The state could use a new method of execution on an inmate whose death sentence is scheduled for this month.

Alan Eugene Miller, 57, is on death row at William C. Holman Correctional Facility in Atmore for the 1999 shooting of three men during a workplace rampage in Shelby County. He is set to be put to death Sept. 22 via lethal injection.

However, the state may be prepared to use an alternative method called nitrogen hypoxia before then, deputy state attorney general James Houts told U.S. District Judge R. Austin Huffaker Jr.

In the event that the method is used, the prisoner would experience asphyxiation by breathing pure nitrogen to replace the oxygen in his body.

The execution method has been authorized by Alabama and two other states but never utilized, according to the Associated Press. Alabama Department of Corrections Commissioner John Hamm will make the final decision regarding the alternative method.

Miller, who desires to be executed by nitrogen rather than lethal injection, filed suit against the state claiming correctional staff lost his paperwork requesting his preferred method of death.

AP reports that the state asked Miller to be fitted for a mask for the use of nitrogen, but he declined. The lawsuit aims to block the execution from being carried out until Miller’s lawyers collect more information concerning the nitrogen hypoxia process.

Miller is set to become the 224th inmate put to death by the state.

Dylan Smith is the editor of Yellowhammer News. You can follow him on Twitter @DylanSmithAL