Federal prosecutors in Washington are using a grand jury to investigate whether fired FBI Deputy Director Andrew McCabe purposely misled government officials over his role in an unauthorized disclosure to a newspaper in 2016, according to a report.

The grand jury, impaneled for months, has summoned more than one witness who may be required to testify if McCabe is charged and the matter goes to trial, the Washington Post reported Thursday.

A spokesman for the U.S. Attorney's Office for the District of Columbia declined to comment to the Post.

McCabe, a 21-year veteran of the FBI, was fired on March 16, two days before he planned to retire on his 50th birthday so he could collect a full pension.

Attorney General Jeff Sessions dismissed McCabe following the Justice Department's Office of the Inspector General reporting "allegations of misconduct" by him to the FBI’s Office of Professional Responsibility.

The IG's official report, eventually released in April, found that McCabe "lacked candor" on four separate occasions, including three times while under oath, in connection with the disclosure to the Wall Street Journal.

The internal inquiry began when the FBI sought to determine if information published by the newspaper in an October 2016 article about the the bureau’s handling of the Hillary Clinton emails probe was due to an “unauthorized leak,” and “if so, who was the source of the leak.”

Investigators said McCabe allowed FBI aides to convey various facts to the reporter who wrote the story in order to “rebut a narrative that had been developing […] that questioned McCabe’s impartiality in overseeing” the investigation into Clinton's emails and the Clinton Foundation.

McCabe has disputed the report, claiming he had full authorization to share certain details and that he never intentionally misled officials.