I think for the evidence threshold to be crossed, it's not just how much evidence there is. It's how much there is that has no other explanation, no innocent explanation - basically the reasonable doubt zone. To me, this case is short of that bar. It's like the SP case before the body was found. Guy having affairs, jerk, lies about his wherabouts, doesn't cooperate with police, missing and no doubt dead wife - just short of the threshold - sometimes a jerk who wishes his wife was dead gets lucky and someone else kills her - not too likely, but a doubt I'd have to call reasonable - very borderline, but reasonable. Add anything to that, let alone a lead weight like body found where husband lied about being - done.
Ransom note that maybe was written by mother (handwriting matching being much more an exclusionary than inclusionary level of science), with facts that were related to the family (but possible for many others to know), body found in the home, fiber (that has many possible methods of transfer, not the least of which is from JBR herself) in the rope, parents noncooperative with police (that maybe showed a bias), no clear breakin or evidence of intruder (but this has been true before when there has been an intruder), mystery pineapple - it's not enough. Something more is needed, and at this point, it's unlikely to turn up any new evidence.
Add history on any of the family members towards any pedophilia, pre-indications they knew she'd be dying (like recent life insurance, etc.), something else - and I'd believe, and see it going to trial. Right now, I can see any possibility being true - and since I tend to go along with the police and be very pro-prosecution, I think that really means they'd have no chance with a jury.
