But there are some criminals who cannot and will not ever value human life; they know right from wrong and they don't care. Society is better off with them dead; it's an Old Yeller situation, plain and simple.
I generally agree with what you're saying.
(Re: bit in bold) - While I'm sure that this is true in some cases, how does a fair judicial system determine this? I spent a bit of time when driving between customers thinking about this yesterday, and peoples' motivations for committing crime differ and so therefore the approach for reforming them logically should be different as well - treating someone who "just wants to watch the world burn" with the same method as someone who thought they might get away with skimming their employer's accounts isn't logical. Even if one made a comparison between two violent crimes it's not even remotely logical that the causes of the crimes are the same.
So an approach that minutely examines the crime and the circumstances of the criminal and determines that person's reasons for doing what they did IMO is mostly a head job, if you want to find out what drives a particular criminal to commit crime.
I then need to make an enormous assumption that the people doing the examining have the skills and experience dealing with this branch of psychology, and they come to generally correct conclusions.
Many crimes are going to come down to very basic things, IMHO:
1 - Greed; people who want more but not having to work for it in the way that law-abiding people do.
2 - Attraction; people who are attracted to the achievement of pulling off a criminal act and haven't found an honest equivalent. Is there always an equivalent?
3 - Ignorance; (whatever crime) is the only thing they think they're good at.
4 - Lack of fear of the consequences; and possibly a combination of points 1-3.
Then responses to counter their reasons to commit crime need to be devised. The fourth is probably the most problematic to directly counter as the obvious conclusion is "give them something else to fear then". Other responses might be the sorts of things that many civilised countries already do (like ensuring that someone gets training to start them in a suitable career), but perhaps with more information about what makes that person tick, a better job can be done. According to some stats I read on a government website yesterday, the US has a reoffending rate of approximately 75%, compare that to the UK (again, stats from another gov website), apparently approximately 25-33%. Something is obviously wrong somewhere, ideally that figure should be significantly less (in both cases IMO).
IMO some of the sorts of responses could lead a judicial system down some very dark paths (e.g. 'A Clockwork Orange' or Room 101 in '1984'), but if you want better answers then you have to start asking more questions.