A full review has been ordered into the execution of double murderer Joseph Wood, who took two hours to die after being given a lethal injection.
Arizona's Governor Jan Brewer said that while justice had been done she was concerned by how long the lethal injection procedure took.
She said: "One thing is certain, however, inmate Wood died in a lawful manner and by eyewitness and medical accounts he did not suffer.
"This is in stark comparison to the gruesome, vicious suffering that he inflicted on his two victims, and the lifetime of suffering he has caused their family."
More top news
Freezing temperatures, a biting wind and risk of snow into next week
Austerity and Brexit are dividing Britons and causing a "schism" in society, the Archbishop of Canterbury has warned.
A taxi driver has been suspended after inspectors found he was using a Costa Coffee lid as a fuel cap.