In a historic move, Alabama became the first state in the US to execute a death row inmate using nitrogen gas as the method. Kenneth Eugene Smith, 58, was pronounced dead at the William C Holman Correctional Facility in Atmore, Alabama, on Thursday. Smith had been convicted for his involvement in a murder-for-hire plot in 1988.

The use of nitrogen gas as a form of execution has been subject to intense scrutiny and controversy. Religious adviser Reverend Jeff Hood, who witnessed the execution, described a disturbing scene where Smith appeared to struggle for his life for a harrowing 22 minutes. Despite earlier assurances from Alabama authorities that the method would result in unconsciousness within seconds and death in minutes, witnesses reported seeing Smith conscious and visibly shaking on the gurney for several minutes.

The execution proceeded as planned, despite concerns raised by some. Smith's death came after the US Supreme Court declined a last-minute request to stay the execution. Justice Sonia Sotomayor expressed dissent, stating that the state had essentially used Smith as a "guinea pig" by employing an untested execution method.

Alabama Attorney General Steve Marshall addressed the controversy at a news conference on Friday, revealing that 43 more death row inmates in the state have chosen nitrogen hypoxia as their preferred method of execution. Currently, prisoners sentenced to death in Alabama have the option to choose between electrocution, lethal injection, or nitrogen hypoxia.

The use of nitrogen gas in capital punishment continues to spark debates around the ethical grounds and humaneness of execution methods. As more inmates in Alabama elect to die by nitrogen hypoxia, the controversial issue is likely to remain in the spotlight.