He helped beat a child during an exorcism that caused the 4-year-old's death. Now, he faces decades behind bars.

One of the people who allegedly killed a child during an exorcism admitted to his crimes and now faces decades in prison, according to reports.

Last month, Ethan Mast pleaded guilty to second-degree murder and felony assault, according to KSHB. He is set to be sentenced at a later date.

Mast was arrested along with Kourtney Aumen and the victim’s parents, James and Mary Mast, in connection to the death of the 4-year-old girl. Ethan Mast is not believed to be related to the other Masts.

The criminal cases against all the defendants except for Ethan Mast remain active.

On Dec. 20, 2020, the child was found dead in Benton County, Missouri, according to KOZL.

Police went to a home and spoke to James Mast and asked what happened. The child appeared to have several bruises from her neck to her feet that appeared to be belt marks. Another child also had injuries, as did Mary Mast.

James Mast said the people across the street — Aumen and Ethan Mast — caused the injuries, according to KOZL. James Mast said the beating had happened for about two weeks and James was also beaten with a wooden spoon.

“I asked how he could let people do this to his family, and he stated that they were told (the mother) had a ‘demon’ inside her, and her children would end up just like her if it was not taken care of,” police noted in court documents, according to KOZL.

James Mast also said Ethan Mast and Aumen threatened him and said if he or his wife provided aid to the children, it would be a sin and Satan would come, according to the report. Some assaults also happened in a pond.

Ethan Mast and Aumen told the family they were beating the demons out of the victims.

Benton County Sheriff Eric Knox told KOZL at the time of the arrests that he could only speculate the death was the result of “skewed religious ideas.”

“Law enforcement is based on facts, and the facts are that we have are that the little girl died at the hands of Ethan and Kourtney and mom and dad stood by and watched it happened, as well as mom actually participated in some of it and she’s charged according to Missouri state statutes,” Knox said, according to KOZL.