Oklahoma inmate Clayton Lockett apparently called out during his execution, saying "something's wrong", an Associated Press reporter on the scene has said.
Lockett later died of a heart attack, but the execution of fellow inmate Charles Warner has been postponed for 14 days.
Prison director called the execution because Lockett was still moving. At 6:37 Lockett, still moving, said "somthing's wrong."
He was conscious and blinking, licking his lips even after the process began. He then began to seize.
More top news
The Foreign Secretary was unable to rule out the possibility of continuing to pay money into the EU when he spoke to Peston On Sunday.
He told Peston on Sunday: "The country is crying out for leadership from the Prime Minister. We want to know her vision."
All the profits from the sale of each download of the forthcoming single would go to Shooting Star Chase and Together for Short Lives.