How will that kid ever be close with his mum again?? Those sickos should not get the death penalty but instead get live and every Friday evening be tortured and given as much pain as possible to the point before it kills them so they can live on to the next session the following week. If this was in the UK and in our current prison problems I bet they be let off with a slap on the wrist because our prisons are full.
In relation to the pain/pleasure argument. My understanding is that when you experience a sensation of pain endorphins are released and act as natural painkillers for around 20 minutes, that's why after a motorbike crash you usually cant tell you have broken anything or where it even hurts for about 20 minutes by which time if the ambulance hasn't arrive, you're screwed. So, you're probably well aware that endorphins are the same chemicals that give a sensation of pleasure or happiness - i'm presuming that is the link although im not certain That story was disgusting and made me quite angry. I agree that they should be sentenced.
Pain can have a delayed onset due to shock or temporary disruption of nerve function. Endorphins take a while to kick in.