I think the Police have a very good idea of who was involved, but a person who probably had a big involvement died before her body was found, however finding the evidence they needed was another matter.
All the clues point to that person, and although I don't believe he was the killer, he helped cover up what I think was a fatal accident.
I've never seen the link to the Transit keys before, but that just puts the lid on it for me.
Unsure how much I can post, as it's so long ago, I can't remember how much was in the MSM, and how much was through word of mouth, ie not just rumour, but knowing people that were interviewed and what the line of questioning was.