Its Patrick Jane. 
Just read the whole paragraph before disagreeing with me-


The whole series is taking place inside Patrick Jane’s head. He’s still in the correctional facility and this is his way of justifying the death of his family (which he committed in a fit of rage). His sub-conscience created the character of Red John, who he could blame. All the episodes are false or imagined memories associated with his pursuit of this fictional character. In the end we will find out that PJ is the one with the tattoo on his shoulder. A scene will come at the end of the season when all the suspects are dead and Patrick will look at himself in the mirror at this big revelation will dawn on him.


Sorry, for ruining your series guys. I couldn’t help it. ;-)