According to this film, you should never notify the FBI or other authorities if you get a suspicious neighbor. Not even if he looks like a terrorist and has a chemistry lab and receives constant deliveries from other suspicious-looking people. And especially not if you just lost your job and your wife just left you. They will just think you are paranoid and put you in an asylum, even if it turns out in the end that you were right all along. This is one of the reasons why terrorists have succeeded so far. This is how they put the first bomb in WTC and carried through their second assault. This is how they made the bomb for the Lockerbie accident and got it on board. People did not care, or were afraid of the unpleasantness to themselves if they notified the authorities.