Doerman, 33, was sentenced to three consecutive life terms in Clermont County, Ohio, last week after he pleaded guilty to aggravated murder charges.
He also received a 16-year sentence for two felonious assault charges against his former wife and stepdaughter.
Prosecutor Mark Tekulve previously said he would seek the death penalty for the brutal slayings that took place on June 15, 2023, in Monroe township, 120km west of Columbus.
The Associated Press reported that he instead pursued the life sentences to spare further “agony” for family members after the trauma they experienced after the murders of Clayton Doerman, 7, Hunter Doerman, 4, and Chase Doerman, 3
“My job, as I saw it this week, was to relieve them of that additional agony,” he told media last week.
The boys’ mother, Laura Doerman, admitted to the the court that the plea deal she approved would surprise some but delivered “finality to the court case for my daughter and me”.
Tekulve this week revealed more details of what led to the murders, briefing media on Chad Doerman’s behaviour before the killings, and told of the heartbreaking moment he turned a gun on his own family.
He said Doerman searched online for a song called Happy in Hell by Colt Ford on the morning of the killings, showing the lyrics to the song’s chorus, the Daily Mail reported.
“I’m in a catch twenty-two/ Damned if I don’t damned if I do/ I’m in love with another girl/ And I’ve been dreamin’ in another world/ I’ve been livin’ with the devil/ While I’m creepin’ with an angel/ All’s well that ends well/ I guess I’ll be happy in hell.”
He then called his father around midday and said that “Clayton is going to be the hardest one”.
The prosecutor said that Doerman’s father only realised the significance his son’s reference to his eldest boy after the killings.
Chad Doerman with the three sons he executed in cold blood.
Doerman’s disturbing comments to family continued as his told wife Laura “this will be my last good meal” as the pair ate lunch.
“At 3.30, 3.45pm, he begins to read the Bible to Hunter. He’s walking around the house with the Bible mumbling ‘Chad knows what’s right, Chad knows what’s right’,” Tekulve told reporters.
He opened the home’s gun safe at 4pm, saying he was “just playing around” after his wife said his action were scaring her.
“He did this to again allay any concerns about her safety, his safety, or the safety of the boys. He actively deceived her,” Tekulve said.
Doerman went on to tell his sons that he “loves them and they did nothing wrong” and they were “the best boys ever”.
He then chased Clayton through the home before executing him and his stepdaughter tried to protect her little brother Chase by picking him up.
A ring camera at the home captured the teenage girl telling Doerman: “Please don’t shoot me” before he forced her at gunpoint to put her little brother down.
The preschooler then ran for his life as his father reloaded his gun.
In a last desperate bid to protect her child, Laura Doerman then placed her finger over the barrel of the weapon but her husband fired anyway, injuring his wife before turning his attention back to his little boy and executing him in front of his mother.
