Update: A few hours before Marcellus Williams was due to be executed Missouri Governor Eric Greitens issued a stay of execution.

On Tuesday night, the US state of Missouri is planning to execute Marcellus Williams despite a new report from a DNA expert that his lawyers argue supports his claim to innocence.



In 2001, Williams, who is now 48, was convicted of the 1998 killing of Lisha Gayle. But his lawyers say new DNA evidence could exonerate him. The Missouri Supreme Court, however, has refused to review that evidence.



Williams' lawyer, Kent Gipson, has described the Supreme Court's decision as "baffling".



"We petitioned the court to look at the new evidence on August 14th, and less than 24 hours later they decided based on the court files that the execution should go ahead anyway. This is unprecedented," Gipson told Al Jazeera.

Williams, who has always claimed he is innocent, was sentenced to death in 2001, three years after Gayle, a former newspaper reporter, was murdered in her home in a gated community in St Louis, Missouri. He was originally due to be executed on January 28, 2015, but Missouri's high court decided to postpone the execution to allow time for new DNA tests to be conducted.

Those tests showed that the male DNA on the murder weapon, a knife, was not Williams' but belonged to a third, unknown person.

"There is no physical evidence, no eyewitnesses that directly connect Williams to the murder, the DNA on the weapon wasn't his, the bloody footprint at the murder scene wasn't from Williams' shoe and was a different size, and the hair fibres found weren't his," said Gipson. "It was someone else that killed Gayle, not Williams."

How was Williams convicted?

During Williams' trial, the prosecution based its case on the testimonies of two people, Henry Cole and Laura Asaro. Cole had shared a cell with Williams after he had been taken into custody on suspicion of being involved in Gayle's murder. Cole said Williams had confessed to murdering the 42-year-old woman.

The other testimony was given by Laura Asaro, a convicted drug addict, who was Williams' short-term girlfriend at the time of the murder. She claimed, among other things, to have seen scratches on Williams neck that were made by the victim.

"These scratches would leave DNA traces on the victim, but Williams' DNA was not found underneath the victim's fingernails, just like it was someone else's DNA that was found on the murder weapon," said Gipson.



"She also claimed she saw Williams with the victim's driver's licence, which is impossible because Gayle's licence was left at the crime scene."

Gipson believes both may have been motivated to give false statements in the hope of receiving a financial reward. "The victim's family offered a reward of $10,000 for anyone with tips leading to the arrest of the person who murdered Lisha Gayle," Gipson explained. "They both got paid by the victim's family after their testimonies."

With no forensic or eye witness testimony linking Williams to the murder, the prosecution based its case on these two witnesses. "At the time, we didn't have the technology to do these DNA tests. But even now that there is indisputable scientific evidence exonerating Williams from the murder, the attorney general still thinks these testimonies hold more weight than the DNA evidence that shows Williams didn't commit this crime," Gipson said.

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One of those following this case closely is Sister Helen Prejean, a well-known opponent of the death penalty who came to international fame after she wrote the book Dead Man Walking, which was later made into a film.

Griffin Hardy, a spokesperson for Sister Helen Prejean's anti-death penalty organisation Ministry Against the Death Penalty, told Al Jazeera: "The fact of the matter is DNA evidence shows that Marcellus Williams was not involved in this crime. That means that there is a killer who may still be out in the community at large. Missouri should use its resources to apprehend the real killer instead of executing a man who didn't commit this crime."

Black defendant, white victim, white jury

A significant factor in this case, according to Gipson and Griffin, is Williams' race. The victim, Lisha Gayle, was a white woman. Williams is a black man who, according to the prosecution, killed Gayle when she caught him burglarising her home in St Louis, Missouri, the same district where the Ferguson protests against police brutality took place in 2014.

"The jury that found Williams guilty consisted of mostly white people. This district has a history of getting African Americans off juries, especially when the victim is white," Gipson said.



There were seven African Americans in the juror pool for Williams' trial, but the prosecution struck all but one of them off with the result that there were 11 white jurors and one black juror at his trial.

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Another issue is the funding of public defenders in Missouri. "This state ranks 49th out of 50 with regards to properly funding public defenders. The public defender that got Williams' case has publicly stated that he wasn't able to prepare properly, so he simply didn't have the opportunity to properly discredit the shaky testimonies that were used to build this case around," Gipson said.

As to why the court has refused to examine the new evidence, Gipson said: "It's baffling to me how the Missouri Supreme Court denied our petition barely 24 hours after filing it, with no hearing at all. Listening to what experts have to say about new evidence is particularly important in a case like this with scientific evidence. It is frightening that someone can have exonerating DNA evidence and a court would turn a blind eye to it."

Williams' execution can now only be stopped by the United States Supreme Court or the governor of Missouri, Eric Greitens. "He is a newly elected governor and he heavily campaigned on being pro-life. Anyone who says he is pro-life would not let anyone be executed, especially not when there is more than enough reasonable doubt like in this case," Gipson said.

Hardy hopes Governor Greitens will stop the execution and that a new investigation to find Lisha Gayle's killer will be launched.

"Society may debate the question of whether the death penalty is acceptable for guilty prisoners, but no one can argue with the fact that an innocent person should never be executed," he said.



Williams is due to be executed by lethal injection.

Al Jazeera contacted both the office of Missouri's attorney general, Josh Hawley, and the office of Missouri Governor Eric Greitens for this article. Neither had responded by the time of publication.