This role would have the abitly after night one to sell his services to anyone, allowing them to pick someone to kill. If the target is killed, they die like normal. He gets points each time he makes a kill or hurts someone.
If the person he sells his services to targets the contract killer himself, he dies instead of the contract killer, making it a small risk of you dieing if you order a kill. This allows you to figure out who the contract killer is if you order a hurt on sombody, and you are hurt instead. You can only use a contract killer once.
He wins if the town wins.