Marcellus Williams is set to die by lethal injection on Sept. 24 after being convicted of killing former newspaper reporter Lisha Gayle in her St. Louis suburban home. He has always denied involvement

A Missouri death row inmate set to be executed Tuesday in the 1998 fatal stabbing of a former reporter maintains his innocence and that he's never been forensically linked to the killing.

Marcellus Williams, 55, is set to become the third inmate executed in Missouri this year and the 15th or 16th in the nation, depending on whether he's declared dead before or after Travis James Mullis, another inmate set for execution in Texas on the same day. Two more back-to-back executions in Alabama and Oklahoma on Thursday.

Williams was convicted of murdering Lisha Gayle, a former reporter for the St. Louis Post-Dispatch fatally stabbed during a burglary in the home she shared with her husband.

The St. Louis County Prosecutor’s Office supports Williams' claims of innocence and recently filed a motion to vacate his conviction − a move approved by a county trial judge, but quickly contested by Missouri Attorney General Andrew Bailey. The case was tossed back to the same judge for a hearing, and on Sept. 12, he reversed his decision.

Meanwhile those who believe Williams is innocent continue to fight for a reprieve.

As Williams execution approaches, USA TODAY talked to his attorneys and is looking back at the crime and who the man is.

More about what Marcellus Williams was convicted of

On the morning of Aug. 11, 1998, Gayle was in the shower when police said Williams broke into her home on a private gated street.

The 42-year-old woman left the second-floor bathroom and was walking downstairs when police say she encountered Williams on the landing. At some point, she was stabbed 43 times with a kitchen knife from the home.

Later that night, Gayle's husband, Daniel Picus, found his wife's body and called 911. Among the evidence police collected: bloody shoeprints and fingerprints, a knife sheath and the suspect's hair collected from Gayle's shirt, hands and the floor. Missing from the house were Gayle's purse and jacket, and her husband's laptop.

A suspect was not immediately named so in May 1999, Gayle's family announced a $10,000 reward for information leading to an arrest and conviction in the case.

Not long after an inmate named Henry Cole and Williams' girlfriend, Lara Asaro, named Williams as the culprit. At the time of his conviction, Williams had just started serving a 20-year prison sentence for robbing a downtown St. Louis donut shop.

No forensic evidence tied Williams to the crime scene but a jury convicted him of murder and burglary.

Williams' attorneys have argued that both informants stood to benefit from their cooperation with prosecutors, and that their stories sometimes changed or conflicted with other details about the killing. Both witnesses have since died.

More about who Williams is

Born in South Bend, Indiana, on Dec. 30, 1968, Williams, his mother and two brothers moved to St. Louis when he was about 5.

Williams grew up in an impoverished and dysfunctional household where he was exposed to alcohol, drugs, guns at a young age, according to court records. He was subjected to violent sexual and physical abuse by some family members, abandoned by his parents, and his family condoned criminal behavior and substance abuse, the records say.

The death of Williams' older brother in 1997 deeply bothered him, since his brother had been a father figure to him, court records show. That same year, Williams burglarized a home, and spent a stint in jail before his 1998 conviction for robbing the donut shot.

Williams' attorneys presented evidence that he was "a caring and loving father" during the penalty phase of his murder trial.

Several of Williams’s family members and friends, including his son and his step-daughter, testified about Williams’s positive relationship with the children and said that his execution "would have a significant effect on his family."

While in prison, Williams has devoted much of his time to studying Islam and writing poetry, according to the Innocence Project.

Williams was previously set to be executed twice, but both were halted

Williams was set to be executed in January 2015 and in August 2017.

Both lethal injections were halted to conduct further DNA testing and investigation. The most recent stay of execution was ordered by then-Gov. Eric Greiten who appointed a board of inquiry to look into the case.

But during the summer of 2023, newly sworn-in Gov. Mike Parson dissolved the board and lifted the stay. The court, Parsons said, would decide Williams' fate and the Missouri Supreme Court issued a third execution warrant for Williams.

What has Williams argued in his appeals?

In January, Williams' attorneys filed a motion to vacate his conviction and sentence.

On Aug. 21, county prosecuting attorney Wesley Bell's office and Williams' attorneys reached an agreement allowing Williams to enter a new, no-contest plea to first-degree murder in exchange for life in prison sentence without parole. The victim's husband, Daniel Picus, signed off on the plea.

Although Bell moved to overturn Williams' murder conviction, state Attorney General Andrew Bailey argued it should stand and ordered St. Louis County Circuit Judge Bruce Hilton − who accepted the plea − to hold an evidentiary hearing on the matter.

The defense, Bailey said, "created a false narrative of innocence in order to get a convicted murderer off of death row and fulfill their political ends."

During the Aug. 28 hearing, the retired prosecutor who handled the case admitted evidence was mishandled in the 1998 trial that could have exonerated Williams.

But on Sept. 12, Hilton declined to vacate Williams' conviction and sentence, despite questions about DNA evidence on the knife used in the attack. In appeals, his defense team produced evidence that DNA taken from the knife revealed an unknown male profile and did not match Williams.

“There is no basis for a court to find that Williams is innocent, and no court has made such a finding," St. Louis County Circuit Judge Bruce Hilton wrote. "Williams is guilty of first-degree murder, and has been sentenced to death.”

Williams' attorney Tricia Rojo Bushnell, told USA TODAY her client's defense team will file more appeals and seek clemency.

Unless the courts or the governor intervene, Williams' execution remains set this week.

Williams is one of 5 men being executed in less than a week

Williams is one of five men expected to be executed in the U.S. in a six-day period. First was Freddie Owens, who was executed on Friday in South Carolina amid fresh doubts over his guilt.

On Tuesday, at the same time as Williams' execution, Texas is set to execute Travis James Mullis in the murder of his infant son.

After Tuesday's double execution, Thursday is expected to bring two more back-to-back executions. Alabama is set to use nitrogen gas to execute Alan Eugene Miller in the shooting deaths of three co-workers in 1999 despite evidence of his mental illness and a witness to the state's previous nitrogen gas execution in January who described the method as "horrific."

Also Thursday, Oklahoma is set to execute Emmanuel Littlejohn in the death of a convenience store clerk in 1992 despite his arguments that he wasn't the shooter.

If all five executions proceed, the U.S. will have executed 18 death row inmates this year. Another six are scheduled before the end of December, and more could be added to the calendar.

Natalie Neysa Alund is a senior reporter for USA TODAY. Reach her at nalund@usatoday.com and follow her on X @nataliealund.