Bruno Heller did mention to look for clues towards the end of S6X02. The clue that seem to be visible.
- The Doves Or Pigeons, i noticed when lisbon opened that room there was also cages in that room, could the blood be that of the pigeons? could partridges death be faked, i dnt think his dead maybe brett partridge was just a fake identity.
- Tyger Tyger (theres something about this its been uttered before by victims when they where about to die)

Why would brett utter the words Tyger Tyger, he could have just identified his killer?
Red John has always killed his victims he has never left any victim half dead. you always see the smiley face drawn by Red John, before you see the victims body, also i dnt believe for one second that he was interupted thats why he could not complete killing his victim as it seemed to be a settup, anonymous call to tip of cbi? im sorry it just doesnt add up.

My money is still on "Brett Partridge".