“he knew what he was doing was wrong”
Of course he did just like murder or stealing etc.
However the ability to grasp the amount of harm you are doing to another is not all the way there yet.
I don’t support the death penalty for children, nor is it biblical. Death penalty is for ADULTS, and we can debate what an adult is, but it certainly is not a 12 year old.
The molestations we know of went on for over two years, when he was 14 and 15.