As a teenager, I supported the death penalty. It seemed the best way to get rid of unwanted criminals to me at the time.
Since then, I've switched from being uncommitted to any religious view to being an atheist, which has altered my views on the morality of ending a life. Perhaps even more important on this issue, I've learned that (unlike the promises of many politicians) the death penalty is an ineffective deterrent, a more expensive sentence than life in prison, and an unequally applied sentence in terms of race and class.
Yeah, I'm certainly against it now.