Rj doens't have to be someone, i mean,who said  red john is a person, it's just a name, this name can be used by several people, so that means the three suspects can be three red john's, red john can be several people at the same time, it's an organisation as they said, red john can be just an organisation not just a single person, that's why lots of people have this three dots tatoo, they are in that organisation but some might be the killers, other ones might just help..
That will explain why red john is so smart, i mean, is not one person, is lots of people having lots of information at the same time!

My english sucks but that might be!