Hurt people, hurt people; those who have committed these crimes are still human beings, just very damaged ones.

This does not excuse the crime and they should still be treat differently, however it does explain the crime. No matter how damaged a person, there is always possibility to work with them to change. They should still remain separate from the public, but be given intense therapy for retribution. Even if it takes a lifetime and they are never able to change in this lifetime and re-enter the public, a lot would be learnt from this in order to simultaneously put prevention systems in place to stop the number of damaged individuals in the first place.