Marcellus Williams will not be granted a pardon, he will be executed on Tuesday, says his lawyer

Marcellus Williams, on death row in Missouri since 2001, is scheduled to be executed on Tuesday after his final plea for clemency was denied on Monday, his lawyer said.

Williams is scheduled to die by lethal injection at 6 p.m. CT on September 24 after being convicted of murdering newspaper reporter Felicia Gayle in 1998.

Gayle, journalist at St. Louis Post-Dispatchwas found brutally murdered in her home in a University City, Missouri, gated community on August 11, 1998, PEOPLE previously reported. Investigators later determined that Gayle had been stabbed at least 43 times and died from 16 wounds to her head, neck, chest and abdomen.

Williams had long maintained his innocence in the murder. In late August, his lawyers appeared before a Missouri judge and sought to overturn his conviction and death sentence at an evidentiary hearing. According to the Innocence Project, his last request was denied after “it emerged that the prosecutor may have tampered with exculpatory DNA evidence.”

The St. Louis County District Attorney's Office, which convicted Williams, is now supporting his claims of innocence. In a 73-page joint brief filed over the weekend, county prosecutors and defense attorneys agree that there is no forensic evidence linking Williams to the 1998 stabbing murder of Felicia Gayle.

A jury of 11 whites and one black convicted Williams in 2001 of first-degree murder, burglary, armed criminal action and robbery. The Innocence Project alleges that the prosecutor removed six qualified black jurors from the jury pool through recusal notices.

Then-prosecutor Keith Larner explained those objections in court in August, testifying in a joint statement that he rejected a black juror because he thought the man resembled Williams, who is also black. He said they looked like brothers, in part because they were black men who wore glasses and had “piercing eyes.”

Republican Governor Mike Parson said in a recent statement after blocking the motion that “no jury or court, at the trial, appellate, or Supreme Court levels, has ever found Mr. Williams' claims of innocence to be valid.” USA Today reports.

Williams' attorney, Tricia Rojo Bushnell, said in a statement released on behalf of the Innocence Project: “Missouri is on the verge of executing an innocent man, an outcome that calls into question the legitimacy of the entire criminal justice system.”

According to the Death Penalty Information Center, Williams will be the ninth person to be executed in the United States.