Armywife- you're bathroom douching/rage theory does make a lot of sense. I don't agree about the head wound resulting from hitting a tub/sink, but was the result of hitting her with the flashlight. Either way, the bathroom scenario is plausible. The only thing that gives me pause is that BR was supposedly close by in his room when this occured. Unless he was still in the living room playing with his toys...or unless he had heard the bathroom-screaming event many times before.
I've never thought the murder itself was a sex crime. The vaginal stab was done to hide previous abuse, but I also feel that using an adult-size douche apparatus on a 6-year old girl would certainly cause the bruising, erosion and injuries as well.
If people that actually knew PR say she douched her daughter- then I believe she did. It sounds like it fits her controlling relationship with JBR. I can totally see it being done to "persuede" JBR to stop soiling her pants.
Though I would hope any vaginal swabs taken at autopsy would indicate it, and as far as I have read, there's no evidence of any chemicals, including vinegar, though she could have used plain water.