Well, indeed one of the benefits of death penalty is that there will be less crimes especially murders and massacres, but there are always many things and ideas to get away with it. There are a lot of means of escape after committing a crime. Of course, with our technology, even drops of liquid and a pinch of salt will do in order for a person to do a crime and get away with it. We cannot give a "final judgment" to a person who committed a crime. Each person has their own mind and perspective of what life is, and what those people need is a point or position in which they can stand there and see another perspective or the right/correct meaning/purpose of life. If we are going to have death penalty,which is announced 1 to 10 days before it will be done, how can they realize and see that new perspective? That is why they are kept in a place where all they should problem is how to make themselves fixed and not how to get out of there; and also, it is the reason why they are fed, given some good indoor jobs, given a lot of freebies. They were there to solve their own problems so that they can be pardoned by their conscience (or maybe by the judges or government) and be free, maybe not with the place they physically live in but from where their spirit is jailed.