What, M is not considered film noir? For me, film noir has as essential elements the shadows (even in noir shot in the California desert, they still manage to use shadows in the narrative), and creepy/voyeuristic camera work that gives away measured clues. So what do we first see of Peter Lorre? Why, his shadow... across his own warning poster!
Of course, Fritz Lang went on to become a successful noir director in Hollywood. I had the pleasure of watching a Fritz Lang retrospective series 15 years ago in Portland, OR. Still some of the best films I've seen... and they played as double featu