(CNN) A murder suspect told police in Colorado he strangled his pregnant wife in a rage after he saw her on a baby monitor strangling the couple's 3-year-old daughter, Celeste, according to court documents.

Chris Watts said the couple's other daughter, Bella, 4, was already "sprawled out" on the bed and blue in the couple's bedroom, according to an arrest affidavit from Frederick police.

Watts confessed to burying his wife, Shanann Watts, 34, near two oil tanks and dumping his daughters' bodies in the tanks, according to the affidavit.

But prosecutors paint a different picture of the killing. Watts was charged Monday with three counts of first-degree murder in the deaths of his wife and young daughters. Two additional first-degree murder charges accuse him of causing the death of a child younger than 12.

The 33-year-old father also faces three counts of tampering with a body, and a count of first-degree unlawful termination of a pregnancy, said Weld County District Attorney Michael J. Rourke, who did not reveal a motive.

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