In 1996, a jury recommended 11-1 that Kenneth Smith be sentenced to life without the possibility of parole for his role in a murder-for-hire plot. The judge overruled the jury and imposed a death sentence, a practice that is no longer legal. Now, nearly three decades later, the state of Alabama plans to use Smith as a test subject for a new execution method: death by inhaling nitrogen gas.

The states decision to execute Smith by nitrogen hypoxia on Thursday forcing him to breathe only nitrogen through a mask while depriving him of oxygen comes after a failed attempt to kill him by lethal injection in November 2022. Although Alabama is one of three states that has authorized executions using nitrogen gas, no state or the federal government has actually carried out such an execution.

Alabama switched its planned killing method in Smiths case after he fought in court to block the state from attempting to kill him again through lethal injection. In addition to Smith, Alabama has failed to kill two other people it tried to execute with lethal injection in recent years. In a fourth lethal injection execution, the killing took more than three hours. Even in lethal injection executions with no observable problems, autopsies of the deceased show signs of pulmonary edema, a condition where the lungs fill with fluid and create the painful sensation of suffocating or drowning.

Despite the clear problems with lethal injection executions, there is no evidence that executions using nitrogen would be any more humane. A botched nitrogen execution could lead to a slow, painful death by asphyxiation or even leave the individual alive but in a persistent vegetative state, according to medical experts. Alabamas plan to supply nitrogen through a mask worn by Smith also poses a risk to others in the execution chamber, including Smiths spiritual adviser, Rev. Jeff Hood.

This is the most inept, unqualified, unprofessional execution squad in the country. And they think theyre going to be the ones to do this nitrogen hypoxia without a hitch? Hood said in an interview. Kenny is facing a torture of uncertainty throughout all of this. I think it is as cruel and unusual as any punishment in human history.

Smith, who along with his lawyers did not respond to a request for comment, previously told NPR that he is terrified by the prospect of being killed with nitrogen gas.

Ive been doing time for 35 years now, and Ive tried to place myself in my brothers shoes when theyre around the corner and going through this. But nothing prepares you for it, Smith said. The anxiety and stuff starts building up before you ever get your date. And now that youre approaching that time, the anxiety starts to build. And, yeah, there is a mental trauma there that I never realized until I went through that.