Bad things happen to everyone. No one is perfect, and we all fall short of grace. Environment, circumstances, upbringing, and many other factors affect us throughout our lives. But, I believe how we react to those things (good or bad) is more important than those actions.
I learned a long time ago there were two things you can do to most bad situations/actions. The first real job I ever had was at a steel mill. I leaned on a I-beam someone had just used a torch on, when I wasn't looking. When I put my hand down, it didn't burn at first, so I left my hand there for a few seconds. Then it started to burn, and it didn't stop! Even after I put salve on it and bandaged it up, it hurt for three or four days. I asked the guy who was using the torch why he didn't tell me it was hot and he replied, no one told him when he got burned, and wanted to teach me a lesson (he said I would remember it better). Well, when the same situation happened a few days later, and I was doing the cutting, I warned the poor slob to move his hand. You see, I was brought up with the Golden Rule.
That being said, that 'person' who killed that child had a choice, and chose to torture and kill. I chose the death penalty because he is a monster, and I just don't care how a monster is created, it must be destroyed.
A great number of violent offenders are repeat offenders, and most pedophiles are never rehabilitated.