WATCH: Comey friend Jim Baker explains to MSNBC's Rachel Maddow how the Watergate 'road map' applies to Trump

MSNBC's Rachel Maddow on Tuesday interviewed Jim Baker, a former FBI official close to fired director James Comey who was the recipient of at least one of the director's memos.

After leaving the bureau in May, Baker became a fellow at the Brookings Institution and this week wrote a historical Lawfare blog post that outlines one the "road map" to President Richard Nixon's impeachment over the Watergate scandal — his establishment of a backchannel to a senior Justice Department official.

The former FBI counsel told Maddow that he wasn't aware of the "road map" — a somewhat sparse document detailing interactions between Nixon and Henry Petersen, then-assistant attorney general to the DOJ's Criminal Division — until it was released by the district court in Washington, D.C.

Peterson was, at the time of the conversations outlined in the road map, "in charge of effectively running the Watergate investigation" — a situation similar to that of newly-appointed Acting Attorney General Matthew Whitaker.

Maddow noted in one point during the interview that Baker's piece explained that "one of the Articles of Impeachment is based in part on [President Nixon] having improper contact with the Justice Department about this ongoing investigation."

She later asked him to speak in a general and hypothetical to a theoretical situation.

"If there were somebody at a high level in the Justice Department who was having secret communications with the White House about an investigation that involved the White House, that would be against justice Department rules," Maddow said. "That's the sort of thing that you would expect the inspector general to look into if there were credible allegations of that."

"Just speaking hypothetically and generically?" Baker asked. "Potentially, yes. The IG has a broad scope of authority and could look at that."

Watch below: