The US state of Oklahoma executed a second inmate Thursday by administering a new drug that has sparked controversy over suffering the condemned may suffer while dying.
Kenneth Hogan, 52, was put to death in the southwestern state. He was declared dead at 6:30 (0030 GMT Friday) at McAlester prison, spokesman Jerry Massie told AFP.
Hogan received a mix of drugs that included a lethal dose of pentobarbital, an anesthetic commonly used to euthanize animals that the state acquired from a compounding pharmacy unregulated at the federal level.
Earlier this month, the state used the cocktail for the first time to put to death Michael Lee Wilson, who said he could feel his "whole body burning" as the injection took effect.
Hogan, who had spent 27 years on death row, also reacted to the chemicals in his final moments.
"There is a chemical taste in my mouth," he said after receiving the injection.
"I am going, I am going, I am going."
In his final statement, he also declared: "I am guilty for what I am here for and I take full responsibility for my action."
Ohio inmate Dennis McGuire, put to death on January 16 with a different, untested mix of drugs, struggled and gasped for air for at least 10 minutes in an unusually prolonged execution, according to witnesses.
Facing diminishing stocks of the drugs previously used in lethal injections after European drugmakers refused to supply substances to be used in human executions, a number of US states have sought new means of carrying out their executions.
But controversy has erupted over the changes in protocol, including objections to the untested nature of the new cocktails and to the lack of federal oversight to the compounding pharmacies that supply them.
Opponents to the new lethal injection cocktails say using essentially experimental procedures on inmates could cause undue suffering and violates the constitutional amendment against cruel and unusual punishment.
And they have raised concern over the compounding pharmacies, which are only regulated by local and not federal laws. Their products are not approved by the Federal Drug Administration.
A scandal erupted in November 2012 in Massachusetts when poor hygiene at one of these pharmacies was blamed as the cause of a deadly meningitis outbreak.
Hogan was sentenced to die for the 1988 stabbing murder of a woman with whom he had just smoked marijuana.
His execution was the fifth of 2014 in the United States. It marked the second in Oklahoma, a state that has carried out 110 of the 1,364 death penalties since the US reinstated capital punishment in 1976.