Alabama's attorney general, Steve Marshall, declared the execution as "textbook" during a news conference held on Friday.

Smith had specifically requested nitrogen hypoxia as the method of execution after surviving a botched lethal injection in 2022. However, his attorneys argued that he was being used as a "test subject," while human rights activists criticized the untried nature of the new approach. Despite multiple legal challenges, the Supreme Court ruled on Wednesday that Alabama was within its constitutional rights to proceed with the execution.

The execution took place on Thursday night and marked the first time nitrogen hypoxia has been utilized to carry out a death sentence. Marshall emphasized that the successful implementation of this method has proven its credibility. He stated, "As of last night, nitrogen hypoxia as a means of execution is no longer an untested method. It is a proven one."

Smith was convicted of the murder of Elizabeth Sennett in 1989. He and another individual received $1,000 from Sennett's husband to carry out the crime. Shockingly, Sennett's husband later committed suicide, just a week after the killing. Smith's accomplice, Parker, was executed in 2010 for his role in the murders, according to the Alabama Department of Corrections.

Expressing his remorse, Marshall apologized to the couple's sons, Mike and Chuck, for the horrific manner in which their mother lost her life and for the significant delay in carrying out the sentence. He acknowledged the injustices caused by the prolonged process and sought to offer some solace to the grieving family.

Marshall also revealed that 43 other inmates on death row in Alabama have requested to be executed via nitrogen hypoxia. Moreover, he believes that other states will soon follow suit in adopting this method. Encouraging other states to consider nitrogen hypoxia, Marshall expressed his readiness to support them in implementing the process, saying, "Alabama has done it, and now so can you. We stand ready to assist you in implementing this method in your states."

The execution of Kenneth Eugene Smith using nitrogen hypoxia has served as a transformative moment in the history of capital punishment. As the debate surrounding the ethics and effectiveness of different execution methods continues, the success of this execution may set a precedent for other states considering alternative means of carrying out death sentences.