The father purchased the gun as a Christmas present for the kid. Under normal circumstances, that would be legal. However, he admitted, to the FBI, that his son was "Struggling" and assured them the kid would only have access to a weapon with his supervision. I don't know how much of an investigation the FBI did or what would have been involved in proving that the comments made on line about shooting up the school were made by him. On the surface, it looks as if the FBI closed the case far too soon. But, there is very limited information out there.
