His family background has nothing to do with it. As a society, if we allow "gee, my childhood has been/was terrible" to be an excuse for committing a crime, then we have to let every prisoner out of every jail.
If someone ignored warnings, that's a different issue and can be dealt with under the law. But it does not negate the fact that this child needs to be punished for what he has done. He has taken two lives, for crying out loud.
If he's so insane that he didn't know what he was doing, then he needs to be committed to a facility for violent 'insane' offenders. Going to counseling while living at home is not acceptable. He's obviously a danger to others.
I’m certainly not saying he should be sent home and just required to attend counseling sessions. Home obviously wasn’t conducive to his mental health before, and it isn’t likely to be now, plus, as you noted, he’s a danger to others at this point. What I’m objecting to is dealing with this as a criminal case, and an adult criminal case to boot.
This is a child who has in all likelihood spent most of his childhoood to date in severely dysfunctional homes, and has one or more mental disorders as a result. At 11, he certainly can’t be held responsible for not removing himself from this situation and getting mental health treatment before he completely lost it. There ought to be some adults held responsible for that failure, but not the kid.
It’s very different when we’re talking about someone 18+ who commits a crime like this, after a vile childhood that did some mental damage. First of all, they DO have the option of getting out of the home and at least requesting mental health treatment (if they get turned down, and then go out and kill somebody, we need to take a long hard look at the mental health professionals who insisted he didn’t need treatment). And perhaps more importantly, when someone has reached adulthood with their head that messed up, correcting the problem at all is a long shot and at best is going to take a very long time. With an eleven year old, there’s a very good chance that spending the next seven years in some of sane setting (perhaps first a secure juvenile mental health facility, and later a well-supervised group home or foster home) will result in a mentally healthy young adult. Saddling him with an adult criminal record for something he did when he was eleven closes off many doors to a decent life, meaning that even if he arrives at 18 in excellent mental health and with a meaningful high school diploma, he’s just going to start getting doors slammed in his face and become very angry and frustrated again.
Obviously we don’t know the whole background to this, and of course it’s possible that he’s really a “bad seed” and has had a reasonably sane and stable home life, and it just didn’t do any good. But given the tidbits of info we’ve gotten so far — no mention of his mother, dad living with pregnant girlfriend, pregnant girlfriend’s brother in law apparently having not rung any alarm bells when the kid told him he wanted to kill the girlfriend, and a seven year old stepsister whose reaction to a shotgun blast in her home is to get on the school bus as usual and not say anything to the driver about a problem — just adding it all up, I expect the full picture of what’s been going on in this household is something really appalling.