Two teenagers have died at large house parties that got violent with little warning in the last week. The latest, in Conyers, Ga., where 18-year old Dequavious Mapp was shot in the chest and died early Sunday morning. One week earlier, 18-year old Bobby Tillman was beaten to death at a house party in Douglas County. Conyers Police Chief Gene Wilson has a new plan to break up parties that get out of control before someone gets hurt. “I spoke to the sheriff and my staff.