El diablo
It is sad, but I think you are right. I am very familiar with crime and criminals. They don't want to repent - with exceptions of course.They always give themselves a good excuse - even a moral one - to what they do. Major criminals,like murders, like the kind of life that, sooner or later, implies another crime. They have no real respect for human life.
Their problem is their terrible selfishness.
It is true that prison takes away their humanity. But, what humanity?
I think that, in a matter like this, it is imperative to know the reality, how those men or women are.
About rehabilititation. It was a very gentle idea, and all western countries tried to apply it. But the results are very poor. Perhaps because states are not willing to spend as much money as it will be needed in those institutions. But for worst criminals, and I talk based on my experience - not as a criminal

- rehabilitation is something impossible. They want to be what they are, not what a society they dispize wants them to be.