The US state of Alabama Thursday used for the second time the controversial nitrogen gas asphyxiation method to put down death row inmate Alan Eugene Miller for the 1999 killing of three co workers. While supporters of this mechanism claim that the person being executed loses consciousness quickly, which makes it more humane than other execution methods, others contend that nitrogen could lead to excessive pain and torture and that there is no way of knowing with certainty at which point a person loses consciousness when exposed to 100% nitrogen. Miller was pronounced dead at 6.38 pm local time at Atmore prison.