Missouri Governor Eric Geitens has delayed the execution of Marcellus Williams after DNA evidence has come to light in the murder case of Lisha Gayle.
He was scheduled to be killed by lethal injection at 6pm on Tuesday (12am GMT).
The Missouri Supreme Court had delayed his execution in 2015 to allow for further DNA testing, but the state was planning to proceed with it despite the new evidence.
His attorneys have now appealed Mr Williams case to the US Supreme Court to either get a new hearing taking into account the DNA evidence or a commutation of his life sentence.
Ms Gayle, a former reporter for the St. Louis Post-Dispatch who became a social worker, was killed during an 11 August 1998 robbery at her home in a gated community in a suburb of St Louis.
Genetic testing done in December 2016, not available at the time of death, showed an unknown third person’s DNA on the murder weapon other than that of Mr Williams and Ms Gayle.
Lawyer Kent Gipson also cited previous DNA testing of hairs found from Gayle’s shirt and fingernails that also excluded Williams, and said footprints at the scene did not match Williams.
The conviction was based on the testimony of two convicted felons – Henry Cole and Laura Asaro – who were set to receive $10,000 as a reward from the victim’s family for information on the case, according to Mr Gipson.
Ms Asaro was Mr Williams’ former girlfriend who said she saw scratches on the back of his neck following Ms Gayle’s death. She also said she saw Ms Gayle’s driver’s licence with Mr Williams, however that document was found by police among items in Ms Gayle’s home.
Mr Cole was a former cellmate from when Mr Williams was first taken into police custody on suspicion of his role in Ms Gayle’s death. He said Mr Williams had confessed the murder to him.
“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,” he told Al Jazeera.
In addition to the murder conviction, Mr Williams is also serving consecutive terms of life in prison for robbery and 30 years each for burglary and weapons crimes.
St Louis County prosecutor Bob McCulloch has said that there is “zero possibility” that Mr Williams is innocent.
He claimed the DNA evidence Mr Gipson and his team have cited is inconclusive.
After several years of being among the states with the highest number of executions, the pace in Missouri has slowed considerably. The only execution in this state this year was in January, when Mark Christeson was put to death for killing a woman and her two children.
Missourians for Alternatives to the Death Penalty and Missouri NAACP officials had delivered copies of more than 185,000 signatures ahead of Mr Greitens’ decision.