First nitrogen gas execution on death row leaves Alabama man "convulsing" for minutes

The first execution using nitrogen gas caused a man to shake and convulse for minutes on the gurney.

Breathing through a nitrogen-filled face mask that deprived him of oxygen, 58-year-old convicted killer Kenneth Eugene Smith convulsed in seizure-like spasms for at least two minutes of the 22-minute execution by nitrogen hypoxia on Thursday.

The force of his movements at times caused the gurney to visibly shake. That was followed by several minutes of gasping breathing until his breath was no longer perceptible. Smith’s supporters expressed alarm at how the execution played out, saying it was the antithesis of the state’s promise of a quick and painless death. But Alabama’s attorney general characterised the execution as "textbook" during a news conference.

"As of last night, nitrogen hypoxia as a means of execution is no longer an untested method. It is a proven one," Alabama attorney general Steve Marshall said, extending an offer of help for states considering adopting the method.

Asked about Smith’s shaking and convulsing on the gurney, Alabama corrections commissioner John Q Hamm said they appeared to be involuntary movements. "That was all expected and was in the side effects that we’ve seen or researched on nitrogen hypoxia," Mr Hamm said. "Nothing was out of the ordinary from what we were expecting."

Mr Marshall said he anticipated Alabama "will definitely have more nitrogen hypoxia executions".

More than 40 death row inmates have selected nitrogen as their preferred execution method over lethal injection but did so at a time when the state had not developed nitrogen procedures. Lawyers for those inmates have asked the court to order Alabama to turn over records and information about Smith’s execution.