There's no evidence to support PR committing the head bash, but you support this hypothesis, yes?
There's way more holes in a PDI theory than in a BDI one (who molested JBR, why no divorce, why no history of abuse, why no coherent explanation for BR's nonchalant attitude, etc.), but we'll agree to disagree.
ETA: We don't know what kind of shirt BR was wearing, so to say his fibers were not found is erroneous.
Sorry, OliviaG1996, but I can't go along with you. From where I'm sitting, PDI is the only one that ties up the majority of facts.