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A day before his scheduled execution, a Missouri death row inmate could learn whether his fate will change after the state Supreme Court hears arguments in his case.

Marcellus Williams, 55, was convicted of killing former newspaper reporter Felicia Gayle, who was found stabbed to death in her home in 1998.

Williams has long maintained his innocence. And in an unusual move, St. Louis County’s top prosecutor filed a motion in January to overturn Williams’ 2001 conviction and sentence.

State Attorney Wesley Bell and Williams’ lawyers filed a joint brief Saturday asking the Missouri Supreme Court to remand the case to a lower court for a “more comprehensive hearing” of the January motion filed by Bell, a Democrat who is now running for Congress.

The case raises the risk that a potentially innocent person will be executed – an inherent risk of the death penalty. At least 200 people sentenced to death since 1973 have later been acquitted, including four in Missouri, according to the Death Penalty Information Center.

The hearing in Williams’ case before the Missouri Supreme Court is scheduled for Monday at 9 a.m. CT. Unless the courts or Republican Gov. Michael Parson intervene, Williams is scheduled to be executed on Tuesday at 6 p.m. CT.

The NAACP and the Council on American-Islamic Relations called on Parson to stop Williams’ execution. The governor had previously revoked a stay of execution in the case ordered by his predecessor, allowing Williams’ execution to go ahead.

In their joint brief, attorneys for Bell and Williams argue that the St. Louis County District Court failed to accept newly introduced evidence that contradicted prosecutors’ statements in Williams’ 2001 trial and in his earlier appeals.

The prosecution prosecuting Williams argued in a January motion that DNA analysis of the murder weapon could rule out Williams as Gayle’s killer. But that argument fell apart last month when new DNA analysis showed the murder weapon had been improperly handled, tainting the evidence intended to exonerate Williams and complicating his attempt to prove his innocence.

The brief also says the court erroneously ruled that the prosecutor’s tampering with DNA evidence did not violate Williams’ fair trial rights. And the attorney general’s efforts to block a retrial of Williams’ conviction may have prejudiced the district court proceedings, the brief’s authors say.

The attorneys asked the Missouri Supreme Court to overturn the district court’s decision and remand the case for a new hearing to give both sides time to present evidence and the court enough time to carefully review the case.

Williams’ lawyers also asked the U.S. Supreme Court last week for a stay of execution, arguing that he was denied his due process rights during the years-long legal battle to save his life.

When Parson took office, he dissolved the board and revoked Williams’ stay of execution, the petition says. In doing so, he effectively denied Williams his right to due process, Williams’ lawyers said.

They also pointed out that former Republican Gov. Eric Greitens had previously placed an indefinite stay on Williams’ execution and formed a panel to investigate his case and decide whether he should be granted clemency. “The panel investigated Williams’ case for the next six years – until Gov. Michael Parson abruptly ended the proceedings,” the lawyers wrote.

“The Governor’s actions violated Williams’ constitutional rights and required the Court’s attention with extraordinary urgency,” the court documents say.

Prosecutors have sought to overturn Williams’ conviction because “overwhelming evidence” showed that Williams’ trial was unfair, said one of his lawyers, Tricia Rojo Bushnell.

Prosecutors have raised other objections to Williams’ conviction, including that he was convicted based on the testimony of two unreliable informants who were facing legal troubles of their own and who also received a $10,000 bounty.

But ultimately, a state judge denied Bell’s request to overturn Williams’ conviction and sentence.

“There is no basis for a court to find Williams innocent,” Judge Bruce F. Hilton wrote in his ruling, “and no court has made such a finding. Williams is guilty of first-degree murder and was sentenced to death.”

In the case, Bell, who took office in 2018, faces Republican Attorney General Andrew Bailey, who is running for re-election. Bailey had fought Bell’s January motion, arguing that new DNA test results suggested the evidence did not exonerate Williams.

Last month, Bell’s office announced it had reached a settlement with Williams. Under the settlement, approved by the court and Gayle’s family, the inmate would have entered an Alford guilty plea to first-degree murder and received a life sentence.

But the state’s attorney general opposed the deal and appealed to the state Supreme Court, which blocked the agreement.

CNN’s Dakin Andone and Lauren Mascarenhas contributed to this report.