A Colorado man who publicly begged for the safe return of his missing pregnant wife and their two daughters on Tuesday pleaded guilty to killing them, in a deal the prosecutor said spares him the death penalty.

Christopher Watts, 33, pleaded guilty to all nine counts against him — including five counts of first-degree murder — in the deaths of his wife, Shanann Watts, and their daughters, Bella, 4, and Celeste, 3, whose bodies were found on the property of an oil and gas company where Christopher Watts worked in August, according to a press release from Colorado's 19th Judicial District.

The plea deal includes a sentencing agreement that Christopher Watts will be sentenced to spend the rest of his life in prison, Weld County District Attorney Michael Rourke said.

Rourke said at a press conference that the plea deal was made with the support of Shanann Watts’ family, and after he explained what he called the "extraordinary delays that currently exist" in Colorado in putting prisoners to death.

"They were very strongly in favor of a resolution in this case short of the death penalty," Rourke said. Rourke recounted a conversation with Shanann Watts' mother, Sandra Rzucek, that helped make the decision.

"Sandy said it very, very poignantly to me. She said, 'he made the choice to take those lives. I do not want to be in a position of making the choice to take his,'" Rourke said. "And so that's about as firmly as she could have said it to me, and that was very compelling to all of us as we were talking about how to proceed on this case."

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

He appeared calm but emotional, speaking in a shaky voice as he entered his plea in court. He did not look at member of Shanann Watts’ family.

Shanann Watts, 34, and their daughters, Bella and Celeste, were originally reported missing in August. Chris pleaded for their return in interviews held outside the family's home in Frederick, Colorado, telling reporters "I just want them home so bad."

The Colorado Bureau of Investigations later said Shanann Watts and the girls were murdered inside their home. Shanann Watts' body was later discovered on the property of an oil and natural gas company that Christopher Watts had worked for. The bodies of Bella and Celeste were later found nearby in an oil tank.

Shanann Watts was 15 weeks pregnant at the time of her death.

Christopher Watts initially claimed to police after he was arrested that he killed Shanann Watts after she killed their daughters, according to court documents.

Rourke called those claims a "flat out lie" and said he did not believe Christopher Watts would give authorities a full, accurate and truthful statement.

"What I can tell you most affirmatively today, by what happened in the courtroom, is the spotlight that he tried to shine on Shanann falsely, incorrectly and frankly a flat out lie has been corrected," Rourke said. "The spotlight shines directly where it belongs — on him."

Asked if a motive has been determined in the case, Rourke said that investigators believe they have a "partial motive" and Rourke said he would have more to say about that following the sentencing, which is scheduled for Nov. 19.