Ivan Milat, the notorious backpacker serial killer, is not the most feared person in the prison system. Nor is it Martin Bryant, the man responsible for claiming 35 lives in the Port Arthur massacre. No, the person in Australia controversially ruled 'too dangerous to be released', the one who needs chains, leather restraints and a full-time posse of guards is Rebecca Butterfield: a self-mutilating murderer, infamous for slicing guards and stabbing...