This is the thing Patrick Jane cannot--can never--tell anyone: he used to know who Red John was, and now he doesn't. He used to hold the evidence, and he destroyed it. He could have, should have, killed that man, and he didn't.
It's a part of his life he thinks about as little as possible, but he's never completely left it behind. He remembers the nights he scrubbed and scrubbed and scrubbed at his skin, removing every trace of the men who paid to use him. Every trace. Evidence down the drain. And when it was over--when he was eighteen and setting up a new racket, a new life--he needed to shed the inconvenient flinches he'd gained after those two years. He'd survived it by paying very careful attention to every one of those men, by learning everything he could about them and remembering it all with absolute clarity.
So he made himself forget. He wiped it away, beyond his own reach. He's always been good at playing with people's minds, and he's best at playing with his own. He didn't destroy all of it--he learned some important lessons in those years--but he made himself forget the worst ones: their faces, their voices, where they came from, what they did to him and why. All he remembers of them are the names he tagged them with in his mind, faded labels on emptied files. Smiling John. Greasy John. Diamond John. Red John.
He used to know, and now he doesn't. Patrick should have killed that man for what he did, while he was still working up to murder by abusing slender blond street hustlers, but he didn't. And now Red John is killing women--killing women here, in northern California, here where Patrick's wife and his daughter live. He's here, where Patrick has a whole life he built by forgetting, by walking away from the worst of the predators and leaving them out there to go after someone a little less clever.
His wife is scared about him working with the police on this; she wants him to get out of the business altogether. They have plenty of money, and Patrick could move on to something with a lower profile. He could do something honest, something their daughter won't be ashamed of when she grows up. He tells her this case is something he has to do.
He just can't ever tell her why.