First, I stand by my comments. When a person decides (again, pre-meditated) to take the life of an innocent person - where there is a very clear context of first degree pre-meditated murder with clear intent - I don't care if the person is taking the life of one innocent person or 100 innocent individuals. Either way, it's completely monstrous and that person forfeits all rights.
Second, again, I now legally oppose capital punishment, because of the possibility of errors by the judge/jury. So I suppose you could say my first point is a theoretical one - but I still stand by my comments.
Finally - I wouldn't necessarily assume that life in prison is harsher than the death penalty. There are many published works by mental health professionals who have worked with murderers doing long-term sentences in prison. Prison gives them a chance to mentally celebrate in their minds (and even boast to other inmates) on their "conquests, over and over again. Also remember that every year, long-term inmates doing time for murder have injured or even killed prison guards.