To add to my earlier theory, just to clarify.

Who says Bob Kirkland was 'really' hunting Red John? In the same way Jane mindfucks red John, Red John mindfucks Jane.
If Bob was really hunting Red John - the murder of Jason Lennon would not have taken place - simple as that. All Bob says to Lennon is "your MIND is clear - (classic hypnotism) - and then "have you seen me before". Lennon's memory has been 'washed' and then he is killed.
Still not sure which 'Bob's' we saw were Michael, and which were Bob - but guaranteed something is going to evolve from this.

Bob (Red John) knew Patrick Jane has been getting closer and closer from the minute Jane met Lorelei Martins. He needed to provide himself with some 'cover' and a legitimate excuse to find out just how close Jane was getting. What better way than to 'be hunting for Red John himself, due to a brother that been led astray - yeah right - lead astray by Bob more likely' and what better way to 'disguise' this?

Bob's big mindfuck of Jane: 'giving him the brother story' (which probably has some truth in it somewhere, but involving the 2 twins together: stronger twin saving the weaker - reading each other's minds - fighting the evil father etc) and hoping Jane believed it.
Kirkland has been playing TT and Jane in the same way Jane plays Red John: and in the process spinning a wonderful web in which he can escape (death to Michael) and hopefully disappear.
The failed bomb put an end to that.....

Kevin Corrigan would be a perfect red John. And boy, he would pull of a final showdown with Jane something special.

(Really hoping it's him - simply for the Corrigan performance)