the ammount of senseless theories here makes me want do devote my time to work on the human genome....

I am 99% shure it is Virgil Minelli...  it has to be someone older... it has to be a male...why was his charachter thrown out of the series if not to let other suspects appear as red john.. he shook patricks hand.. he has connections due to 20 years in police and 9 years as cbi boss...he likes to catch fish- as does Jason Lennon... i cant remember the number of the episode but virgils says to jane; you are not in kanzas anymore dorothy; and jane replies; if i am dorothy,who are you? he doesnt answer but its obvious-- the wizard of oz :D 

and that william blake poem--- here is something else from Blake, a picture

http://www.wikipaintings.org/en/william-blake/dante-and-virgil-at-the-gates-of-hell

im sure 101% we allready seen RJ in the series...

considering age,intelect,connections in police,fbi

its Minelli