Gather enough evidence to reasonable have them arrested. Perform a citizens arrest. Be armed. Should they fight back, citizens arrest laws allow a citizen to use nessesary - but non excessive - force to hold another private citizen so long as they have witnessed the citizen being held perform a crime or have reasonable evidence to believe a crime has been committeed. If they pull weapons, shoot them. Record it all to be able to prove in a court of law that they had intent to kill you and you were defending yourself.