There was a manga I had saw on here a few years ago that seemed to focus around a white haired male detective character, and a black haired seemingly monster male character with a penchant for dismemberment. Though there seemed to be quite a bit of dismemberment throughout the series. Would really put my mind at ease if anyone knew the name of this. Wish I had more info to give.
I recall a scene in it where a bunch of school girls end up getting cut up by lasers in a manner similar to resident evil 1 basement scene.