I have a problem with it being an inside job. I just can't write that script once Burke hits Jonbenet, and the parents find her. Let's look at that. They find Burke has hit her, her eyes are rolling and she is brain dead. So Mum or Dad goes out and ties a rope around her neck and finishes the job. And Mum goes off to write the ransom note. About 6/7 hours later they ring the police. They have not slept. For then next decade, not one of them, no matter the pressure bought to bear, confesses. Surely after all that time, one of them would have turned on the the other two. If the cover up was the mother's idea, the father would eventually break down, and vice versa. The boy would be much more traumatized if he did it and lived through all that. Unless he had a major personality disorder - which has never come out. Being awkward and shy is hardly the same as being a psychopath.
The mother finds her dying daughter and garrotes her to cover up an accident?!
If such a thing happened, the parents would be in hysterics, trying mouth to mouth (DNA), calling for help. The boy would be totally traumatized by the consequenses of what he did, and his parents reactions. The parents would convince themselves it was an accident as they explained what happened to the police. This approximations sort of rings true. The cover-up script makes no sense regarding basic human nature.