The execution of Marcellus Williams is set to proceed as scheduled Tuesday after the Missouri Supreme Court and the state's governor both rejected pleas to halt the procedure.

An attorney for Williams argued Monday that the state Supreme Court should halt the lethal injection because a trial attorney prevented a Black man who he thought looked similar to the defendant from serving on the jury. Williams is scheduled to be executed at 6 p.m. on Tuesday for the 1998 stabbing death of Lisha Gayle in the St. Louis suburb of University City.

Williams, 55, has asserted his innocence. But his attorney did not pursue that claim Monday before the state's highest court, instead focusing on alleged procedural errors in jury selection and the prosecution's alleged mishandling of the murder weapon.

The state Supreme Court should "correct an injustice" either by declaring that a prosecutor wrongly excluded a potential juror for racial reasons or by sending the case back to a lower court to determine that issue, attorney Jonathan Potts argued on behalf of Williams.

Republican Missouri Attorney General Andrew Bailey's office has argued for the execution to proceed. The trial prosecutor has denied that he had racial motivations in removing potential jurors and did nothing improper — based on procedures at the time — by touching the murder weapon without gloves after it had already been tested by a crime lab, Assistant Attorney General Michael Spillane said in arguments to the state Supreme Court.

Attorneys for Williams also have an appeal before the U.S. Supreme Court.

Williams had also requested clemency from Republican Gov. Mike Parson, an ask that focused largely on how Gayle's relatives want the sentence commuted to life in prison without parole. But Parson on Monday said the execution would proceed following the state Supreme Court's ruling.

"Capital punishment cases are some of the hardest issues we have to address in the Governor's Office, but when it comes down to it, I follow the law and trust the integrity of our judicial system," Parson said in a statement Monday. "Mr. Williams has exhausted due process and every judicial avenue, including over 15 hearings attempting to argue his innocence and overturn his conviction. No jury nor court, including at the trial, appellate, and Supreme Court levels, have ever found merit in Mr. Williams' innocence claims. At the end of the day, his guilty verdict and sentence of capital punishment were upheld. Nothing from the real facts of this case have led me to believe in Mr. Williams' innocence, as such, Mr. Williams' punishment will be carried out as ordered by the Supreme Court."

The NAACP had also urged Parson to stop the execution.

The execution would be the third in Missouri this year and the 100th since the state resumed executions in 1989.

Williams was less than a week away from execution in January 2015 when the state Supreme Court called it off, allowing time for his attorneys to pursue additional DNA testing.

He was just hours away from being executed in August 2017 when then-Gov. Eric Greitens, a Republican, granted a stay after reviewing DNA evidence that found no trace of Williams' DNA on the knife used in the killing. Greitens appointed a panel of retired judges to examine the case, but the governor stepped down over an unrelated scandal and that panel never reached a conclusion.

Questions about DNA evidence also led Democratic St. Louis County Prosecuting Attorney Wesley Bell to request a hearing challenging Williams' guilt. But days before the Aug. 21 hearing, new testing showed that the DNA evidence was spoiled because members of the prosecutor's office touched the knife without gloves before the original trial.

With the DNA evidence unavailable, Midwest Innocence Project attorneys reached a compromise with the prosecutor's office: Williams would enter a new, no-contest plea to first-degree murder in exchange for a new sentence of life in prison without parole.

Judge Bruce Hilton signed off on the agreement, as did Gayle's family. But at Bailey's urging, the Missouri Supreme Court blocked the agreement and ordered Hilton to proceed with an evidentiary hearing, which took place Aug. 28.

Hilton ruled on Sept. 12 that the first-degree murder conviction and death sentence would stand, noting that his arguments all had been previously rejected.

"There is no basis for a court to find that Williams is innocent, and no court has made such a finding," Hilton wrote.

On Tuesday, Williams' attorney argued that circumstances are different, because the trial prosecutor had not previously been questioned in court by Williams' attorney about the reason he removed a specific juror.

The prosecutor in the 2001 first-degree murder case, Keith Larner, testified at the August hearing that the trial jury was fair, even though it included just one Black member on the panel. Larner said he struck one potential Black juror partly because he looked too much like Williams. He didn't explain why he felt that mattered.

The clemency petition from the Midwest Innocence Project focuses heavily on how Gayle's relatives want the sentence commuted to life without parole. Parson, a former sheriff, has been in office for 11 executions, and has never granted clemency.

Prosecutors at Williams' original trial said he broke into Gayle's home on Aug. 11, 1998, heard water running in the shower, and found a large butcher knife. Gayle, a social worker and former reporter for the St. Louis Post-Dispatch, was stabbed 43 times when she came downstairs. Her purse and her husband's laptop computer were stolen.

Authorities said Williams stole a jacket to conceal blood on his shirt. Williams' girlfriend asked him why he would wear a jacket on a hot day. The girlfriend said she later saw the purse and laptop in his car and that Williams sold the computer a day or two later. Police have said they found Gayle's clothing and the computer in Williams' car.

Prosecutors also cited testimony from Henry Cole, who shared a cell with Williams in 1999 while Williams was jailed on unrelated charges. Cole told prosecutors Williams confessed to the killing and offered details about it.

Williams' attorneys responded that the girlfriend and Cole were both convicted of felonies and wanted a $10,000 reward. Parson on Monday said in a statement the girlfriend "never requested the reward for information."