I find it hard to believe that an 11 year-old boy growing up in a town like Boulder would strangle his younger sister. That would be extremely unusual, at least in terms of crime statistics for a low-crime town like Boulder, CO.
This was a " sexual homicide ". Jonbenet was sexually violated, penetrated, before she was brutally strangled to death. DNA was left in her underwear that did not match the father or the brother. The fracture to her skull was post mortem, probably a coup de gras. I also think it was done with a metal baseball bat that was found in an alleyway in back of the house. In any case the boy was too young and didnt kill her. And the mother did not use a garrot and strangle her daughter because she wet the bed. Look at the autopsy photos. This was a brutal sexually motivated killing.