From the start, the sample has been driven by Attorney General William Barr's suspicions – critics call them conspiracy theories – the Trump campaign may have acted improperly. His embrace of theories aligns with President Donald Trump's chief grievance that he was the victim of a "deep state" spy operation that has clouded his presidency.
A picture of Durham's work has begun to emerge from other US agencies.
Barr, who has long had a reputation as a micromanager, has taken on an unusually hands-on approach to the sample as well.
Some words have already been interviewed, with a few words about Durham over the summer, some sources say. But at least two people have not been to investigate, according to two sources familiar with the investigation.
Durham has refrained from forcing some testimony with subpoenas, signaling that at least the department is not ready to call for a criminal investigation. But the possibility remains that criminal charges could emerge from the probation.
Michael Horowitz, the Justice Department's Inspector general, acknowledged as much in mid-September congressional testimony.
"I've had communications with him, but it's really – they're a separate entity that's working on the direction of the attorney general," Horowitz said. "I'm obviously independent."
Justice Department officials are limited to what Durham is looking for. A department spokeswoman declined to comment on this story, as did Durham and the Inspector General's office.
Durham has a small team that includes Justice Department headquarters employees assisting him,
Barr previously said that the review would include an examination
His department also wrote Some of what Durham was investigating regarding Ukraine, when a White House summary of the July 25 Trump and Ukrainian President Volodymyr Zelensky was released last month.
"Durham is separately exploring the extent to which a number of countries, including Ukraine, played a role in the counterintelligence investigation directed at the Trump campaign during the 2016 election Mr. Durham, which is evaluating, said Justice Department spokeswoman Kerri Kupec at the time in a statement.
In many ways, the Justice Department has buoyed the President's hopes. Trump has asked the prime ministers of Australia and the United Kingdom for help in the sample, which he views as discrediting the Russia investigation, CNN reported this month.
Barr's Trips have been unusual not just for their secrecy, but also for the Justice Department.