They would kill these little monsters before they have any chance of becoming adults with the same sort of attitude toward human life. I would submit that since they took the time to rip the little boy's clothes off, they clearly premeditated the crime on the aggregate.
Obviously the point about "if Canadians really believed in science and natural selection" will be lost on a number of people. That jab is appropriate because basic materialistic evolutionary thought would suggest that these children are natural predators who attack their own, and that we cannot rely on supernatural means to cure this fundamental personality flaw. The only solution is to fall back on artificial selection, and purge the personality flaw as it is extremely serious and dangerous to every child these three come into contact with. Putting them down is the logical solution for a society that believes that origin of human beings is through a process of refining undesirable attributes out of the population by either allowing the weak to die off or eliminating those who display behaviors that are destructive to the preservation and advancement of the species. I can think of nothing more undesirable as a personality trait than three marauding boys who attack and murder other children.
Clearly the only scientifically-sound solution is to terminate their lives immediately, as there is no empirical evidence that such people can be rehabilitated with any degree of consistency worth basing a criminal justice system on.
That is just the saddest thing I've heard in a long while. Your ensuing argument makes sense but of course it'll fall on deaf ears.
You are forgetting that humans evolved from nothing for nothing. A species really has no collective interest in whether it goes extinct or not. That is to say, the direction a species takes is not directed, so why not let the homicidal maniac variation step up to the plate and see if it makes Canadians more fit.
You do have something of a point there, Giraffe! However, if they are going around killing off healthy children with great abandon, they're only going to end up creating more trouble than they're worth for the greater population. However, if you would like to experiment with strategically unleashing them into crime-ridden areas, I'd be down with that >:)