FREDERICK — By pleading guilty to multiple counts of first-degree murder last week, Chris Watts has admitted to killing his pregnant wife Shanann and their two young daughters Bella, 4, and Celeste, 3.

This plea spares the 33-year-old the possibility of the death penalty, but also means many questions will remain unanswered since the case won’t go to trial.

Weld County District Attorney Michael Rourke said his office answered some questions about what motivated the heinous crime after Chris Watts was formally sentenced to life in prison on Monday, but conceded that much of what happened the day of Aug. 13 will remain a mystery.

Here is all our coverage on the case:

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Final release of evidence in Chris Watts case still doesn't answer "why"

Chris Watts transferred to new facility in Wisconsin

Lengthy documents detail marital problems, affair in Chris Watts murder case

WATTS-CASE 'I had no part in any of that:' Newly-released videos show Chris Watts failing polygraph test

‘You’re an evil monster:’ Chris Watts sentenced for deaths of pregnant wife, two young daughters

Chris Watts' parents question plea deal in murder of wife, daughters

Chris Watts reaches plea deal in deaths of his pregnant wife, two daughters

Coroner files request to seal autopsies of Shanann Watts, daughters after denial on technicality

Prosecutors ask judge to block public release of autopsy reports in Chris Watts case

Affidavit: Chris Watts claimed wife killed daughters, then he killed her

Chris Watts case: What we know

Chris Watts appears in court, faces minimum of life in prison if convicted of murder

Court documents: Body of Shanann Watts found in shallow grave

Documents: Defense filing suggests Watts girls were strangled

Police believe they've found the bodies of Shanann Watts' 2 daughters

Man accused of killing wife, daughters spoke to 9NEWS the day before his arrest

Financial issues plagued Chris and Shanann Watts 3 years before alleged killings

Colorado mom and husband described as 'perfect couple' ahead of alleged murders

Community mourns slain Frederick mother, young girls

Childhood friend talks about Shanann and the girls

Why hasn't Chris Watts been charged with killing his unborn child?

Could Colorado prosecutors seek the death penalty against Chris Watts?

WATCH

RAW INTERVIEW: Husband of Shanann Watts speaks to 9NEWS

Entire press briefing from Frederick police

Close friends of Shanann Watts horrified they welcomed accused killer into their home

RAW: Father of Shanann Watts thanks the community for its support