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FREDERICK, Colo. — Chris Watts has provided additional details about the murders of his wife, Shanann, and daughters Bella and Celeste, the Colorado Bureau of Investigation said Thursday.

Watts was interviewed on Feb. 18 by investigators with the CBI, the FBI and the Frederick Police Department at the Wisconsin prison where he is being held.

No specific details about the interview were released, but the CBI has documentation, including a written report and audio file, from the interview.

RELATED: Complete coverage of murders of Shanann Watts, daughters

The information will be made public on March 7 as part of the Colorado Open Records Act.

Watts previously did not disclose how or why he carried out the killings of 34-year-old Shanann, 4-year-old Bella and 3-year-old Celeste in their Frederick home on Aug. 13.

Watts initially made a public plea for help finding his family after they were reported missing.

But on Aug. 16, investigators found Shanann Watts’ body in a shallow grave at a Weld County oil well. The bodies of the girls were found in nearby oil tanks.

Weld County prosecutors said Shanann Watts was strangled and the girls were smothered.

Watts pleaded guilty in November to five counts of first-degree murder, three counts of tampering with a deceased human body and one count of unlawful termination of a pregnancy.

He was sentenced in November to three consecutive life terms plus 84 years in prison. He was moved to a Wisconsin prison in December.