A Utah man who served two years in prison for breaking a child’s arm was charged last week with killing a 2-year-old boy and seriously injuring the child’s twin sister.

Jonathan Allen Dunn as been charged with aggravated murder, aggravated child abuse, and two counts of aggravated sexual abuse of a child, The Associated Press reported.

Dunn, 36, called 911 Thursday morning to say the boy, identified on a GoFundMe as Aleister, wasn’t breathing. But after his arrest, Dunn told officers he punched both children in the back, sides, and chest while babysitting them Wednesday night and that “he was hitting them harder than he should have.”

According to KSL, he shot both children with a Nerf gun and hit them several times with the butt ending of the guns and used a “mallet which he stated was made of hard foam” to hit the children in the back of the head multiple times.

He also said he pinched the children’s genitals and shoved them into a door frame then gave them Tylenol for the pain. He also gave Aleister cough medicine and his sister a children’s sleep aid.

In the morning, Dunn said, Aleister was wheezing so he gave him more cough medicine. Sometime between 8:30 and 9, the boy stopped breathing.

When officers arrived, Dunn had left Aleister lying on the front porch. The girl was on the couch in the living room, KSL said.

According to court records, both children had bruises all over their bodies. The girl was treated for a brain bleed at a hospital.

Police said that Dunn is a friend of the victims’ parents and that other children, not related to the twins, were in the home when the brutal assault took place. They were taken into protective custody.

“Jonathan Dunn severely injured two separate 2-year-old children in his care, killing one of them. He has multiple other children, including another 2-year-old in his home,” the affidavit said. “He has a prior conviction for a serious child abuse case where he broke another 2-year-old child’s arm and caused bruising to his face. He admitted that he lost control and his anger got the best of him and he caused these injuries to small children.”

Dunn was sentenced in May 2017 for breaking the arm of a child in his care in 2016, the AP said. He was released from prison in April 2019 and was on parole until December 2021.

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[Featured image: Jonathan Dunn/Cache County Sheriff’s Office and Aleister/GoFundMe]