What motive Does Garrett Mason(The Black Dahlia) have to murder all those women in LA Noire?

Don't think he had a particular motive, he was just messed up. I think the only sort of motive that's ever discussed in the game is his obsession with power and superiority, he enjoys feeling superior to the police department and enjoys mocking their inability to catch him. Other than that, he's just a bit of a psychopath.