Unfortunately, there have always been cases of sociopaths / psychopaths under the age of 18. Someone above used the word "feral" to describe them; that is the word I use. In and out of the criminal justice system from a very early age. By the time they are mid-teens they are hard-core, ruthless criminals. Sooner or later, if they are allowed to run free, they WILL commit a crime that results in either a life sentence, or death penalty ( if over 18 in U.S. ). They are a walking, stalking, time-bomb. They are past the point of rehabilitation ( if such a thing even exists ). Sometimes they come from the best of families, but more often then not, they come from disfunctional, broken homes, often the result of fetal-alcohol ( or fetal-drug ) syndrome...often several generations of which, each generation worse then the previous. Add in the recent glorification of "thug life" in modern culture ( music, video-games, TV, movies, etc) and what you have are dregs on civilized society. As I mentioned above, it is nothing new...look at "Billy the Kid", etc.
Not to bore you, but in a small town I was a cop in, was a kid named "Charlie"; his parents also had two older daughters, who never got into trouble. From an early age, "Charlie" was a chronic problem, vandalizing property, doing arsons, assaulting very young kids, etc. etc. This started when he way maybe 8 or so. Yea, he was given lots of mental health treatment, went through the juvenile system, etc. etc. but nothing worked. Finally he was remanded to adult status for some offense, when he got out of the joint at 20 or so, within a couple of days he stabbed someone for basiclly nothing, and back to the joint he went. No doubt, if/when he is released, he will continue his ways. As a society, should not the good, law-abiding folks be protected from the "feral"? Only way is to simply "remove" those who have overwhelmingly, time-after-time, proven that they are not compatible with civilization. I use "remove" in quotes because in this day and age, unless the perp is killed by a cop or citizen while committing a violant act, the only way we can "remove" is to imprison.
Time to jump off the soapbox!
Mark