If the kid is 15, see if you can find out how he is getting back and forth to the gym. If it a parent there is your window to find out if the kid is telling the truth or not. gotta be prepared to possably get some push back from the parents, but if it opens the door to help this young man out its prob worth it.
which begs the question where is he getting the money to buy them? thats money that should be put away for college or a first car, not steroids.. its insane if you think about it. a car gets you to and from school and work.. its a necessity for any kid living in the suburbs, that should be what he is spending his money on.