BONNE TERRE, Mo. -- The U.S. Supreme Court stayed a condemned Missouri inmate's execution Wednesday evening, sending the case back to the 8th U.S. Circuit Court of Appeals.
Missouri officials told those who had planned to witness it to go home.
The high court granted the stay for Russell Bucklew "pending the disposition of petitioner's appeal. We leave for further consideration in the lower courts whether an evidentiary hearing is necessary."
Bucklew's death warrant was to expire at midnight in Missouri, but state officials called off the execution after the Supreme Court issued its order about 6 p.m. Witnesses were not told how soon to return, just that it would not be soon, a state witness told the Los Angeles Times.
A spokesman for the Missouri attorney general's office said no further litigation was expected Wednesday.
Bucklew, 46, suffers from a rare congenital condition -- cavernous hemangioma -- that causes weakened and malformed blood vessels, as well as tumors in his nose and throat.
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.
He told The Associated Press last week that he is scared of what might happen during the process.
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.
Earlier Wednesday, Supreme Court Justice Samuel Alioto blocked the execution while the full court considered the matter.
Mike O'Connell, a spokesman for the Missouri Department of Corrections, cautioned against reading too much into Alito's intervention.
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 window before the Supreme Court allowed the state to proceed.
One of them was executed nearly 23 hours after he originally was scheduled to die.
In a 2-1 ruling Tuesday suspending the execution, an 8th U.S. Circuit Court of Appeals 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." That was overruled later by the full court before Alito intervened.
"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 didn't get any help from Missouri Gov. Jay Nixon, a Democrat and death-penalty proponent who rejected Bucklew's clemency request late Tuesday.
European companies opposed to capital punishment cut off supplies of certain execution drugs, 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.
Missouri switched from a three-drug protocol to the single drug pentobarbital late last year.