It is purely conjecture to think that a kid writhing in pain from a fatal gunshot wound to the chest, having a hard time breathing and losing blood would refuse to say who shot him as if he was being uncooperative rather than fighting for his life. It sounds as though he shared all that he was able to; it would be easy to assume he was in shock and likely on the brink of unconsciousness. I would surmise that the boy was not able to indicate much more than it was not a self-inflicted wound. If paramedics knew he was not going to make it while performing life preserving measures, it would appear to be a dire situation.

My issue with the investigation is that you have a dying kid who expressing in some way that somebody else shot him.. why did they settle for a phone call from one of the two adults who happened to be in the room with the kid at the time the shot was fired? Take them both down to the station and press them for statements before they can collaborate or wash their hands.