Well I don't know how I could go about "proving" it exactly, but doesn't it make sense. I mean when you murder someone you KNOW it's wrong. However you might BELIEVE you're doing the RIGHTthing(it's still wrong though and the person knows it). I mean do you know of someone who sees murder as not a bad thing to do?
Again you keep referring to people I know. I only know people in my own society who have been brought up in a similar way with similar laws and morals. If I had been brought up in an African tribe where murdering was common place then maybe I wouldn't view it as such a bad thing