After the court’s decision, an attorney for Williams listed people who had opposed his execution and fought for his removal from death row, including the St Louis County prosecutors who “now admitted they were wrong and zealously fought to undo the conviction and save Mr Williams’ life”.

“That is not justice,” Tricia Rojo Bushnell said. “And we must all question any system that would allow this to occur. The execution of an innocent person is the most extreme manifestation of Missouri’s obsession with ‘finality’ over truth, justice and humanity at any cost.”

But for Missouri Attorney General Andrew Bailey and Governor Mike Parson, Republicans who opposed efforts to overturn Williams’conviction, the state long ago met its burden in finding Williams guilty.

The National Association for the Advancement of Coloured People (NAACP), which had supported Williams’ attempt to leave death row, called the execution a lynching.

“Tonight, Missouri lynched another innocent black man,” NAACP president Derrick Johnson said. “When DNA evidence proves innocence, capital punishment is not justice – it is murder.”

Why was Marcellus Williams on death row?

On August 11, 1998, Felicia “Licia” Gayle, a former reporter for the St Louis Post-Dispatch, was found stabbed to death in her suburban St Louis home. Though forensic evidence at the crime scene included fingerprints, footprints, hair and DNA on a kitchen knife, the investigation stretched on for more than a year without an arrest.

Williams, who denied killing Gayle, was eventually convicted of her murder despite his DNA not matching the forensic evidence recovered from the crime scene. His current attorneys said his conviction was built upon testimony from two unreliable witnesses who had incentives to point the finger at Williams: reward money and a bargain for shorter sentences in their own criminal cases.

The Midwest Innocence Project, which took up Williams’s case, said the incentives of the witnesses in his case were particularly problematic. Jailhouse informant testimony played a role in 23% of death penalty exoneration cases, according to data from the National Registry of Exonerations at the University of Michigan.

What happened recently with Williams’ case?

Williams was twice spared from execution, first by the state Supreme Court in 2015 and in 2017 when Governor Eric Greitens granted Williams a reprieve.

Persuaded by arguments that new DNA testing exonerated Williams, Greitens appointed a board of inquiry to investigate the new claims. The board was abruptly disbanded in 2023 by Greitens’ successor, Parson, before it issued a final report. Bailey, the Attorney General, set a 2024 execution for Williams.

Parson said last year that it was “time to move forward” with the execution.

“We could stall and delay for another six years, deferring justice, leaving a victim’s family in limbo, and solving nothing,” Parson said in a press release last year. “This administration won’t do that.”

Williams sued Parson in August 2023 for dissolving the board before it could issue a report, but the state Supreme Court dismissed Williams’ claim, clearing the way for the execution.

St Louis County prosecuting attorney Wesley Bell in recent months became among the staunchest supporters of Williams’ claim after a DNA analysis excluded Williams as the source of DNA on the murder weapon.

Bell said his predecessors made constitutional errors that contributed to a faulty murder conviction. Those errors, according to Bell’s motion to vacate the conviction, were the prosecution’s mishandling of key physical evidence and the office’s use of witnesses who had personal and financial incentives to testify against Williams.

He said new DNA testing could have exonerated Williams.

But hours before a hearing on the evidence, Bell and Williams’ team learned the DNA that excluded Williams belonged to former St Louis prosecutor Keith Larner and an investigator who, years earlier, contaminated the murder weapon by handling it without gloves, according to court filings.

Bell’s office then sought to spare Williams the death penalty with an “Alford plea”, which would allow Williams to plead guilty without admitting to the crime and would result in life in prison. The state Supreme Court and Bailey blocked the deal.

This month, Williams’ attorneys argued before a St Louis County Circuit Court judge that the prosecution’s mishandling of evidence years ago “destroyed [Williams’] last and best chance” to prove his innocence, attorney Jonathan Potts said, according to the Associated Press. The circuit court judge declined to vacate Williams’ conviction and death sentence.

Parson rejected Williams’s clemency request, while the state Supreme Court on Monday rejected his request to pause his execution so a lower court could determine whether prosecutors wrongly excluded black potential jurors at his criminal trial.

Lawmakers including Missouri representative Cori Bush also urged the state to stop Williams’ execution.