WASHINGTON - The US state of Oklahoma executed a death row inmate Thursday, the first since a botched execution that forced a halt on killings eight months ago.
Charles Warner, 47, was declared dead by lethal injection at 7:28 pm (0128 GMT Friday), just over an hour after the Supreme Court rejected his last-minute appeal for clemency, spokesman for Oklahoma prisons Jerry Massie told AFP.
Warner was supposed to be killed on Apr 29 after the execution of another inmate, Clayton Lockett.
But Warner's execution was delayed after the bungled killing of Lockett, who took 43 minutes to die instead of the expected 10 minutes.
At Lockett's execution, he was seen writhing in pain, bucking off the gurney and mumbling unintelligibly.
The central state of Oklahoma had paused executions after the incident, which renewed fierce debate over the death penalty in the United States.
Warner was sentenced to death for the rape and murder of his girlfriend's 11-month-old baby.
Five out of nine justices at the top US court voted in favour of moving ahead with Warner's execution Thursday.
The dissenting opinion from the four other justices said the method of lethal injection should be examined and "warrants this court's attention." Warner and three other Oklahoma death row inmates have asked the court to consider the constitutionality of lethal injections containing the drug midazolam, an anesthetic which has been criticised as causing three particularly lengthy and apparently painful executions.
The inmates said midazolam, which was used in executions in Ohio in January, Arizona in July and Lockett's in April, had caused inmates to show signs of suffocation, choking and suffering before dying 26 to 117 minutes later.
Warner's attorney Dale Baich urged the court to consider the issue and argued against the drugs used in executions by lethal injection.
"At some point in the near future, the court will have to revisit the issue of lethal injection," said Baich, attorney for Warner and other Oklahoma death row prisoners.
"The drugs and drug combinations used in executions today vary tremendously across different jurisdictions. This experimentation has led to the predictable, but tragic result of multiple botched executions." In 2008, the Supreme Court ruled that lethal injections were allowed under the US Constitution. But since then, the majority of states have changed their drug protocols, due to a shortage of the old standards.