Ohio prosecutors have leveled a slew of new charges against Chad Doerman, the 32-year-old man whom deputies found sitting calmly on his front porch next to a rifle after he allegedly executed his three young sons in broad daylight "in cold blood."

Clermont County Sheriff's deputies arrested Doerman on three charges of aggravated murder on June 15, but prosecutors said he also injured the boys' mother in the shooting spree. The new charges include kidnapping and assault.

"He was their world, he was their guardian, and he executed them in cold blood," Clermont County prosecutor David Gast said at the arraignment last week.

HARROWING 911 AUDIO REVEALS DAUGHTER'S PANIC OVER OHIO DAD ‘KILLING EVERYBODY’ IN 3 SONS' MURDERS

Clermont, Ohio deputy takes Chad Doerman into custody

A Clermont County Sheriff's Deputy takes Ohio dad Chad Doerman into custody after the 32-year-old allegedly gunned down his three young sons. Authorities used the black box on the left of the image to cover the body of one of the children before releasing bodycam video of the arrest. (Clermont County Sheriff's Office)

Shocking bodycam video shows Doerman chatting calmly with deputies, with bloodstains on his arm and shoulder, claiming "I ain't gonna hurt ya. I ain't gonna hurt nobody" – in stark contrast with 911 calls from two witnesses.

LISTEN: 911 audio reveals panicked daughter who survived Ohio dad allegedly shooting 3 sons

OHIO MAN ACCUSED OF EXECUTING 3 YOUNG SONS SEEN IN BODYCAM VIDEO SITTING CALMLY NEXT TO GUN AFTERWARD

One woman told dispatch she found a teenage girl running down the street calling for help, claiming Doerman was "killing everybody in her family."

"She said that her stepfather is killing everybody in her house," the woman told the dispatcher. "I asked her to get in the car with me, and she said she couldn't leave her family."

This undated photo released by the Clermont County Sheriff's Office shows Chad Doerman in a blue jail shirt during his mug shot

This undated photo released by the Clermont County Sheriff's Office shows Chad Doerman. Doerman, who is accused of fatally shooting his three young sons on Thursday, June 15, 2023, in Monroe Township, Ohio, admitted to planning the killings and lined them up before executing them with a rifle, prosecutors said. (Clermont County Sheriff's Office via AP)

According to a 21-count indictment, Doerman gunned down the boys, ages 3, 4 and 7, with a Marlin Model HC .22 rifle.

He is accused of executing two of his sons before he "hunted" down the third, who had fled into a neighbor's field, only to drag him home and shoot him too. 

OHIO MAN ADMITS TO LINING UP 3 YOUNG SONS IN YARD, EXECUTING THEM WITH RIFLE: PROSECUTORS

Ohio dad Chad Doerman sitting on stoop with rifle at his side as a responding officer approaches gun drawn

Chad Doerman was found sitting on the porch next to his rifle when deputies arrived after the shooting deaths of his three sons, ages 3, 4 and 7, bodycam video shows. Court documents identified the suspected murder weapon as a Marlin Model HC .22 rifle. (Clermont County Sheriff's Office)

Although he ignored commands from responding deputies, they placed him in handcuffs without further violence.

In the bodycam video, black bars obscured the screen where the boys' bodies were laying on the grass. Immediately after Doerman was in cuffs, deputies attempted to render aid.

"This is by far the most sickening, horrifying crime I have seen," Clermont County Prosecutor Mark Tekulve said, according to the Cincinnati-based WKRC-TV. "I can only imagine the terror these little boys felt and experienced as their father – their protector – was murdering them."

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He is being held on $20 million bail and due back in court on June 26.

Fox News' Haley Chi-Sing and The Associated Press contributed to this report.