I'm leaning towards this being done by or with help from someone close to the Rhodens. I just can't imagine someone who (according to LE) was able to plan the murders, but not able to see the consequences this would have for everyone. The last months must've been hell for all the surviving Rhodens, their extended family and friends. A motive bigger than the concern for the people you care about? Someone who was estranged from the family would make more sense, wouldn't it?
Oh, I don't know. We have looked at so many angles, probably also the right one. Problem is we don't get any confirmation when one of us is right, so we keep on guessing. Reader might've guessed to, but he needs proof and he doesn't have any. His only chance is someone confessing to what they know. When is he going to start arresting people?
Edit: I actually see a familiar name: http://wp2.pikecosheriff.com/?page_id=893
Which one?