Alabama executes man with nitrogen gas using new method for the first time

Officials said Kenneth Eugene Smith, 58, was pronounced dead at 8.25pm at an Alabama prison after breathing pure nitrogen gas through a face mask to cause oxygen deprivation. File picture: Alabama Department of Corrections via AP

Alabama executed a convicted murderer with nitrogen gas on Thursday, putting him to death with a new method that once again put the US at the forefront of the debate over capital punishment.

The state said the method would be humane, but critics called it cruel and experimental.