A serial rapist and murderer is to be put to death by nitrogen gas in Alabama, the fourth use of the controversial execution method in the southern state.

Prosecutors said on Nov. 27, 1991, that Frazier, then 19, broke into Brown’s apartment through a window while she was asleep. Prosecutors said he demanded money and raped Brown at gunpoint after she gave him $80 from her purse. He then shot her in the head. He later returned to the apartment to have a snack and look for money, prosecutors said.

The execution is set for 6:00 pm Central Time (0000 GMT) at a prison in Atmore, Alabama. The process will involve pumping nitrogen gas into a facemask, leading to suffocation. Alabama has already carried out three executions by this method last year.

A serial rapist and murderer is to be put to death by nitrogen gas in Alabama on Thursday, the fourth use of the controversial execution method in the southern US state. Alabama carried out three executions by nitrogen asphyxiation last year and is the only US state currently using the method.