Pleas from the Pope to grant a death row inmate clemency have been ignored with his execution set to go ahead as planned on Tuesday.
Ernest Lee Johnson, 61, is awaiting execution over the murders of three people in a convenience store in 1994.
Announcing the execution order, Missouri Governor Mike Parson said: “The state is prepared to deliver justice and carry out the lawful sentence Mr Johnson received in accordance with the Missouri Supreme Court’s order.”
It comes a week after a representative for Pope Francis wrote to Parson saying the Pontiff “wishes to place before you the simple fact of Mr Johnson’s humanity and the sacredness of all human life.”
Pope Francis has been a critic of capital punishment, and in 2018 changed church teachings to decree the death penalty can never be allowed as it constitutes an “attack” on human dignity.
Johnson's lawyers have argued he is intellectually disabled, saying he has a significantly reduced intellectual capacity.
They also said he was born with fetal alcohol syndrome and lost about 20 per cent of his brain tissue in 2008 after he had a benign brain tumour removed.
In the United States, the eighth amendment bans intellectually disabled people being executed.
Johnson was convicted in 1995 of the murder of three convenience store workers in Columbia as they shut up shop in February of 1994.
He shot employees Mabel Scruggs and Fred Jones and their manager Mary Bratcher with a claw hammer and also stabbed Bratcher in the hand with a screwdriver.
Police searched his girlfriend's house after the murders, finding a bag with $443 (£325), coin wrappers, partially burned checks and shoes which matched bloody prints left at the scene of the crime.
Johnson admitted killing the three workers, but his lawyers have argued executing him would breach the eight amendment.
Two Congress members, Cori Bush (D-Mo.) and Emanuel Cleaver (D-Mo.), have also called for clemency.
“Mr Johnson’s execution would be a grave act of injustice. Killing those who lack the intellectual ability to conform their behaviour to the law is morally and legally unconscionable,” they wrote.
“Furthermore, Johnson was diagnosed with a brain tumour in 2008 and underwent brain tissue removal, according to court records. Scar tissue from the removal will likely cause him painful seizures after he is injected with pentobarbital, a seizure-inducing medication.”
“For all these reasons, we are staunch in our belief that Mr. Johnson should be granted clemency because he ― like any person ― is worthy of retribution and care.”
Johnson's execution is scheduled for 6pm local time (midnight BST).
