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
Nobody knows what the outcome of tomorrow's election will be - but it's clear the winds of change are blowing hard, writes Tom Bradby.
Ukip party leaders have vowed to overhaul candidate vetting processes after a string of allegations emerged just days before the election.
ITV News is ready to bring you all the results and drama from the most exciting and unpredictable general election night in a generation.