FBI spokesman Christopher Allen insisted that the FBI aviation program is not secret but asked the Associated Press not to publish the names of the phony firms it discovered, saying the expense of creating new cover companies to hid the government's involvement that would saddle taxpayers with more costs. This is a big investigation by the Associated Press capped by an unusually long article which you may find here.
Some of the aircraft can also be equipped with technology that can identify thousands of people below through the cellphones they carry, even if they're not making a call or in public. Officials said that practice, which mimics cell towers into coughing up basic subscriber information, is rare.
Details confirmed by the FBI track closely with published reports since at least 2003 that a government surveillance program might be behind suspicious-looking planes slowly circling neighborhoods. The AP traced at least 50 aircraft back to the FBI, and identified more than 100 flights since late April orbiting both major cities and rural areas.
...A federal budget document from 2010 mentioned at least 115 planes, including 90 Cessna aircraft, in the FBI's surveillance fleet.
...The surveillance flights comply with agency rules, an FBI spokesman said. Those rules... are heavily redacted in publicly available documents...
...Officials say cellphone surveillance is rare, although the AP found in recent weeks FBI flights orbiting large, enclosed buildings for extended periods where aerial photography would be less effective than electronic signals collection. Those included above Ronald Reagan Washington National Airport and the Mall of America in Bloomington, Minnesota.
...At least 13 front companies that AP identified being actively used by the FBI are registered to post office boxes in Bristow, Virginia, which is near a regional airport used for private and charter flights. Only one of them appears in state business records.