Van Pelts Father: O'Laughlin says something to her about her father when they meet and seems impressed/intrigued. Also her father is mentioned by Jane in the pilot episode. Don't know if they shook hands though.
Another clue could be the words scribbled on the floor... HE IS MAN =  Heisman Memorial Trophy Award (The Heisman...named after JOHN Heisman) this is a football/baseball reference? Plus being a coach, as we know Van Pelts father is, you would have to travel around a lot. Could Tigers/Tyger be a sports team?
It has already been mentioned that VP has potential to be seen as easily fooled, she believes in the supernatural, questions Jane, has a hidden/troubled past...a sister who died?

I think VP or someone in the immediate team (Minelli?) could either be the insider or unknowingly helping RJ.

I really hope it doesn't turn out to be PJ in some sort of rubbish 'personality twist' ending. I think this is unlikely.

My other plausible guesses would be Partridge or Kirkland.