So, no, obviously he's not an adult. That said he's been armed, trained (Even if inadvertently) to be effective at killing adults.
So what do you do? do you slap him on the wrist because his pubescent mind isn't fully ready for the responsibilities of adulthood? Obviously his family is incapable of keeping him out of trouble, One might even consider them to be a bad influence. The kid isn't evil but he's been programmed that way. How do we even address that in a safe way? Obviously the parents and the close family need to be held accountable. But what does that leave this scatterbrain brain scrambled little kid who's already showing a propensity to take lives?
I don't think anyone is advocating for a "slap on the wrist." The U.S. criminal justice system is the most draconian in the West, and doesn't do "slaps on the wrist," unless you're in a particular economic or social classes.
IMO, ideally, he would be sentenced for as long as it takes to rehabilitate him. Could be 5 years, 10 years, 30 years, or never, IDK, I'm not a psychologist. But, the U.S. prison system isn't really designed for rehabilitation either.
It's a punitive system, not a rehabilitative system. Americans still believe that punishment is the only way to handle deviancy. Most believe the punishments are not hard enough, this is the "tough on crime" take conservatives have been running on for decades.
The point of interest is what happens when those extremists are accused of crimes. Suddenly, exceptions should be carved out for them.
Yeah, we need to be asking what the purpose of trying the child in question as an adult here is:
Rehabilitation - I think the juvenile system would probably be better suited for this purpose, so no.
Deterrence - I don't think the knowledge that they might be tried as an adult has much bearing on their decision to commit the crime. I'd be willing to wager that people who do this sort of thing don't much care what the consequences are. They've given up on themselves and their own lives.
Removal - This strikes me as the main motivator. If the system has no way to rehabilitate, and recidivism is likely, then what other option is there?
Retribution - As much as the US loves its retribution, usually it's less keen to enact it on children. I'm sure some people would be happy about this aspect though.
Retaliation - I'll let y'all judge off of the tone of the rest of the comments for this one.
I would argue that if you reduce liability on a child, you should increase liability on those who take that liability away, i.e., the parents. That’s the whole point. Children are less liable because the parents guide them. Thus that liability shouldn’t be removed, it should be displaced.