You have to look at it like a crime novel, or a made for TV movie. The reason you have to look at it that way is this - all we can do is speculate from the evidence available to the public. Sort of like figuring it out from clues in a novel or in a movie.
A crime novel where police are called in to investigate a rape/murder, and where on page 2, they find the father's semen in the girl's vagina and his fingerprints on the blody knife would be a very short book, and not much of a thriller.
We aren't going to get iron-clad evidence in this case. Not enough for a conviction anyway. Can fibers innocently get entwined in the garrotte? I don't know. We have to call in fiber experts. Since both sides will do this, there's no doubt the fiber experts will disagree.
If this is ever solved it will be like on TV. The suspect will break down and sob and admit guilt. IOW, this case will never be solved, and will never go to trial.
But we can look at the evidence and ask where it leads us. Many of us think the RDI makes the most sense. We'll never have the sort of proof that will hold up in court, but we're still convinced.
I'll give you a few reasons for a start, then let others continue.
My theory of the case. JRDI
A. The ransom note is staging, there was never an actual kidnapping planned, which later went bad. Why ?
1. Dead bodies left in the house with RNs dont often result in payment of ransom.
2. It was hand written. Most RN authors would like to avoid it being
traced to them. The R's if covering up, wouldn't have had a choice.
3. 118K points to someone who knows JRs bonus. No real kidnapper or intruder would point to himself that way.
4. Its the longest, most rambling RN in history. It just doesnt seem
like a real RN.
5. Its written on the Rs paper, with one of their sharpie markers. A real kidnapper would have come prepared with the RN already written.
If its staging, who has more reason to write it, an intruder paedo with no intention of collecting ransom, or the Rs to coverup? I think the later.