The Associated Press recently published an investigative report on secret surveillance flights conducted by the FBI over U.S. cities. One of the FBI planes was spotted flying over the city of Buffalo, NY this Wednesday, July 15, 2015.
The aircraft was a Cessna 182T and circled over the city for approximately two hours. The majority of its activity centered around Buffalo's east side, an area known for poverty, drugs, and violence. The AP report suggests the planes may be outfitted with surveillance technology for bulk data collection and mass surveillance.
The AP report is available here.
The plane is owned by National Aircraft Leasing Corporation, one of the FBI's front companies. Its registration number is N510KS. The plane departed from Buffalo Niagara Int'l Airport but seemingly landed on a small road in Angola, NY.
Below are screenshots of flight info and history from FlightRadar24.com: