It's tempting, but misleading, to say that such-and-such horrible murderer deserves the death penalty, therefore he should receive the death penalty. Why is it misleading? Because, in terms of retribution for what they have done, offenders may deserve far worse penalties than human government could rightly impose. They may deserve to be tortured, raped, or whatnot, but that doesn't mean government should do such things to them; it shouldn't. Likewise, they may deserve to be killed, but that doesn't mean government should kill them if they can be safely allowed to live. And why is that? Because the purpose of government, when it works right, is to serve the public good in accordance with reason, not necessarily to give offenders the worst they deserve. What offenders deserve sets only a maximum limit for justly imposed punishment, not a minimum limit. If the death penalty will serve the public good in accordance with reason, it should be used; if not, not. And expressing malice or vengeance toward offenders for their horrible crimes, as such, is not the same as serving the public good in accordance with reason.