So one thing I have learned (it is in my signature) is that people by human instinct have a hard time swaying from a story they hear. The lie becomes the truth because that is what our brain heard and processed. If that makes sense.
At this point I DO believe that part of RB story about Bella having a hard time sleeping and MM going to comfort her is true, just not on the night she died. RB used that memory because it probably stuck with her.
I believe that RB killed Bella on a different occasion and has not pin pointed a date because she knows some way somehow they will catch her in the lie with cell phone tracking or witnesses that MM was not at the house on that date. She's not stupid.
There is no evidence on the mattress that she was allegedly killed on of any aftermath of death, no evidence in the frig, car or even her little body. Med examiner said RB story is unlikely.
I think RB killed her alone in the house or maybe at the playground or maybe in the yard or maybe maybe maybe...her story about the murder is not believable and we go back to it because that's what the brain does.
Maybe MM was involved. Maybe he helped dump her body. But at this point there is absolutely no evidence that a jury can morally and legally convict him of any charges IMO. Also my opinion is the evidence all points to him not knowing. Evil genius planning on his part? I don't think the drugs, as heavily as he used them, would allow for a sharp mind like that. Drugs cloud the mind.