One of the reasons to support the death penalty is that the death of the worst murderers accomplishes at least one thing: They will never murder again. On the other hand, keeping all murderers alive ensures that some of them will murder again. They will either murder a guard or a fellow prisoner while in prison. Or they will murder someone outside the prison — either by arranging the murder(s) from within prison or if and when they escape from prison.
Therefore, opponents of the death penalty must acknowledge the blood that is on their hands when a murderer who would have been executed murders again.
Dennis Prager, “Opponents of Death Penalty and the Escaped Murderers”, Jewish Journal (19-25 June 2015), 9.