Blood cries out for blood. If your friend, husband, wife, lover, father, mother or child has been killed, it’s up to you to kill the killer. The Furies will drive you mad until you do. But then, of course, the killer’s friends and relatives have to kill you. On and on it goes. Then, one day, Athena told everybody to stop. Vengeance isn’t a personal matter anymore. From now on, the Law will punish the guilty. If the guilty are found guilty in a court of law, of course.
Capital punishment doesn’t exist to deter crime.
Capital punishment exists to end the cycle of revenge killing.
It’s just that simple.