Alabama murderer executed by nitrogen gas after burning man alive over $200 drug debt

The state of Alabama has carried out its latest execution using the controversial method of nitrogen gas, which causes four terrifying minutes of suffocation before death.

On Thursday evening, Anthony Todd Boyd became the seventh death row convict to die by nitrogen hypoxia in the state, with Alabama prison officials strapping him down and placing a mask over his face just hours after the US Supreme Court slammed the execution method for causing "intense psychological torment."

54-year-old Boyd had been found guilty and sentenced to death for his part in the brutal 1993 murder of Gregory Huguley in Talladega County, who was bound and burned alive over a minor $200 cocaine debt. By 6.33pm, October 23, he was pronounced dead by officials at William C. Holman Correctional Facility.

With his final words, Boyd continued to proclaim his innocence, saying: "I didn't kill anybody. I didn't participate in killing anybody." He added: "There can be no justice until we change this system," before saying his last three words before execution: "Let's get it."

Officials did not state when they began supplying nitrogen gas to Boyd, but reports from the facility indicate that he clenched his fist and began shaking, while lifting his head off the gurney, at around 5.57pm.

This ended after four minutes, but his struggle would continue for some time, making heaving breaths for a quarter of an hour before eventually lying still. The Associated Press reported that this appeared to take longer than previous nitrogen executions.

Alabama Governor Kay Ivey greeted the news of the execution, saying: "After 30 years on death row, Anthony Boyd's death sentence has been carried out, and his victim's family has finally received justice."

Boyd had always protested his innocence in relation to the 1993 murder, stating that he was at a party the night Mr Huguley was burned alive over a minor drug debt. Authorities do not believe that he set the fire, but that he was an accomplice to the horrifying crime.

At his trial, one of his fellow accused gave testimony after taking a plea deal, saying that Boyd had taped the man's feet together before another individual poured petrol on him and set him alight. The pair watched Huguley burn for up to 15 minutes, until the fire eventually subsided.

Boyd was convicted on a capital murder charge, with the jury deciding in a 10-2 vote that he receive the death penalty.

The man believed to have poured the petrol and set the fire, Shawn Ingram, was also convicted of capital murder and is also awaiting execution on Alabama's death row.

After exhausting his appeals and his execution date looming, the death row convict, fearing death by nitrogen gas, requested to be shot to death by firing squad.

A lawsuit filed by Boyd's attorneys states: "The administration of pure nitrogen gas causes the prisoner to experience the extreme pain and terror of suffocation while still conscious, inflicting gratuitous suffering beyond what is constitutionally permitted."

This argument was thrown out by a federal judge earlier this month, who ruled that "the Eighth Amendment (of the U.S. Constitution) does not guarantee Boyd a painless death" but instead a death without unnecessary suffering.

The state and federal denial of his request for a firing squad was backed by the right-leaning Supreme Court, with Justice Sonia Sotomayor writing a scathing dissenting opinion supported by two other judges.

Sotomayor pointed to the "mounting and unbroken evidence" that executions by nitrogen gas could be unconstitutional, violating the ban on "cruel and unusual" forms of punishment.

"Boyd asks for the barest form of mercy: to die by firing squad, which would kill him in seconds, rather than by a tortuous suffocation lasting up to four minutes," she wrote. "The Constitution would grant him that grace, my colleagues do not."