MONTGOMERY, Ala. (AP) — Alabama has scheduled a second execution with nitrogen gas, months after the state became the first to put a person to death with the previously untested method.

Alabama Gov. Kay Ivey set a Sept. 26 execution date for Alan Eugene Miller, who was convicted of killing three men during a 1999 workplace shooting. The execution will be carried out by nitrogen gas, the governor’s office said. Miller survived a 2022 lethal injection attempt.

The governor’s action comes a week after the Alabama Supreme Court authorized the execution.

In January, Alabama used nitrogen gas to execute Kenneth Smith. Smith shook and convulsed in seizure-like movements for several minutes on a gurney as he was put to death Jan. 25.

A nitrogen hypoxia execution causes death by forcing the inmate to breathe pure nitrogen, depriving him or her of the oxygen needed to maintain bodily functions. Alabama and some other states have looked for new ways to execute inmates because the drugs used in lethal injections, the most common execution method in the United States, are increasingly difficult to find.

Miller has an ongoing federal lawsuit challenging the execution method as a violation of the constitutional ban on cruel and unusual punishment, citing witness descriptions of Smith’s death.

“Rather than address these failures, the State of Alabama has attempted to maintain secrecy and avoid public scrutiny, in part by misrepresenting what happened in this botched execution,” the lawyers wrote in the lawsuit. It is anticipated that his attorneys will ask a federal judge to block the execution from going forward.

Attorney General Steve Marshall maintained that Smith’s execution was “textbook” and said the state will seek to carry out more death sentences using nitrogen gas.

State attorneys added that Miller has been on death row since 2000 and that it is time to carry out his sentence.

Miller, a delivery truck driver, was convicted of killing Terry Jarvis, Lee Holdbrooks and Scott Yancy in the workplace shootings.