WASHINGTON — For years, President Trump has complained bitterly about F.B.I. officials who investigated his campaign’s ties to Russia, and about the “rogue bureaucrats of the Deep State” at the intelligence agencies, portraying them as enemies out to delegitimize his presidency.

Now, a special Justice Department inquiry investigating those officials has taken on another of Mr. Trump’s irritants: leaks to the news media.

Investigators for John H. Durham, the U.S. attorney in Connecticut leading the investigation, have asked witnesses about news articles published in early 2017 that former administration officials blame for prompting the chaos that dominated the early days of the Trump presidency, according to three people familiar with the inquiry. Among them was a Washington Post column about Michael T. Flynn, the president’s first national security adviser, one of the people said.

What Mr. Durham has found is hidden from public view, and the coronavirus pandemic has slowed his progress, the people said. But Attorney General William P. Barr has promoted the investigation in recent days, saying that Mr. Durham has uncovered “troubling” problems and indicating that some results could made public before the general election in November. Mr. Trump has said he looks forward to the outcome of the inquiry, and a report or criminal charges before the election would all but assure that he weaponize it for political gain.