Hello.

First I would like to say, that is more like "what if", than Sherlock Holmes type of theory.

But think about it for a moment, please. WHAT IF Red John is Rigsby?

I know it is almost impossible (he is too young, blah, blah, blah), but would not that be fuc*ing perfect in every inch? NOBODY SUSPECTS HIM.

Married, have a child... Ow! Is he not a cute one? And then BANG! SURPRISE MOTHERFUCKER! (~James Doakes) 

All those days that Jane used to mock him, that he used to think he is just normal, brave, but not very clever guy. That he is just Wayne. All those days Red John was smarter than Jane and felt satisfaction mixed with excitement because of Patrick lack of knowledge.

McAllister, Smith or Bertram being Red John is to obvious and it would disappoint me hardly.