Lets assume it was a life or death situation.
(Murder)Scenario A: You have to kill someone to survive. They don't necessarily deserve it, but their existence is putting your life, and (possibly) the lives of others', at risk.
(Cannibalism)Scenario B: You're stuck at sea on a raft with a family member. This family member just died of hunger, and you're turn is soon to come. You know where this is going.
Which one do you believe you're more capable of?