I'm looking for manga\anime, forgot it's name-
only thing I remember is a scene where the father is thinking about his son and dead wife and asks himself "what are you... made of iron?!"
Also I remember the main protagonist is the son, being evil who poses himself as innocent, as they (him, his father and 2-3 more dudes) try to find a killer, while the killer being the son all along acting like saint.