Those parents lives are ruined for life. There will never be a time where they don't blame themselves for what has happened, I also see a divorce coming their way as well. If they are smart they will seek professional help to get thru the grief.
This was just a sad incident where the blame was equally shared right up to the point where the driver of the RzR decided to drive away, At that point it became a crime plain and simple.
@jareddustin had at the time of your unfortunate accident where you were zero at fault left the scene of the accident. You would of gone to jail and rightfully so.
Leaving the scene of a accident is a crime and that crime overtakes any other crime that might of been being committed at the time of the accident.