Appearing in court in Greeley, Colorado, on Tuesday, he pleaded guilty to all nine charges as the judge read them out.
Initially, Watts told police that he killed his wife in a rage; that she had strangled the daughters after he had acknowledged an affair and his intention to separate. If it goes as planned, Rourke said he will not fight the release of the autopsy reports for Shanann Watts and her daughters.
Taking a stab at Colorado governor John Hickenlooper, who had repeatedly opposed the execution of another death row inmate Nathan Dunlap, Rourke said: 'We explained to them the extraordinary delays that now exist in the state of Colorado as a result of in part the actions of our current governor.
Watts' voice quavered slightly as he entered the guilty pleas before Judge Marcelo Kopcow.
"They were very strongly in favor of a resolution in this case short of the death penalty", Rourke said.
Police found Shanann's body in a shallow grave Watts dug on the property of Anardarko Petroleum, where he had worked. "I don't want to be in the position to make that choice to take his, '" Rourke said.
"Shanann Watts" mother, Sandra Rzucek, told Rourke " '(Watts) made the choice to take their lives, ' " the district attorney said, the Denver Post reported.More news: Fast facts about the United States elections, seen as referendum on Trump
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He also pleaded guilty to unlawful termination of a pregnancy, as Shanann Watts was 15 weeks pregnant with a son her family said would have been named Nico, and three counts of tampering with a deceased human body.
Watts is represented by the Office of the Colorado State Public Defender, which does not comment on pending cases.
"That about as firmly as she could have said it to me", Rourke said.
During the plea hearing on Tuesday, he said the falsehood that Shannan killed the children was corrected.
"I know that that will never be fully realized because, obviously, the tragedy that sits before us today is the loss of four handsome lives".
Rourke said he hoped the agreement would bring some measure of closure for the family, who were present during the court hearing and the press conference.
Investigators never believed Watts' stories, Rourke said.
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.