More Words, Deeper Hole

The crime fiction of the 1950s, for instance, does produce a lot of "the criminal's POV" story, but if noir includes writers like Hammett and Chandler, I'd have to disagree with your generalization. Sometimes Marlowe knows who committed the murder (or other crime) because he witneses it; otherwise he has to figure it out, and sometimes he doesn't. Chandler famously remarked that even he didn't know who killed the chauffeur in The Big Sleep. Hammett (in The Thin Man) does make a big deal about the difference between knowing someone committed the crime and proving it, but that's at the end of the book, not the beginning.