If a teacher prevented life saving treatment in order to enforce a rule about cell phone use, she most definently did kill the kid and should be prosecuted.
If you'll read the article, "Multiple 911 calls went out from Martinsville High School."
EMS was called. EMS came. The student made it to the hospital, and died there.
The article doesn't say whether or not anyone tried Heimlich on the student.
Did you see where the article said multiple calls had gotten through to 911 dispatch?
The teacher may be a raging idiot, but certainly did not cause the death anymore than a traffic cop who shows up at the scene of an accident and slaps the cellphone out of the hand of a bystander.
The kid choked on a hamburger and caused his own death. It's a pity nobody had training in the heimlich, and noone gave appropriate first aid.