MONTGOMERY, Ala. (AP) — Some say inhaling nitrogen gas would be like dying on a plane that depressurizes in flight, swiftly killing all aboard. Now more than a quarter of Alabama's death row inmates have signed statements saying they would prefer that gas over lethal injection or the electric chair when facing execution.

No inmate in the U.S. has been put to death with nitrogen gas before, and critics suspect at least some inmates are simply hoping to delay a date with the death chamber through the inevitable legal challenges ahead.

State corrections officials say 51 of Alabama's 180 inmates h...