If they know for sure this is what happened just skip the trial. Fry the little (This word is unacceptable on Trapperman).
At ten dose he have brain development and capacity? Many studies concluded its much older when the neurological pathways are fully developed.
Sure it's a messed up kid but why is he so messed up? Mommy spoiling him and never giving guidance for right and wrong? If your never taught it wrong or actions have consequences how do you interpret your world. All day killing on call of duty is as good as a simulator but the kid never has been exposed to death and killing anything and its permanent.
We don't have enough details. The kid may have major mental disability. Maybe mom was stretched to thin and just failed.
It could just be a spoiled young brat or a very abused child? Without more info its all just guessing.