The Cat Woman decided she had to exploit a division in the Metropolis population and what better to do it except by giving birth to the son who was half Chief Gordon and half The Joker who would one day...become Chief and achieve his goals of communal peace utilizing unusual Joker methods. If you can't hear you must feel. You have elected the way of pain. He never kills anyone but every person who falls under his unusual approach gets a signature card stamped with a Blackhawk insignia sort of like the Blackhawk team logos. That is how you know its him.