A Missouri inmate is scheduled to be put to death Tuesday evening for killing a man during a 1996 crime spree — but his rare disease that causes blood-filled tumors in his head, neck and throat may halt his execution.

Gov. Mike Parson, a Republican supporter of the death penalty, must decide if the risk posed by Russell Bucklew’s medical condition — cavernous hemangioma — is severe enough to grant the condemned man clemency.

“These unstable tumors are highly likely to hemorrhage during the stress of the execution, causing Russell to cough and choke on his own blood,” his attorney’s clemency request states.

A permanent tracheostomy in Bucklew’s throat helps him breathe.

In April, the US Supreme Court gave the go-ahead for Bucklew to be executed, so court appeals have apparently been exhausted. The execution would be the first in Missouri since January 2017.

Missouri uses a single dose of pentobarbital for executions but refuses to say where it gets it.

The source is believed to be a compound pharmacy, since large pharmaceutical companies prohibit the use of their drugs in executions.

It was unclear if the Missouri Department of Corrections planned any extra precautions to address the risk that Bucklew could suffer, in violation of the Eighth Amendment to the US Constitution.

A department spokeswoman said aspects of the state protocol are confidential, including what medical officials are involved.

Bucklew was within hours of execution in 2014 and again in 2018, only to get reprieves from the US Supreme Court due to concerns about whether he might suffer.

Human rights groups and death penalty opponents such as the four Roman Catholic bishops in Missouri and the American Civil Liberties Union have urged Parson to intervene.

Shortly after last year’s reprieve, Bucklew contracted meningitis, requiring insertion of the tracheostomy tube, according to one of his attorneys, Jeremy Weis, who said the tube is narrow and could fill with blood if the tumors burst.

Bucklew’s girlfriend, Stephanie Ray, left him on Valentine’s Day 1996.

In the following weeks, he harassed her, cut her with a knife and punched her in the face, according to court records.

Fearing for her life and the lives of her children, Ray moved into a mobile home that her new boyfriend, Michael Sanders, shared with his children.

On March 21, after swiping his nephew’s car and taking two handguns, handcuffs and duct tape from his brother, Bucklew followed Ray to the mobile home, where Sanders confronted him with a shotgun.

Bucklew fired two shots, one piercing Sanders’ lung. He bled to death.

Bucklew then shot at Sanders’ 6-year-old son and missed. He struck Ray in the face with the pistol, cuffed her, dragged her to his car and later raped her.

A trooper spotted Bucklew’s car and eventually became engaged in a gunfight near St. Louis. Both men were wounded. Bucklew later escaped from jail and attacked Ray’s mother and her boyfriend with a hammer before being recaptured.

With Post wires