of sexual abuse he suffered at Norwood's hands as a teenager.

The case now before the U.S. Supreme Court centers on a 2014 hearing in which the Pennsylvania Supreme Court affirmed Williams' death sentence, despite a lower court's finding that prosecutors had withheld evidence that might have aided in his defense.

Just five days before Williams was to be executed in 2012, Common Pleas Court Judge M. Teresa Sarmina threw out his death sentence, saying prosecutors under Castille had failed to share - among other evidence - information that Norwood had sexually abused other teenagers he had met through his church.

But in a unanimous decision last year - Castille's final year on the bench before his mandatory retirement at age 70 - he and his colleagues on the state Supreme Court rejected her ruling, finding that Williams could have raised his sexual past with Norwood at his original trial, but instead had lied under oath and said he had never met the man.

Williams' lawyers sought Castille's recusal before that decision, but Castille rebuffed them.

In a separate opinion laced with withering criticism, the chief justice suggested Sarmina's court had become "unmoored from its lawful duty" and accused Williams' legal defense team of sidestepping procedural roles and "pursuing an obstructionist anti-death penalty agenda."

In filings with the U.S. Supreme Court in July, Eisenberg, the deputy district attorney, maintained that Castille "acted properly" in refusing to step aside from hearing Williams' appeal and that his vote was not a decisive factor in the state high court's decision. Castille's former role as district attorney posed no significant conflict of interest as Williams' case was just one of more than 250,000 Castille oversaw during his five-year tenure running the District Attorney's Office, Eisenberg argued.

"Given this enormous volume of cases, Chief Justice Castille has observed, it was impossible for him to be personally involved in the prosecution of every case handled by his office," Eisenberg wrote.

That argument did not move lawyer Marc Bookman, director of the Philadelphia-based nonprofit Atlantic Center for Capital Representation. He said that even if Castille thought he could rule impartially, his past involvement in the case created the appearance of a conflict of interest.

"How can that not make a difference to the other justices?" Bookman said. "It is his [Castille's] former office that is being accused of hiding evidence. He has a stake in protecting the office that he led at the time that all this happened."

Now the legal battle shifts to Washington, where sometime before the end of June, the Supreme Court will hear oral arguments and decide whether Castille's involvement in Williams' appeal was improper.

The former chief justice said he was in no position Thursday to read the tea leaves.

"Their law is pretty settled in this issue," he said. "Are they bringing up the case to reinforce the law, or [are] they bringing it up to change the law?".

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