Prosecuted for Murder

I think that it can be correct or moral to send someone to their deaths, you have to take in account how bad was the crime they commited, no one has the right to kill another human being and less call it a law, how cynical? If we put it on a logical point of view yes, maybe death penalty will decrease violence in a country but will it be allways fair? I always think on both sides of the coin, you can also argument that a killer will always be a killer even after sentencing him for 30 years of his life in prison, after he comes out he will do exactly the same thing and kill again. We always have to be in the side of logical thoughts and feelings, will it be better to make a killer suffer for all his life so he changes his mind or kill him and finish with the deal? If a murderer took someone else's life maybe it can be taken to court and be charged with death sentence, only to be fair with the other person who lost his life for no reason. You have to analyze every perspective before you take a decision and also be sure that the person dying for a crime is the right person. So in the end it could be moral to give the state the power to kill someone only if what they are doing is logical and and positive for more than one person.