Guys, please remember what Jane said in one of the episodes (i don't remember season and episode) that the simplest thing solves the cases (problems etc.).  So i think RJ is someone from the first season, because we would figure that out at the moment, but ant the end of series we doubt it for no reasons (or a lot of reasons for digging to far). That just my opinion. BTW sorry for my english, it's not my primary language and i don't use it much. :) cheers.