Published: May 21, 2014 5:13 AM EDT

BONNE TERRE, Mo. (AP) - A Missouri inmate with a rare condition that affects the blood vessels got a reprieve less than two hours before his scheduled execution, but the state may end up killing him later Wednesday if U.S. Supreme Court says it can.
    
Russell Bucklew was scheduled to be executed at 12:01 a.m. Wednesday for the 1996 killing of a romantic rival. He would have been the first U.S. inmate put to death since last month's botched execution in Oklahoma, in which the prisoner's vein collapsed while the lethal drugs were being administered.
    
Bucklew, 46, has a condition that causes weakened and malformed veins, and his attorneys say this and the secrecy surrounding the state's lethal injection drug combine to make for an unacceptably high chance of something going wrong during his execution.
    
After an 8th U.S. Circuit Court of Appeals panel suspended the execution Tuesday, only to be overruled hours later by the full court, Supreme Court Justice Samuel Alito issued his own stay, setting the stage for the full high court to weigh the appeal. If the Supreme Court rejects the appeal, Missouri would have until midnight to carry out the execution.
    
Mike O'Connell, a spokesman for the Missouri Department of Corrections, cautioned against reading too much into Alito's intervention.
    
Alito handles emergency matters for states covered by the 8th Circuit, and two of the six inmates Missouri has executed since switching to a single-drug system in November had appeals that stretched well into the state's 24-hour execution window before they Supreme Court allowed the state to proceed. One of them was executed nearly 23 hours after he originally was scheduled to die.
    
Bucklew suffers from a rare congenital condition - cavernous hemangioma - that causes weakened and malformed blood vessels, as well as tumors in his nose and throat. He told The Associated Press by phone last week that he is scared of what might happen during his execution.
    
During Oklahoma's April 29 execution, inmate Clayton Lockett's vein collapsed, and he writhed on the gurney before eventually dying of a heart attack more than 40 minutes after the start of a procedure that typically takes roughly one-fourth of that time to complete.
    
In its 2-1 ruling, the 8th Circuit panel ruled that Bucklew's "unrebutted medical evidence demonstrates the requisite sufficient likelihood of unnecessary pain and suffering beyond the constitutionally permissible amount inherent in all executions."
    
"The state does not have the right to inflict extreme, torturous pain during an execution," Bucklew's attorney Cheryl Pilate said. "We still hope that Mr. Bucklew's grave medical condition and compromised airway will persuade the governor or a court to step back from this extremely risky execution."
    
Bucklew won't be getting help from Missouri Gov. Jay Nixon, a Democrat and death-penalty proponent who rejected Bucklew's clemency request late Tuesday.
    
European companies cut off supplies of certain execution drugs because of opposition to capital punishment, leading Missouri and other states to turn to U.S. sources. The states refuse to identify the sources of their execution drugs, saying secrecy is necessary to protect the sources from possible retaliation by death penalty opponents.
    
Death penalty opponents say the secrecy makes it impossible to ensure that the drugs couldn't cause an inmate to endure an agonizing death that rises to the level of unconstitutionally cruel and unusual punishment.
    
Missouri switched from a three-drug protocol to the single drug pentobarbital late last year. None of the six inmates executed since Missouri made the change has shown outward signs of pain or suffering.
    
The AP and four other news organizations filed a lawsuit last week against the Missouri Department of Corrections, claiming the state's refusal to provide information on the execution drug violates the public's constitutional right to have access to information about the punishment.
    
According to prosecutors, Bucklew was angry at his girlfriend, Stephanie Pruitt, for leaving him. Pruitt moved with her two daughters into the Cape Girardeau home of Michael Sanders, who had two sons. Bucklew tracked Pruitt down at Sanders' home March 21, 1996, and killed Sanders in front of Pruitt and the four children. He handcuffed and beat Pruitt, drove her to a secluded area and raped her.
    
Later, after a state trooper spotted the car, Bucklew shot at the trooper but missed, authorities say. Bucklew was grazed in the head and hospitalized. He later escaped from jail, hid in the home of Pruitt's mother and beat her with a hammer. She escaped, and Bucklew was arrested a short time later.

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