I know we've been everywhere with Partridge theories... but hear my out!
We all know Red John thinks of himself as a superior being right? He'd never lead the Blake Association and have the same tattoo as his subordinates, that wouldn't be RJ.
But look at this picture, the cut is circular, not a straight line.
http://imgur.com/LWSqkel
It might be a far fetch... but what if his tattoo wasn't 3 dots... but a smiley face?