Death penalty is just a human way to exterminate evil people. It is serve to as warning for those who will do bad things. For it is OK because all people are aware on that law before committing a crime so it is their choice and not a fault of the law.
Yes... that is a way to use the fear to "change the people"...
Unfortunately, the fear of the death penalty does not stop criminals from committing crimes. Each of them hopes that it will not find. The death penalty can only be punished for the crime, but I'm still in that she was.