Video footage has been released of the moment Chris Watts returned home from dumping his wife and daughters' bodies to find police at his door.
Nickole Atkinson, the best friend of his wife Shanann, whose body Watts had dumped in a shallow grave, was also with police as she filed a missing person's report after failing to get in touch with the pregnant mum-of-two.
The video, obtained by news.com.au, was taken from bodycam footage of the responding officer from the Frederick Police Department.
Even though Watts barely acknowledges Ms Atkinson as police search the house, the nervous-looking triple-killer can be seen glaring at Ms Atkinson on multiple occasions.
She is seen making phone calls to friends and family members of Shanann, while also searching for clues as Watts stands by aloof.
But her stress escalates after realising Shanann's medication is still at the home.
He had taken his two girls Bella, 4, and Celeste, 3, to a birthday party just 24 hours prior. He had even fed them pizza and got them each a snack before putting them to bed.
Hours later, the girls and their mother Shanann were all murdered in the house. Shanann's body was disposed in a shallow grave and his daughters in an oil tank.
Watts, who had started an affair with a co-worker, told Shanann they were "not compatible", he had fallen out of love and he resented her need for organisation and control.
"Shanann wanted to change to help her marriage," friends told police. "She wanted to work on that."
But it was already too late. Watts was making plans to move to an apartment, exchanging explicit photos with his new girlfriend and had told her he loved her.
The affair with Nichol Kessinger, 30, began around the time he learnt his wife was pregnant in June. Almost immediately, his wife noticed something had changed.
However, before she left for a weekend work trip in Arizona for her sales job, Shanann told friends he had given her signs there might be a resolution. But on the Saturday night, she noticed a $60 credit card bill from a restaurant.
After confronting Watts to ask what he was doing, he claimed he had bought salmon and a beer while out to see a game with friends. But it wasn't the case, he was out with his mistress, while a babysitter cared for the children.
Shanann was dropped off at home by her friend, Ms Atkinson, just before 2am on Monday, August 13, and it's at this point that there's a gap in the timeline.
Footage from 5.30am shows Watts backing his work truck up to the garage before driving off, something the family's friends agreed was unusual.
Police believe that at some point during this window he viciously killed his wife and children, before driving the bodies to the site of the oil and gas company where he worked.
Watts spent a normal day at work and frequently texted his girlfriend Ms Kessinger, even as police began investigating his family's disappearance.
He made calls to a real estate agent about selling the family home and told the girls' school that they would not enrol that autumn as planned.
Within days, he was charged with killing his family.
Originally, Watts faced the possibility of the death penalty or life in prison without parole.
But with the agreement of Shanann's family, the death penalty was eliminated from consideration in exchange for pleading guilty.
At his sentencing, Shanann's father, Frank Rzucek, called him a "heartless monster".