Writer:
Tom Szentgyorgyi has written or co-written 12 episodes.Most of the episodes are significant and focus on Red John. He wrote the first two episodes featuring Haffner. [He also wrote the origins episode with Kirkland, but I believe Kirkland will no longer be a suspect after the upcoming episode.]

Tyger Tyger:
The poem is about an unimaginablly evil beast that was created. RJ is the beast.
Visualize is the creator. Haffner is a member of Visualize and has been
ever since he was a
teenager when he was a maladjusted and distressed boy.
He insists the cult helped him.
Visualize, likely unknowingly, helped Haffner become a well-adjusted serial killer.
[Probably just a coincidence: The poem was written by a British author. There's one British suspect.

Lisbon:
Haffner and Lisbon have some sort of past, which could be nothing unusual, but could be RJ trying to get close to the closest person to Jane.

Psychiatrist's Profile:
Haffner and Kirkland are the best matches for the profile.
Reed is a stretch since he is not very fit.
Stiles, Bertrem, and McAllister are too old.