Washington CNN  — 

Justice Department prosecutors are investigating a media leak tied to the FBI’s Hillary Clinton email probe, a person familiar with the matter said, an unusually belated move that is prompting questions about political motivations since the new inquiry could involve one of the President Donald Trump’s most vocal critics, James Comey.

The former FBI director in 2017 told Congress about a piece of classified evidence that played a role in his decision to unilaterally announce no charges against Clinton in a press conference that usurped the role of his superiors at the Justice Department. Before that testimony, news reports had described the classified information.

But in recent months, investigators in the Washington US Attorney’s office have been looking into possible legal violations in the disclosure of that information. Investigators have interviewed witnesses about the media disclosure, according to another person familiar with the matter.

It’s not clear who the target of the probe is. But Comey’s role in the matter raises the prospect that prosecutors could end up examining his conduct as part of the probe.

The New York Times first reported the new investigation.

Justice Department officials last year cleared Comey in another media leak investigation related to the Russia investigation, a decision that drew harsh criticism from the President and his allies who had urged Attorney General William Barr to prosecute the former FBI director.

An inspector general report last year criticized Comey’s conduct in the Clinton email probe.

Comey has said that one reason why he didn’t inform then-Attorney General Loretta Lynch about his plans to clear Clinton at a July 2016 press conference was that the FBI had obtained classified information that could have raised questions about her impartiality.

CNN has previously reported on an email, that appeared to be Russian disinformation, purporting to show to show Lynch was exerting inappropriate interference in the Clinton email investigation. Despite Comey’s claims that the email played a major role in his decision to bypass Lynch and other top officials in clearing Clinton, the Justice Department’s inspector general found that by that point Comey “was already very far along in his plans to make a unilateral statement. Moreover, witnesses told us that the FBI determined based on various factors that the allegations that Lynch had interfered with the investigation were not credible, describing the information as ‘objectively false.’”

Comey’s handling of the Clinton case when he bypassed his superiors at the Justice Department was among the reasons Justice officials cited in a memorandum for the cause of his firing in 2017.