TheChevra
Before asking this Shaylah, first make sure you know what a Moser is. There are people who think going to police about child molesters are mosrim. This is discussed on another thread. So before you kill anybody make sure you know that he is actually a moser or else you become a murderer. For th record Im not recommending you kill anyone, but if you do know of a real moser that is causing problems for teh community you should discuss this with a competent and discrete Rav before doing anything you cant undo.