From my point of view, the death penalty has always been totally illogical (as well as unethical):

If murder is illegal because killing people is wrong, then it's also wrong to execute them, because killing people is wrong.

Besides that, supporters of the death penalty are saying that the individual has no right to kill someone (it's murder - I agree), but the state has a right to kill an individual (I disagree). I would never put the power of life or death of an individual in the hands of the state - that's the ultimate in totalitarian control by the state over an individual.