Chris allegedly contended that he "went into a rage" and strangled wife Shanann after she killed their daughter, according to an arrest affidavit
Credit: Shanann Watts /Facebook

Under police questioning last week, Colorado triple murder suspect Chris Watts allegedly admitted he killed his pregnant wife, Shanann Watts, but only after, he claimed, he “went into a rage” when she strangled one of their daughters, court documents show.

Chris’ startling explanation for how his wife and their two children — 4-year-old Bella and 3-year-old Celeste — all ended up dead was revealed in a newly unsealed affidavit supporting his arrest.

The court document, obtained by PEOPLE, lays out for the first time some key details about the case.

Prosecutors have charged Chris, 33, with first-degree murder, among other crimes, in the the three killings. He was taken into custody on Wednesday night, two days after Shanann, who was 15 weeks pregnant, was reported missing by a friend. Her body and the bodies of her girls were found on Thursday.

In the intervening days, as investigators worked on what appeared to be a missing persons case, Chris initially said that he had talked to Shanann on Monday after waking up about 5 a.m., after she got home from a work trip just before 2 a.m., and he told her he wanted to separate, the arrest affidavit alleges.

Shanann Watts (right) and her daughters
| Credit: Shanann Watts /Facebook

Chris said that while he and Shanann “were emotional,” the conversation was “civil,” according to the affidavit.

Speaking with authorities later, Chris again said that he saw Shanann on Monday — this time around 4 a.m. — and “informed her he wanted to go through with a separation and they were both upset and crying,” police said in the arrest affidavit.

Chris claimed Shanann “told him she was going to a friend’s house that day.”

Finally, in another police interview, and after law enforcement allegedly uncovered that he was having an affair with a coworker, Chris said he would “tell the truth.”

He contended that he and Shanann had in fact talked about him wanting to separate after she got back from her trip early Monday but then he “walked downstairs for a moment” and when he got back to their bedroom he saw, via a baby monitor, that daughter Bella was “sprawled” and “blue” on her bed — apparently already dead — while Shanann was allegedly “actively strangling Celeste,” the affidavit states.

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At that point, Chris claimed, he “went into a rage and ultimately strangled Shanann to death” before loading “all three bodies onto the back seat of his work truck,” according to the affidavit.

He then allegedly took them to an oil site owned by the company he was working for (he has since been fired) and then buried Shanann and hid his daughters’ bodies in oil tanks, where they stayed for roughly four days.

Causes of death in the three killings have not been confirmed and neither has what authorities suspect to be the motive — though, in charging Chris with murder, they dismissed his account of what happened.

Those who knew the couple have described a seemingly normal home life possibly beset by marital tension. One friend told ABC News this week that Chris had grown distant: “He wasn’t being the loving Chris that he normally was. He wasn’t touching or hugging or doing stuff like that.”

Shanann, though, adored her family.

“That’s all she talked about,” Kris Landon tells PEOPLE. “She talked about her girls as miracles, because she had some health problems and didn’t know if she’d have kids. But she really embraced motherhood, and I thought she embraced her marriage, too. They seemed like partners. Amazing partners.”

At a Monday news conference where Chris’ formal charges were announced, Shanann’s father spoke briefly, sharing his family’s gratitude for the community’s support.

“Keep the prayers coming,” he said.

Chris is next set to return to court on Tuesday. He has not entered a plea and his attorney did not respond to PEOPLE’s request for comment.

• With reporting by STEVE HELLING

By Adam Carlson and KC Baker