(Re: spoilers, if you're up to date in the endurance run (specifically, today's VJ Endurance Run, there should be no problem.)
Deadly Premonition is one of those sorts of games I love to think about, as a lot is implied and people are generally unreliable so you have to look at things objectively rather than trusting everything you're told.
It's not particularly important, but I've been quite interested about the identity of the old Raincoat Killer.
We first hear the tale from Harry, who claims he ran to the clocktower, saw the military, and then as the bell rang 13 times, he ran and went into the middle of town where people will killing eachother, he got enraged himself, the Raincoat Killer (who turned out to be his father) was killing a lot of people, and he got knocked out by him.(And it'd be incredibly coincidental if he just ended up where the Raincoat Killer is, while driving, for no reason).
This story has some holes in it, the biggest one being that if the Raincoat Killer was slaughtering everyone, why did he just knock out Harry? Harry says himself that he seemed to be recognised and got attacked anyway and that people couldn't keep control, himself included.
And after Harry's regaled his tale, he basically says everything he's said isn't entirely true. To be precise:
"Just as you suspected, everything I have told you is gibberish. I never hacked into the FBI server. And I certainly know nothing about the red seeds. I thank you for listening to an old man babble on."
Yet his talk about the red seeds is accurate. He specifically doesn't mention his Raincoat Killer recollection and its truthfulness here.
In episode 25 when playing as the Raincoat Killer, the killer runs towards the clocktower. He hears the 13 bells ring - and everybody is going crazy before the 13th bell has rung (which is when Harry himself claims to have lost control). The Raincoat Killer also sees the military men in the clocktower, much like Harry claimed to have.
Would it not make more sense that Harry was the old Raincoat Killer, then, running TOWARD the clocktower rather than AWAY from it?
It would also explain why he wears that gas mask. It was pointed out in the ER that wearing it inside would be pointless if the issue is the outside is impure (especially when it rains) - if you knew you'd lost your mind and slaughtered a lot of people in a town, would you be taking risks? It might also explain why he's giving some hints.
Not to mention, if Zach got trapped in the Red Room due to... whatever Kaysen did when he was a kid, could Kaysen doing something similar when the Raincoat Killer got to the clocktower lead Harry to be there? We don't see what happens when he gets there, and the man in the Red Room type world sounds exactly the same as Harry, rather than a different voice like it would be if it was his father.
So anyway! That's my theory. :D It might not stand up to scrutiny and/or sidequest information, I don't know, but for now I'm sticking to it.