my theory for about two years

Red John isn't man,real human. It's an idea(?), like Kayser Soze. Many people killed as Red John. I thougt there is a organisation with rich and powerfull people (cops, judges, etc ) and they just keep looking on business. they want to be more rich and powerfull. when they need to kill someone then we see RJ. 
it is a masterpiece for a criminal. they "made Red John", a serial killer and everybody are looking single man