lilongwe police malawi arrest 200 suspect members vigilante mob kill people believe vampires spokesman say tuesday nine people kill since mid-september southern malawi widespread belief witchcraft violence prompt unite nations u.s. embassy declare part country no-go zone attack spread last week blantyre malawi second large city 22-year-old man stone burn death another stone death accuse bloodsucking although medical experts deny existence vampirism malawi amos daka head medical society malawi say group aware one adequate clinical evidence support many claim date president peter mutharika visit part country affect violence month unite nations pull staff two areas southern malawi malawi vigilante arrest rise 200 vampire scare