It's so Odd!!
Since I start to watch this show, since the Pilot, I always though that Partridge is RJ. his body language shows that he hide something weirdoo, I guess that his not dead... the person Brett Partridge is dead, but not him like RJ.
 It's just a theory but.. Jane always sad that in most of times, the mostly obvius suspect are the real killer.
I think that the Tyger, Tyger conspirancy is just what is going next on the show, after jane kills RJ, RJ want to told Jane and Lisbon about this conspirancy.

So the mostly obvius suspect, for me is Partridge, or Haffner, but a go with Partridge cuz I when we se the last scene of 6x01 I'm acctualy see the pigeons reference.