This is a classic "right vs. good" dilemma. By acting, one person dies instead of five. So the Utilitarian has no problem. However, by acting, that one person who is killed would not have died otherwise. That person is as innocent as the others, so by acting one is choosing to kill an innocent person. Their family is not going to be happy about your actions. In fact, any deaths will be morally due to the actions of the "mad philosopher." Yet choosing to kill the one person, in isolation from the mitigating circumstances, clearly would be a wrongful homicide.