I think Dr. Royston is Red John , I have mi reasons:

1- When Miranda Martins (Lorelei Sister) was killed she wrote on the floor "Roy". Red John uses ROY  of nickname and Dr. Daniel Royston too.

He fits with all the clues:

1- Hes attractive and he looks smart.
2-Fits age.


Look at this conversation of Lorelei with Patrick:

PJ: Red John killed your sister!
L: No he didnt!
PJ: Yes! She wrote "ROY" on the floor and we BOTH KNOW WHO USES THAT NICKNAME!

Perhaps he doesnt have friends in the CBI or in the FBI and perhaps he didnt worked in Visualize.