The US government carried out its first execution in 17 years on Tuesday, putting to death convicted murderer Daniel Lee over objections by his victims' relatives after the Supreme Court cleared the way with an overnight ruling.
Lee was pronounced dead at 8:07am EDT (1207 GMT), US Bureau of Prisons spokeswoman Kristie Breshears said by phone.
Lee's lawyers complained that they had received no notification of his rescheduled execution, while the nonprofit research group the Death Penalty Information Center said it appeared to be an "illegal, warrantless execution" because the execution warrant for Lee had expired at midnight.
Representatives of the Department of Justice and the department's Bureau of Prisons did not immediately respond to a request for comment.
The execution by lethal injection in Terre Haute, Indiana, had been held up by a US District Court in Washington, which on Monday ordered the US Justice Department to delay four executions scheduled for July and August. Lee's execution had previously been scheduled for 4 p.m. on Monday.
In issuing her injunction, Judge Tanya Chutkan had said Lee and other condemned men were likely to succeed in their legal challenge arguing that the single drug used in the lethal injection, the barbiturate pentobarbital, would cause an unconstitutional degree of pain and suffering.
Her order was later affirmed by an appellate court.
But at 2:10am (0610 GMT), the Supreme Court in a 5-4 vote cleared the way for federal executions to resume, ruling that Lee and other condemned men's challenges to the execution protocol did not justify "last-minute" intervention by federal courts.
"Last-minute stays like that issued this morning should be the extreme exception, not the norm," the Supreme Court wrote in its ruling.
Ruth Friedman, one of the public defenders who had represented Lee, rebuked the Department of Justice, saying it had not notified Lee's counsel of his execution.
In a statement, she said "it is beyond shameful that the government, in the end, carried out this execution in haste, in the middle of the night, while the country was sleeping. We hope that upon awakening, the country will be as outraged as we are."
Lee was convicted for his role in the killing of three members of an Arkansas family in 1996. But some relatives of his victims opposed him receiving the death sentence, while his accomplice in the murders, Chevie Kehoe, was sentenced to life in prison.
The victims' relatives unsuccessfully sued last week to delay the execution until the coronavirus pandemic had passed, saying they feared attending would risk their safety. The Bureau of Prisons later confirmed at least one member of its execution team had contracted Covid-19.
Strapped to a gurney before his death, Lee was asked if had any last words, according to a media witness present in the viewing chamber.
"I didn't do it. I've made a lot of mistakes in my life but I'm not a murderer," Lee said, according to a reporter who witnessed the execution and issued a report for all media. "You're killing an innocent man."
As the drug was being administered, Lee raised his head to look around, and his breathing appeared to become labored, according to the pool report. Soon after, Lee's chest was no longer moving, his lips turned blue and his fingers became ashy.
Two unnamed Bureau of Prisons officials and Lee's spiritual adviser could be seen inside the execution chamber.
While several states conduct executions, the federal government had not done so since 2003.
Attorney General William Barr announced last July that the Justice Department would resume carrying out executions of some of the 62 inmates on federal death row.
The Justice Department has scheduled two more executions of convicted child killers this week: Wesley Ira Purkey on Wednesday and Dustin Honken on Friday. An appeals court has temporarily stayed Purkey's execution date, and it remained unclear whether it would proceed.