A New York police officer who arrested a photographer on assignment for The New York Times on a Bronx street in 2012 was convicted on Thursday of falsifying a record to justify the arrest.

The officer, Michael Ackermann, 32, was found guilty of a single felony count of offering a false instrument for filing. He was found not guilty of a second felony charge, falsifying business records.

Officer Ackermann had claimed the photographer, Robert Stolarik, interfered with the arrest of a suspect by repeatedly discharging his camera’s flash in his face. A subsequent investigation found that Mr. Stolarik did not own a flash or have one on his camera at the time.

Officer Ackermann was silent as Justice Michael A. Gross in State Supreme Court in the Bronx read the verdict after a bench trial that included emotional testimony from the officer, who admitted making a mistake. The judge did not offer an explanation for his decision.