I feel that we are a far cry from a situation where we can feel comfortable that we are protected from dangerous murderers by life sentences.
Sirhan Sirhan was just up for parole; Manson I believe has been.
I'm not even comforted by life without parole, as legislatures or the courts can choose to go soft at any time.
Then there's always the chance of commuted of death sentences through gubernatorial or presidential pardons. We came close to that in Ohio with Dick Celeste in about 1990 when he set free several female accomplices to, and likely participants in, brutal murders. I believe there was nothing stopping him from going one step further and freeing the murderers themselves if he had chosen to.
I agree that the death penalty should be pretty rare, but NOT never. Not Bundy? Not McVeigh? Not Moussaoui? Not Osama?