This punk should have been charged with attempted murder. That is a charge that can be made when you continue to beat an unconscious victim, particularly a 12 year-old one.
The 16 year-old is being charged as an adult and is facing 20 years. I hope he gets them all. The jerk is wearing illegal brass knuckles.
I would also look into charging the girls. The one holding the camera seems to know what’s coming, and the girl who exits the frame at the last moment looks like she’s getting out of the way so the other moron can capture the punch.