The FBI was concerned about her, but they specifically mentioned they had no probably cause to arrest her, there's no crime they thought she had already committed. Not sure a FFL has to ensure a person from out of state is following their own state's laws for a purchase, or if that liability is only on the purchaser. Makes sense that it would be only on the purchaser, what company could keep track of 50 different sets of laws that change every year? Not sure if the plane tickets or gun purchase raised the interest of the FBI. I would hope if they knew about a potential school shooter, the system could deny any background check until they can investigate. Not sure if that is legal though(maybe they could just not issue an approval and tell the FFL requesting why?)