My theory is that someone messed up.

What we know:

Physical description from a blind woman, who may or may not have been prompted by Ray T. to give a bogus description to the CBI.

We have possible sightings of RJ, in several scenes, which may all be red herrings.

We have seven names of suspects provided by RJ, neither confirmed or denied by Patrick.

RJ is fond of poet and artist William Blake's work.

Red John is not psychic, what he knows about Patrick and the CBI is provided by  his contacts in

law enforcement.

He is probably not a high profile figure in Law enforcement because he would be too easily recognized if he put on a guards uniform and walked down the corridor. For him to be effective he needs to be able to blend into the background. He also has some connection to Patrick's personal life including his time traveling with the Carnival, it would not be easy for some one to insert themselves and become trusted by the Carnival community.

There have been several good options for suspects, but none of them are on the list.