> Third, how FBI ever knew of him buying a ticket? US is not East Germany where all ticket sales are wired to STASI in real time.
The TSA has exactly this system in place.
> This is supported by the fact that he was detained "minutes before boarding." Probably, it was only the fact of him passing the border control that was visible to FBI, the moment they saw it, they came with a rushed arrest warrant.
Or they were waiting for incontrovertible evidence of attempted flight from the country.
As far as I know, nobody at FBI have permission to read an arbitrary PNR, they can only obtain an order to get data from CBP for a specific person through a court order.
They don’t need to do that, all they have to do is tell CBP they want a warning if “Person X” attempts travel. The Advanced Passenger Information System requires airlines send CBP passenger info for all departing and arriving flights.
The TSA has exactly this system in place.
> This is supported by the fact that he was detained "minutes before boarding." Probably, it was only the fact of him passing the border control that was visible to FBI, the moment they saw it, they came with a rushed arrest warrant.
Or they were waiting for incontrovertible evidence of attempted flight from the country.