I can answer that one. There is nothing wrong with the death penalty for people who have been justly convicted. The issue is that many people have been unjustly convicted and sentenced to die BECAUSE OF PROSECUTORS' POLITICAL AMBITIONS, AND GUILT OR INNOCENCE BE DAMNED (yes, I'm shouting - this one ought to infuriate all of us).
In the abstract, the death penalty is a good idea, just like helping the poor is a good idea. It's that, just like helping the poor, it's become a government program gone wrong. Time to terminate it, or provide for a better review system so that us peasants don't get ground under the heel of an ambitious prosecutor.