Alabama is planning to be the first place in the world to carry out an execution using nitrogen gas in January.

Kenneth Eugene Smith, 58, is set to die by nitrogen hypoxia—or suffocation on nitrogen gas—sometime between 2 a.m. on Thursday, January 25, and 6 a.m. on Friday, January 26.

Gov. Kay Ivey announced the time frame on Wednesday afternoon. The execution will take place at William C. Holman Correctional Facility in Atmore, which is the state’s only prison with an execution chamber.

The Alabama Supreme Court approved the Alabama Attorney General Office’s request for a death warrant last week.

Smith was twice convicted by juries for the murder-for-hire of Elizabeth Dorlene Sennett in her home in Colbert County in 1988. Sennett was a pastor’s wife who was beaten and stabbed. Smith confessed to his role in the crime and has been on death row since 1996.

The execution will be the first using nitrogen. The state Legislature approved the method of execution in 2018, and gave inmates one month to opt-in to changing their execution method from the default lethal injection to nitrogen hypoxia.

Inmates’ requests to die by the new method have been the subject of lawsuits for years.

“Elizabeth Sennett’s family has waited an unconscionable 35 years to see justice served,” Marshall wrote on X after the state’s highest court ordered the execution. “Though the wait has been far too long, I am grateful that our talented capital litigators have nearly gotten this case to the finish line,” he wrote.

Justices on the Alabama Supreme Court voted 6-2 to grant the death warrant, with one justice recusing themself from the case. Chief Justice Tom Parker and Justice Greg Cook dissented, but neither wrote an opinion.

Alabama’s redacted protocol for nitrogen hypoxia says the condemned inmate will be on a gurney and have a mask placed on his face. It says the nitrogen gas will be administered for 15 minutes or for five minutes following a flatline indication on the EKG, whichever is longer. The inmate will still have the opportunity to make a final statement after the death warrant is read and before the gas begins to flow.

The state tried to execute Smith by lethal injection in November 2022, but stopped the procedure because workers were unable to start an intravenous connection before the execution warrant expired at midnight. That longstanding rule was changed months later, allowing the governor to set a “time frame” for executions that could extend past 24 hours, doing away with the midnight expiration of death warrants.

In a federal lawsuit later, Smith had sought to block a second attempt to execute him by lethal injection, alleging it would subject him to cruel and unusual punishment. Smith claimed he was strapped to a gurney and poked with needles for several hours during the unsuccessful attempt to tap his veins.

Smith has said, even though he opted to die by nitrogen, he did not waive his right to challenge the new, untested method.

Read more: Former sheriff recalls woman’s ‘horrific’ murder-for-hire by pastor as Alabama prepares execution