The death penalty is a valid sentence for pre-meditated murder. For a few reasons:

1. To remove the threat of this person killing someone else.
2. To possibly deter other murders from occurring.

Some would argue that the death penalty is murder so we would in fact only repeating the crime. However, the death penalty isn't murder. It is society's self-defense. Is it wrong for a police officer to speed in order to catch a speeder? Some cases require the offense to be repeated in order for justice to be served. If this were the case the world would be chaos.  Furthermore, if someone walks up to a person and punches them, then gets punched in return...you do not have two cases of assault.

There is also the argument that reason #2 above is not valid because statistics show the death penalty does not affect murder rates. This is a moot point. If the death penalty were supposed to be a deterrent then it would be called the death deterrent. It is called the death penalty because it is just that, a penalty given to the convicted. If it acts as a deterrent then it is "killing two birds with one stone" but I do not believe the death penalty is instated for the sole reason of being a deterrent.

Then there is of course the arguments of why not just give them a life sentence? Well, why not the death penalty? A prisoner serving a life sentence is not contributing to society but simply rotting in a cell.  The use society has on its people is for them to become functional members of society. I don't see life in prison as an alternative because if the convict were to kill others while in prison or worse, escape. Also, the convicts in prison for a long time earn the respect of others.