President Trump’s former attorney says there are “reports” that retired Lt. Gen. Michael Flynn referred to his own wiretap when he was interviewed by two FBI agents in January 2017.

If the information from attorney John Dowd is correct, it would add to the body of evidence that Mr. Flynn was not deceptive because he knew the FBI knew everything he had said.

He pleaded guilty last December to one charge of providing false information to the agents and is awaiting sentencing.

Since then, an air of mystery has surrounded his plea.

Fired FBI director James Comey has told two congressional committees that agents didn’t believe Mr. Flynn purposely misled them when he denied talking about two topics with former Russian Ambassador Sergey Kislyak––Obama-ordered sanctions and a pending United Nations vote. He had in fact discussed those two issues.

Mr. Comey, on a book tour for “A Higher Loyalty,” denies he ever made those statements, prompting Republicans to release his closed-door remarks from last year.

Mr. Dowd referred to “reports” in a letter to the editor on Monday in the Wall Street Journal.

He told The Washington Times that he heard the information while defending Mr. Trump in Special Counsel Robert Mueller’s probe into Russian election interference.

“Congress needs the FBI ‘302’ report of the Flynn interview,” Mr. Dowd wrote. “There are reports that Gen. Flynn referred to the FISA wiretap of Ambassador Sergey Kislyak conversation at the outset of the FBI interview. If those reports are true, his reference to the complete and accurate wiretap precludes any charge of false statement.”

FISA is the Foreign Intelligence Surveillance Act under which it is assumed that the FBI maintained a wiretap on Mr. Kislyak as the agent of a foreign country.

Mr. Dowd said the District Court judge should never have accepted the plea obtained by Mr. Mueller.

“The Flynn plea on Dec. 1, 2017, was improvident and should not have been accepted by the court,” he wrote. “A provident plea to 18 USC § 1001 (false statement to FBI) has two elements: A) that it be false; B) that it be material to the inquiry. The Mueller investigation concerned possible collusion with Russia during the 2016 election campaign that ended Nov. 8, 2016.

“The questions and answers in the Flynn FBI interview occurred in December 2016 and involved conversations with the Russian ambassador in December 2016—after the 2016 election campaign, and are thus immaterial to the stated inquiry of collusion during the 2016 campaign. Gen. Flynn kept his security clearance.”

The day after Mr. Flynn pleaded guilty, there was a leak to the news media that one of the agents who interviewed him, Peter Strzok, had been fired by Mr. Mueller for texting anti-Trump messages to his FBI lover.

On Friday, Senate Judiciary Committee Chairman Charles E. Grassley, Iowa Republican, sent a letter to Deputy Attorney General Rod Rosenstein and FBI Director Christopher Wray.

Mr. Grassley renewed his request for a transcript of the Flynn-Kislyak telephone call which Justice denied last year. He also is seeking a copy of the agents’ interview notes, or form 302.

“Contrary to his public statements during his current book tour denying any memory of those comments, then-Director Comey led us to believe during that briefing that the agents who interviewed Flynn did not believe he intentionally lied about his conversation with the Ambassador and that the Justice Department was unlikely to prosecute him for false statements made in that interview,” Mr. Grassley wrote.

At the time Mr. Comey appeared before Judiciary staff in March 2017, a law enforcement agent on loan to the committee took notes.

He quoted Mr. Comey as saying the interviewing agents “saw nothing that led them to believe [Flynn] was lying.”

District Court Judge Emmet G. Sullivan has ordered Mr. Mueller to turn over any exculpatory evidence on Mr. Flynn.

The order has led to speculation that the guilty plea is on shaky legal ground, but there has been no confirmation.