The Justice Department inspector general’s office said on Thursday it would open an investigation into the decision in October by James B. Comey, the F.B.I. director, to inform Congress about a new review in the Hillary Clinton email investigation — a move Mrs. Clinton has said cost her the election.
The inquiry is not a blow for Mr. Comey only. It also draws negative attention again to the F.B.I. on an issue that agents had hoped was behind them.
The inspector general’s office said the investigation had come in response to complaints from members of Congress and the public about actions by the F.B.I. and the Justice Department during the campaign that might be seen as politically motivated.