Alabama conducts fourth nitrogen execution in the U.S.

State corrections officers executed convicted murderer Demetrius Terrence Frazier on Thursday night, marking the fourth time the controversial execution method has been used. The 52-year-old inmate received the death sentence for the 1991 rape and murder of Pauline Brown in Birmingham, Ala. The state made history last year by performing the nation’s first nitrogen gas execution and has faced stiff opposition to the practice ever since.

Experts remain divided over how much pain a prisoner experiences while inhaling pure nitrogen. Some advocates maintain that the method is efficient and painless, while some critics characterize the method as cruel and unusual punishment they say should be unconstitutional under the Eighth Amendment. Witnesses to previous nitrogen executions described prisoners shaking and experiencing labored, sporadic breathing for minutes.

How did the execution go? Frazier apologized to the family and friends of Pauline and said the assault and murder should never have happened, according to reporting by the Associated Press. Officials allowed five representatives of the media, including one reporter from the Associated Press, to witness the execution. Technicians strapped Frazier to a gurney with a gas mask over his face, according to the Associated Press reporter. About two minutes after the gas began flowing, the prisoner grimaced and began quivering which progressed into gasping for air and lifting his legs several inches off the table, according to the report.

The gas flowed for about 18 minutes and Frazier's heart stopped beating after about 13 minutes, according to Alabama Corrections Commissioner John Hamm. Alabama enforces the law and justice was carried out for Pauline Brown and her family, Gov. Kay Ivey said after the execution. Rapists and murderers are not welcome in Alabama, and anyone who tries messing with an Alabama citizen won’t get away with it, she added.

Dig deeper: Read my report on Fraizer’s last-minute petition to be sedated before the execution.