Marcellus Williams, a death row inmate in Missouri, is about to be executed despite new DNA evidence suggesting he is innocent.
The 48-year-old was found guilty of the August 1998 murder of Lisha Gayle, 42, at home in St Louis. He was convicted and sentenced to death three years later.
He is scheduled to be killed by lethal injection at 6pm on Tuesday (12am GMT).
However, new evidence suggests Williams may be innocent, as DNA found on the knife used to kill Ms Gayle does not match his.
Prosecutors claim Williams was burgling his victim’s home when she discovered him and he stabbed her repeatedly. He has always maintained his innocence.
Williams’ lawyers have now asked the US Supreme Court to intervene in a desperate final bid to stop his execution. They are also appealing to Missouri’s Republican governor, Eric Greitens, to grant him clemency.
His legal team says technology not available during the initial investigation shows DNA found on the murder weapon matches that of an unknown male and not Williams.
His lawyer, Kent Gimpson, told Al Jazeera:
“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.
“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.
“It was someone else that killed Gayle, not Williams.”