When you were a child, at approximately what age did you first understand that it’s wrong to murder* a person?

When JFK was murdered. I was 12.

Very early on, maybe 6 latest.  Growing up in a small Ranching/Ag Community right and wrong were always stressed and reinforced.  We were also taught about justified use of force.  County Sheriff always had a lecture every year at the beginning of the school.  Consequently we had a very low level of violence per se
 

Around 5 or 6.  

I don't know.  I probably learned it through Bible stories and memorizing the Ten Commandments at a very young age.