BDI pros:
easy explanation for why the parents never pointed fingers at each other. and for why JR is still proclaiming his family's innocence all these years later, when he is probably too old to go to prison and PR is dead. BR admits he went back downstairs later, which probably puts him close to the place and time of the murder -- at the very least, why didn't he encounter the intruder? pineapple stuff suggests BR and JBR had some interaction around that time too. if you believe the analyses of the 911 recording, he was awake at a time his parents claimed he was sleeping. lastly, RDI seems pretty likely, and if you see problems with JDI and PDI, BR is the alternative.