It is only fair to record that many an ancient rich man distributed much of his fortune because of the fear of being killed by those who coveted his treasures.  The most despotic tyrants were subject to some restrictions; they were at least restrained by the ever-present fear of assassination.  Cain slew Abel, one the the most famous assasinations.  Primitive man did not recognize accidental death, there was always a culprit even in case of natural death.  Primitive men could kill their wives if their full price was paid; many towns simply accepted compensation money when someone was killed.  The blood guilt ceases to be a crime when participated in by all, by society.  Commandments against assassination:
Indwelling Adjuster was additional reason against assassination in Eden times. 
On a planet close to ours, in its main continental nation, recently they have gone so far as to attempt the prevention of crime by sentencing those who are believed to be potential murderers and major criminals to life service in the detention colonies.