I picked undecided, but not because I believe the death penalty is wrong. There are some people in this world who, without a doubt, would make the Earth a better place without them in it.
However, I honestly think that death is an easier way out. Let them live in a cage for eternity -- the idea is to punish, right? Any purported judgement in the hereafter will keep, and empirically speaking, the only punishment we can garuntee is the punishment we can see and measure.
Also, you can always revoke life-imprisonment if for some reason a mistake was made, whereas you can never undo a death. In any system where human error is involved, I'm extremely reluctant to employ such a drastic, irrevocable action. This is especially the case now that I've begun to grow familiar with the US justice system as a result of my work in forensics.