Crime Missouri Man Killed 4-Year-Old Girl by Beating, Dunking Her in Icy Pond as Part of 'Religious-Type Episode' Ethan Mast pleaded guilty Tuesday to murder of a neighbor's 4-year-old child after allegedly calling her mother a 'demon' By Jeff Truesdell Published on February 25, 2022 03:47PM EST Share Tweet Pin Email Ethan Joel Mast. Photo: AP/Shutterstock A Missouri man has pleaded guilty to the murder of a 4-year-old girl who was beaten with a belt and then dunked in an icy pond in what the local sheriff has described as part of a "religious-type episode." At the time of the man's December 2020 arrest, Benton County Sheriff Eric Knox said the accused had described the deceased girl's mother, who was a neighbor, as a "demon," and claimed the child would end up like her mother unless someone intervened. The man, Ethan Mast, and another neighbor, Kourtney Aumen, both were charged with second-degree murder as well as three counts of first-degree assault and single counts of first-degree sexual abuse with physical harm. Neighbors Charged After Allegedly Beating 4-Year-Old Girl to Death, Torturing Her Family Mast, 36, pleaded guilty Tuesday to the second-degree murder charge and could face life in prison, reports KY3. PEOPLE confirms through online court records that his plea was the result of a plea agreement. Aumen remains in the Benton County jail with no bond, according to jail records. She has pleaded not guilty. Police were summoned by the slain girl's father to a residence in Cole Camp shortly after 1 a.m. on Dec. 20, 2020. The father alleged that his neighbors, Mast and Aumen, had tortured and beaten his young daughter and toddler son over several days, according to a sheriff's office news release. He further alleged that he and his wife also were tortured. Parents of 4-Year-Old Girl Who Was Allegedly Killed by Neighbors Are Charged With Child Endangerment The man allegedly told police his "daughter had been beaten" with a leather belt and then "submerged in a pond" before being "left to freeze on the bank before being taken back into the residence." When deputies arrived, the 4-year-old girl, later identified as Jessica Mast, was dead. Her body was found wrapped in a blanket on a bedroom floor, and her entire body showed "severe purple bruising" and ruptured blisters, the Associated Press reported. "Based on what I know, I think this could be some kind of honest-to-goodness religious-type episode," Benton County Sheriff Eric Knox told AP at the time. The two suspects and the victimized family all belonged to the same church, but Knox declined to name the church or its denomination. Knox could not immediately be reached by PEOPLE for comment on Friday. Want to keep up with the latest crime coverage? Sign up for PEOPLE's free True Crime newsletter for breaking crime news, ongoing trial coverage and details of intriguing unsolved cases. Days after the arrests of Mast and Aumen, police also arrested the girl's mother, Mary Mast, and father, James Mast, on charges of endangering the welfare of a child in the first degree resulting in death. Mary Mast also was charged with domestic assault in the first degree, the sheriff's office said in a news release. An additional charge against James alleged he endangered the welfare of a child in the first degree resulting in serious physical injury. After the parents' arrest, the sheriff said in the news release that his office received many calls claiming that 4 year old's "death and the surrounding circumstances" were the "actions of a cult" and that "there have been some references to God and demons." He added: "None of the actions contained in this case are condoned by the church they attended. The investigation done so far indicates that this is an isolated incident and NOT the actions of a cult." James and Mary Mast both have entered pleas of not guilty and been released on bond.