Alas, this is the conundrum of our justice system.   Sending people to prison only appears to make them a worse person in a great many cases.   People are not coming out of prison rehabilitated.  

The same thing was said of the infamous criminal Clyde Barrow.  He was a rather innocent minor petty thief when he went to prison.   But he came out so full of hatred of authority, that he became a cold blooded killer, just like Christian.

Time in prison must dehumanize some people, for them to then come out and do these horrific things.