Chris Watts was steadfast in denials that he killed his two young daughters — until investigators told him he failed the polygraph test he insisted they give him.

The 33-year-old was sentenced to life in prison this week for murdering his pregnant wife and two young daughters. As the Daily Mail reported, Watts had initially claimed no involvement in the killing of his four-year-old daughter Bella and 3-year-old daughter Celeste. He reportedly claimed that his pregnant wife, Shan’ann, had killed the girls before he killed her in a moment of anger.

But documents released by the Frederick Police Department showed that his story broke down quickly after Watts asked for a voluntary polygraph exam. After investigators told Watts that he had failed the exam, Watts told the truth — he killed his family after his wife discovered his extra-marital affair.

“I cheated on her, I’m not proud of it… she accused me of it… I denied it… And I feel horrible for it … like, she was pregnant… I didn’t hurt her… I cheated on her… I hurt her emotionally,” Watts told an investigator.

The Daily Mail found that Watts admitted he strangled his wife, saying he “was not a good man” and had a lot of rage. He also admitted to dumping the bodies of his two young girls “in a freakin’ oil tank” at a job site where he worked. Watts dumped the bodies early in the morning, then remained at the site to work for the day, the report noted.

Chris Watts’ Parents Defend Son, Claim Shanann Watts Was Abusive https://t.co/WwlbBQzLmC pic.twitter.com/l8cqzfv53J — Oxygen (@oxygen) November 16, 2018

There are other signs that Chris Watts’s wife was worried in the days before her death — though more for their marriage than for her own life. As People magazine reported, Shan’ann had texted a friend saying that Chris had been acting strange.

“He has changed. I don’t know who he is,” she wrote.

“He hasn’t touched me all week, kissed me, talked to me except for when I’m trying to figure out what is wrong,” Shan’ann later texted (via KDVR). “We’ve never had a problem in our relationship like this. No joke. NEVER. THIS IS TOTAL LEFT FIELD.”

“I just want to cry,” she added.

Though the friend tried to ease her fears, Shan’ann wondered, “What if he really doesn’t love me anymore?!” but hoped that the birth of their third child might help to change his feelings. Exactly one week later, Chris Watts would kill her and their two daughters.