In a video obtained by PEOPLE and excerpted by 9News in Denver (shown below), Watts was questioned for hours by authorities on Aug. 15, two days after wife Shanann, 34, and daughters Bella, 4, and 3-year-old Celeste went missing.
He consented to a polygraph examination, but he failed it.
“You did not pass the polygraph test,” an officer tells Watts. “We need to talk about what actually happened. I feel like you’re probably ready to do that.”
Watts, 33, maintained that he was being honest. “I didn’t lie to you on that polygraph. I promise,” he told the officer, before requesting a meeting with his father.
After he talked with his father, Watts again spoke with authorities. In the second interview, he claimed that he told Shanann that he wanted to separate. Then, he told them, he went downstairs and saw her killing Celeste in the baby monitor. He claimed that he ran back upstairs and strangled Shanann in a “rage.”
Authorities didn’t believe his story, and the video shows them handcuffing him.
“Chris, come stand up for me,” an officer tells Watts. “I’m going to have you face the wall.” Watts complies and allows the officer to handcuff him.
The footage was released last week as part of a trove of evidence prosecutors would have presented at Watts’ trial had he not agreed to plead guilty in November, sparing himself a possible death sentence.
Watts murdered his family on Aug. 13 and was sentenced to life in prison without the possibility of parole on Nov. 19. Prosectors have said his motive for the killings was his desire for a fresh start with Nichol Kessinger, a female coworker with whom Watts was having an affair.
Shanann was 15 weeks pregnant with the couple’s third child, Niko, when she was murdered.
After killing them in the early morning hours, Watts drove the bodies of his wife and daughters to a remote oil work site, where he stuffed the girls into oil tanks and buried Shanann in a shallow grave.
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Before his arrest, Watts did interviews with local media and pleaded for the safe return of his family.
The recent evidence-dump by prosecutors also included surveillance footage showing Watts loading up his pickup truck after the killings.