Sadly we live in a world filled with really bad people, even if they wheren't born as "bad" people, the system create contexts that turns people "crazy", no one is bad because it want it.
sometimes is better for the world to get rid of people that is mentally ill (mentally ill as a serial killer or continous rapist).
No one, ever, having a healthy brain and a normal life will do anything that make them pass trrought death penalty.
I personally belive that death penalty is need but in a rightous system, not in our current corrupted system.