After the end of season 5, I had an intuition that there was some sort of conspiracy going on, and that Red John is only a parsona created by this conspiracy to hide their actions. Then the series reveal the Tyger conspiracy, which includes at least three of the suspects.
As individuals, none of the suspects give me the sense that they could be Red John. They lack the Red John drive to make killing a form of art, improving on his art and the need for reckognition (which is his self-destructive drive). They are all nascissits, but not the kind of psychopath who would kill just for the kiiling, to express themselves "one-upping" the police. They lack something.
But the "Tyger club" has all of it. The smiley face would serve as a marking that that killing was done by someone in the club, and the others should cover it up. The other parts of the M.O. (painted fingernails, face drawn with the left or right hand -- or with a plane --, weapon of choice, etc) would identify each member of the group as the one who did the killing. And the killings of people who talked thrash about Red Jonh in TV would be some sort of "brand improvement" needed to keep the conspiracy out of the media.
This would explain the incredible mobility that Red John has, and why the killing in Mexico don't fit the M.O. (did you notice that in that killing the face is not the first thing you see, like in all others?): someone new to the club did it, and got it wrong.
My other intuition is that this conspiracy spans outside law enforcement, and even created outside law enforcement, to cover powerful people doing dirty jobs to increase their power.
If that's the story, then someone in the conspiracy did kill Jane's family. I think this kind of job is usually done by a thug, so my guess is Smith.
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Some random stuff from 6x02: Haffner is displeased with Lisbon, as show by him shaking his head while saying that he likes Lisbon (a classic display of a desagreement between someones words and their true intentions/feelings). Bertram is so certain that he will "be there when [Patrick] catches [Red John]" that he smiles and nods his head.
