It's not because of how bad things are in prison. I don't support the death penalty because of how final it is. Once you kill someone, that's it. There is no turning back. With the large number of innocent people being taken off of death row exonerated by DNA or other evidence, fuck that shit. I will never support the death penalty.
I cannot understand how a republican can fight so hard for life of a baby but not for an adult. I don't care what they are accused of doing by our gov't. I don't trust our gov't. So I am 100% pro life, because life is precious. They might take a life yes, so take their freedom, not their life. Otherwise you're no different than they are. "You killed someone, so you're a terrible person" but "You killed someone, so we're going to kill you and that makes us a good person" simply doesn't fly in the face of logic.
Self defense is perfectly fine, as you have a right to protect yourself or others. But to summarily execute someone in cold blood strapped down to a table or sitting in a chair or standing against a wall and try to call it "justice", um no.