JEFFERSON CITY, Mo. (AP) — The Missouri Supreme Court on Friday ruled that execution plans for Marcellus Williams will move forward, even as a prosecutor works to overturn his 1998 murder conviction.

Judges on Friday decided against halting Williams’ execution despite a St. Louis County court hearing set for Aug. 21 to determine whether he is innocent.

Williams was convicted of first-degree murder in the 1998 death of Lisha Gayle during a robbery of her suburban St. Louis home.

St. Louis County Prosecuting Attorney Wesley Bell filed a motion in January to vacate Williams’ conviction. Bell cited new DNA evidence and said he believed Williams was not involved in Gayle’s death.

A 2021 Missouri law allows prosecuting attorneys to file a motion to vacate a conviction if they believe the inmate could be innocent or was otherwise erroneously convicted. The filing prompts a hearing before a judge.

In the meantime, Williams had asked the Supreme Court to stay his execution pending the outcome of the August hearing. He faces execution Sept. 24.

Judges ruled that they do not have the procedural authority to withdraw the execution order at this time.

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Williams’ attorney Tricia Bushnell in a statement said she’s “confident that any court, when presented with all the evidence—including the DNA evidence—will come to the same conclusion as St. Louis County Prosecutor Wesley Bell: that Marcellus Williams is innocent and his conviction must be overturned.”

“There is still time to right this wrong,” she said. “No one wants to see Missouri execute an innocent man.”

Bell said in a statement that his office is focused on the upcoming innocence hearing.

“While of course we would prefer that this motion before the Missouri Supreme Court had prevailed and there were no longer an execution date looming for Marcellus Williams, our focus is on the motion we filed before the 21st Judicial Circuit and the effort to have our concerns about the conviction of Mr. Williams heard in court,” Bell said.

A spokeswoman for the Missouri Attorney General’s Office did not immediately respond to a request for comment from The Associated Press on Friday.