I am not, there is an assurance that if innocents are sent into incarceration some of them will be murdered while there. Just as much of an assurance that some innocents would die because of a death sentence.[Then you ignore the possibility of the innocent being killed by other means during incarceration?]
There is a difference between the possibility of being killed while incarcerated, with the CERTAINTY of being killed, via a Death Penalty. You are flirting with Equivocation.
You are, in fact, assigning a too early end to an innocent life, just as much as you would be with the death penalty. Just because you won't know it doesn't take away that it will happen, I can assure you that it will. There is no way to avoid it.