My opinion, he did it....................
My father in law was a policeman for many years, then an investigator for the DA’s Office, and worked his way up to Chief Investigator for the DA’s Office. So I would always ask him about cases and he was always right in the end. I asked him about this one and he said...someone in the family.
The grinning psycho did it
I always thought so too, but proving it...?
Boulder PD were accomplices after the fact.
I wonder if this case can be solve via DNA analysis, which I believe was not “a thing” then, or at least in its early stages and not dependable. There must’ve been some hair, skin cells, bodily fluids, etc., left behind and sitting in some evidence box. Even if it didn’t prove who did it, at least it could exclude known suspects such as family members.