Thank you for this excellent post annoyedgrunt84. This is very important:
"We seem to think that someone who has committed a crime, particularly a violent one has forfeited their humanity."

With regard to how we view others and treat them, I always come back to Sadhguru's words:
"There are no good people or bad people. There are only joyful people and miserable people. Each of us is perpetually oscillating between darkness and light."

And you are absolutely right, when you start looking into the childhoods of violent offenders, you don't find happiness and stability and safety. There are reasons why people go down certain paths. Sam Harris (neuroscientist) has even pointed out: If you had the brain of a serial killer, you'd be killing people too!