WARNING: DISTRESSING CONTENT
The neighbour of killer dad Chris Watts has been praised for warning police he "wasn't acting right" in the hours after he murdered his entire family and helping solve the case.
Watts strangled and smothered his pregnant wife Shanann, 34, to death, before strangling their daughters Bella, 4, and Celeste, 3, with a blanket in 2018.
He buried his wife – who was carrying their unborn son, Nico – in a shallow grave on a remote oil field that was owned by his employer at the time and dumped his daughter's bodies in an oil tank.
The 34-year-old from Colorado is currently serving five life sentences in Wisconsin Prison for the murders.
Now a new Netflix documentary has been released, airing new details about the horrific case and revealing how an unnamed neighbour raised suspicions about Watts' just hours after the family were reported missing.
Police footage was shown from the moment officers showed up to the house after receiving a request from Shanann's friend to perform a welfare check.
After initially finding no one home, Watts turned up and appeared panicked and flustered as he answered police questions and showed them around the home.
During the visit, the neighbour offered to show a police officer footage from his home security cameras.
"If there is any sort of action out there, I would have got it," the unnamed man said.
Watts was present when the neighbour played his CCTV footage which showed him moving his car on his driveway at 5.17am and tried to explain the bizarre behaviour.
After the exchange, the policeman spoke to the neighbour alone, at which point he said: "He's not acting right at all. He's never fidgety."
"He's never rocking back and forth, and if you look," he said, motioning to his backlog of security recordings, "he never loads his stuff in and out of the garage ever".
The neighbour went on to flag other suspicious things he'd noticed, from the fact he's normally "quiet" and "really subdued".
"He never talks, so the fact he's over there blabbing his mouth makes me kinda suspicious of something," he said.
The neighbour turned out to be right.
It emerged the CCTV footage had actually captured Watts loading the bodies of his pregnant wife along with his two daughters into his truck, before dumping them at a work site.
He confessed to the killings three days later.
Social media users have praised the neighbour after watching American Murder: The Family Next Door. Many said he "solved the case in five minutes".
"That vigilant neighbour knew Chris Watts was guilty from the get go, and really nailed him," one person wrote.
"Interesting how the neighbour knew immediately that Chris Watts was guilty based on behavioural changes," another said.
"Shoutout to Chris Watts's neighbour in the documentary. That dude was on it," someone else added.
The doco also revealed the final texts Watts sent his wife on the day he killed her and their children.
"What kind of vegetables do you want with dinner tonight?" Shanann texted Watts.
"Broccoli works," he responded. "Green beans work, too."
Watts initially denied any wrongdoing, even going on live TV shortly after burying their bodies, begging anyone with information to come forward.
After admitting to the murders, Watts claimed had it not been for his mistress Nichol "Nikki" Kessinger – a fellow employee at his work – he would not have killed his family.
Author Cheryln Cadle, who is behind the book Letters From Christopher, said Watts was "mesmerised" by his mistress.
"She showed him respect that he didn't feel like he'd ever been shown before," Cadle said in an interview with the Daily Mail.
She said Watts was so enamoured with Kessinger that when she told him she wanted to "give him his first son", he allegedly tried to cause his wife to miscarry by giving her a strong painkiller.
Kessinger spoke about the case for the first time in an interview with The Denver Post on November 15 where she said she was tricked into believing Watts was a loving father, finalising a divorce and she had no idea his wife was 15 weeks' pregnant.
"He lied about everything," Kessinger, 30, told the publication.
• American Murder: The Family Next Door is streaming on Netflix now.