This was after, mind you, the towers had been hit.
The French intelligence service had provided the FBI with information regarding Moussaoui's membership in Al Queda, yet the leadership would not allow field invesigators to hold him as a terrorist suspect (they actually arrested him for overstaying his VISA).
This stinks to high heaven. Either the FBI's incompetent or the leadership should be charged with treason. "They didn't understand the significance of his arrest?" My eye. They knew very well that Moussaoui was involved with a known terrorist group that had killed Americans. They were told so by the French intelligence service.