Alabama attorney general says he believes more nitrogen gas executions will take place after first in US carried out

The Alabama attorney general says he believes more nitrogen gas executions will occur after Kenneth Smith became the first person in the U.S. to be executed that way.

The Alabama attorney general said Friday that nitrogen gas is now a "proven" method of execution and that he believes more such executions will follow after the first one in the U.S. was carried out.

The inmate, Kenneth Smith, 58, was pronounced dead at 9:25 p.m. ET Thursday at the William C. Holman Correctional Facility in Atmore, Alabama – about 120 miles southwest of Montgomery – after the U.S. Supreme Court rejected a last-minute effort to halt the execution.

"What occurred last night was textbook," Attorney General Steve Marshall said during Friday's press conference. "And I now suspect that many states will follow. As of last night, nitrogen hypoxia as a means of execution is no longer an untested method. It is a proven one. It's the method that Kenny Smith ultimately chose."

Nitrogen hypoxia is the term for when enough nitrogen gas is inhaled that it deprives the body of oxygen – in this instance, intentionally so, as a means of execution.