I'm not refusing the debate on those terms or ignoring the crimes they've committed.
There's a reason the law (to much criticism) doesn't really consider what the father, in your example, thinks. Let's consider the idea of asking the heartbroken, confused, angry, bitter victims' families & friends how they think said convicted criminals, rapists, & mass murders should be dealt with. And you know where that leads us? Bitter retaliation. Revenge. Humiliation. Eye for an eye stuff. It turns logically into (Saudi Arabia): lets medically paralyse the bastard, because that's what happened to our son/daughter after his crimes. It turns into: he tortured; we should torture him. This is barbaric. Don't say this wouldn't happen; it would. I don't want to be part of a society which says this is acceptable or justified; I don't think that it is. And, again, I say: what does this say about us, if this is how we choose to deal with those in society who commit heinous crimes? It says to me, that everything that motivated them (murderers), seems to motivate us too: hate, revenge, etc. It says we are morally bankrupt hypocrites.
"You need to look at their evil and the pain they have caused straight in the face first. "
And what? Deal all that evil & pain right back at 'em!? Become everything they are?
"When, if ever, is the state justified in taking the life of an individual?"
It's not. That's what I think. There's no need for it. We're not animals.