I find it interesting on ACA tonight (A Current Affair for the non australian readers) that Martin King's report freeze framed BR, SR and VR as "the husband", "the daughter" and the "brother in law" and repeated past footage of SR wiping dry eyes, BR eyes going all over the place during the media conference and VR spiel about Karen being overseas.
I think ACA would have inside knowledge and just not allowed to report it. I have thought since the start that SR knows more than letting on and it would be just like a father to protect his daughter if this was the case. Somehow I don't think we'll ever know the full story about this.
In the case of Vic Ranchem back in the early 80's he was the prime suspect, they never found Jackie's (his wife's) body and he went to his grave with whatever he knew or did. A detective even visited him on his death bed and said "Come on Vic, tell us where she is and what happened" and he still didn't tell.