The subpoenas represent the first sign of a significant escalation of activity in the FBI’s broader investigation begun last July into possible ties between Trump campaign associates and Russia.
The subpoenas issued in recent weeks by the US Attorney’s Office in Alexandria, Virginia, were received by associates who worked with Flynn on contracts after he was forced out as director of the Defense Intelligence Agency in 2014, according to the people familiar with the investigation.
Robert Kelner, an attorney for Flynn, declined to comment. The US Attorney’s Office in Alexandria, the Justice Department and the FBI also declined to comment.
Talk of a grand jury has increased in recent days, following testimony by Comey before the Senate Judiciary Committee last week.