Officials in the US state of Oklahoma have executed a convicted murderer using a drug that is typically used to euthanise animals.
John David Duty (58) was pronounced dead at 6.18pm local time, Department of Corrections spokesman Jerry Massie confirmed by telephone from Mcalester, Oklahoma.
Mr Massie said a three-drug cocktail was administered, including pentobarbital, a drug used in euthanasia of animals as well as a sedative for humans. He said it was its first use in a US execution and replaced sodium thiopental, a sedative that was in short supply.
"There were no apparent issues" with the new drug, Mr Massie said. A federal court in Oklahoma ruled the drug could be used in the execution, a ruling later upheld by the 10th US Circuit Court of Appeals.
Duty was convicted of murdering his cellmate, Curtis Wise, with a bedsheet in 2001.
Prison officials said Duty's last words were: "To the family of Curtis Wise, I would like to make my apology. One day you will be able to forgive me, not for my sake but for your own. My family and friends are here too. You've all been a blessing. Thank you Lord Jesus. I am ready to go home."
Duty was serving two concurrent life sentences for robbery, shooting with intent to kill, and rape, when he murdered Mr Wise. Duty convinced Mr Wise to pose as a hostage to entice guards to move Duty to a different cell. After binding Mr Wise's hand and foot, Duty strangled him.
Duty then wrote a letter to his victim's mother bragging about the murder.
His execution was the third this year in Oklahoma and the 46th in the United States.