First a kitten, then someone’s dog, then a small child - all killers have a starting point in their careers. Society, to protect itself, must catch them when they are young to stop it from escalating.
Torturing and killing a creature small and defensless is just the first step.
I have cats. Couldn’t manage a farm without them or the guard dogs.
The signs of being a psychopath can appear that young. What they need to find out is that if, like the Columbine killers, we are looking at one psychopath and a normal kid along for the ride, two psychopaths, or if neither are psychopaths and something else is going on here.
You're right. These kids have taken a first step down a bad path...