Archbishop Christophe Pierre, nuncio to the United States, has urged Missouri Republican Gov. Mike Parson to respect "the humanity" of death-row inmate Ernest Lee Johnson and "the sacredness of all human life" and stop his Oct. 5 execution.

Writing to Parson on behalf of Pope Francis, the nuncio asked that he halt the scheduled execution and grant him "some form appropriate form of clemency."

"This request is not based upon the facts and circumstances of his crimes; who could not argue that grave crimes such as his deserve grave punishments?" Archbishop Pierre said in a Sept. 27 letter to Parson. "Nor is this request based upon Mr. Johnson's doubtful intellectual capacity. Rather His Holiness wishes to place before you the simple fact of Mr. Johnson's humanity and the sacredness of all human life."

Johnson, 61, who is African American, is scheduled to die by lethal injection at the state prison in Bonne Terre at 6 p.m. (local time) Oct. 5.

He was convicted of first-degree murder in 1995 and sentenced to death for killing three employees of a Columbia, Missouri, convenience store -- 46-year-old Mary Bratcher, 57-year-old Mable Scruggs and 58-year-old Fred Jones -- with a claw hammer.

His lawyer and advocates for clemency have argued that his execution would be unconstitutional because a 2008 operation for a brain tumor left him with a diminished intellectual capacity. Surgeons had to remove roughly one-fifth of his brain tissue.

Archbishop Pierre said that in issuing an "urgent plea" for clemency for Johnson, the pope was asking Parson "to consider that, when violence of all types is restrained, even the violence of a legal execution, all of society benefits."

"As Pope Francis cautioned in his encyclical letter 'Fratelli Tutti,' 'Do not let the atrocity of their sins feed a desire for vengeance, but desire instead to heal the wounds which those deeds have inflicted,'" he said.

Archbishop Pierre praised the state of Missouri for the "courageous stands" it has taken "in support of the dignity of life, even at its earliest and most vulnerable stage."

"For this we are very grateful," he wrote. "Now, to reject the application of the death penalty in the case of Mr. Johnson, would be an equally courageous recognition of the inalienable dignity of all human life.

"Indeed, Pope Francis has observed that "if I do not deny the human dignity of the worst criminals, I will not deny human dignity to anyone.' Is not a universal recognition of our sacred human dignity the best possible defense for society against the war and violence in our world?"

Channel 41 KSHB in Kansas City, Missouri, reported that Parson "was still weighing clemency" as of Oct. 1. Johnson's lawyers also have asked the Missouri Supreme Court to reconsider the case.

Others were urging Parson to halt the execution including a previous governor, Democrat Bob Holden, who held the office for one term, 2000-2004. Saying generally he supports capital punishment, he agreed with Johnson's lawyer that his client has diminished intellectual capacity.

U.S. Reps. Cori Bush and Emanuel Cleaver II, both Missouri Democrats and members of the Congressional Black Caucus, also have called for clemency.