A convicted Virginia serial killer's legal efforts to avoid execution on Thursday were rejected by the U.S. Supreme Court and a federal appeals court.
Alfredo Prieto, a 49-year-old native of El Salvador, had been scheduled to be executed at 9 p.m. at the Greensville Correctional Center.
His lawyers late on Thursday filed a new appeal with the U.S. Supreme Court arguing that pentobarbital, the first of the three lethal drugs used in the execution, might not anesthetize him enough.
Prieto was convicted in two 1988 Virginia murders and had been on death row in California. Virginia officials said in court filings he had been convicted of killing or suspected of killing at least nine people.
The 4th U.S. Circuit Court of Appeals upheld without comment a ruling earlier on Thursday by federal District Judge Henry Hudson that lifted a temporary order halting the execution.
Hudson rejected claims by Prieto's lawyers that pentobarbital used by Virginia officials might not be potent or sterile enough to prevent the inmate from feeling severe pain during the lethal injection.
Hudson said Virginia prisons officials had stored and transported the drug appropriately when they obtained it from Texas corrections authorities. He cited the public interest in orderly justice and said Prieto had waited years to make an 11th-hour challenge to his execution.
The U.S. Supreme Court earlier rejected without comment a bid for a stay of execution. Prieto's lawyers had said it would allow time for courts in California to rule on Prieto's claim that he is intellectually disabled.
They argue that Prieto has an IQ of 66 and is constitutionally exempt from execution.
Prieto was convicted in 2010 of the 1988 murders of Rachel Faver and her boyfriend, Warren Fulton, in Fairfax County, a Washington suburb. Faver had been raped.
Prieto was facing a 1992 death sentence in California for raping and murdering a 15-year-old girl when he was convicted in Virginia. California officials extradited him to Virginia.
The execution would be the first in Virginia since January 2013. The state has carried out 110 executions since the U.S. Supreme Court reinstated the death penalty in 1976.
The courts' rulings came as Oklahoma's attorney general sought to stay three executions to examine the cause of a mix-up with its lethal drugs.
