Alabama carried out its third execution this year using the controversial new method of nitrogen gas, a technique that in previous state killings caused visible signs of distress.
Carey Dale Grayson was put to death on Thursday evening for the 1994 murder of a hitchhiker. The prisoner had a mask strapped to his face through which nitrogen was pumped, causing fatal oxygen deprivation.
The US supreme court declined Grayson’s request for a stay on Thursday. His attorneys had argued that the nitrogen gas method should be further scrutinized before it was used again.
Alabama is the only state in the US to use nitrogen, which it has adopted in the face of international condemnation. Veterinarians in the US and across Europe have ruled out nitrogen as a form of animal euthanasia for most mammals, yet the state has turned to it in the wake of a spate of gruesomely botched lethal injection executions.
“The only lesson from this grim sequence of events is that when states use human beings as guinea pigs for lethal experiments, they are bound to suffer, whether at the point of a needle or behind a mask,” said Matt Wells, deputy director of the human rights group Reprieve US.
The first two nitrogen executions conducted by the southern state did not proceed without controversy. Alabama insisted that the first nitrogen killing in January of Kenneth Smith was “perhaps the most humane method of execution ever devised”.
That claim conflicted with eyewitness accounts, which recorded that Smith writhed and convulsed on the gurney for several minutes, as his body shook and eyes rolled back.
Smith’s spiritual adviser, the Rev Jeff Hood, said that “what we saw was minutes of someone struggling for their life”.
In September, Alabama used nitrogen to kill Alan Miller. The prisoner shook and trembled on the gurney for about two minutes, followed by about six minutes of gasping, according to a witness from Associated Press.
Earlier this week, lawyers for Grayson, 50, argued before a federal appeals court that the experience of the first two executions suggested that nitrogen led to feelings in those condemned of “conscious suffocation” before unconsciousness set in. They said that amounted to the infliction of terror that was a violation both of state law and the US constitution.
The appeals court denied the request for a stay of execution.
Grayson was convicted of killing Vickie Deblieux. He was part of a group of four teenagers who picked her up as she was hitchhiking, then attacked and murdered her.
Of the four, only Grayson, who was 19 at the time, went on to face execution. The other three co-defendants were 18, and had their death sentences set aside by the US supreme court as part of a prohibition of the death penalty for juveniles.
