The defining characteristic of the wealthy "jet set" is that they don't lower themselves to scheduled airlines like the rest of us but fly wherever they want to go in private jets. It seems that Jeffrey Epstein, being in the upper bracket of jet-setters, had personal pilots on staff. If he thought that bought him confidentiality for his comings and goings, he needs to think again.
Pilots keep logbooks. See 14 C.F.R. § 61.51(a). Law enforcement has pretty much carte blanche to look at them. Id. § 61.51(i)(1)(iii).
Nicole Hong and Rebecca Davis O'Brien report for the WSJ:
Federal prosecutors in Manhattan have subpoenaed Jeffrey Epstein's longtime personal pilots, according to people familiar with the matter, as investigators seek to question the financier's employees in the wake of his indictment on sex-trafficking charges.
In addition to keeping logs, I would imagine the prosecutors would be interested in the flight plans the pilots filed with the FAA. Although I don't believe domestic flight plans require a pilot to identify the passengers, I'm certain that that number of passengers must be listed. However, if any of the girls were flown from the US to Epstein's private island, which seems likely, international flight plans do require passengers to be identified.
The more that comes out about this case, the more infuriating the previous non-prosecution agreement becomes.