Alabama put to death convicted murderer Kenneth Smith on Thursday evening, Governor Kay Ivey said, completing the first execution using asphyxiation by nitrogen gas, which the state is advancing as a simpler alternative to lethal injections.
The state has called its new protocol “the most painless and humane method of execution known to man”.
United Nations human rights experts and lawyers for Smith, who survived Alabama’s previous botched attempt to execute him by lethal injection, had sought to prevent it, saying the method was risky, experimental and could lead to a torturous death or non-fatal injury.
Alabama prison officials and journalists who observed Smith’s execution were due to brief reporters later on Thursday evening.
Smith, convicted of a 1988 murder-for-hire, was a rare prisoner who has already survived one execution attempt.