Washington (CNN) The Justice Department's investigation into the origins of the Russia election interference probe keeps getting unwanted assists from the White House, raising questions of how the department will be able to defend the legitimacy of any of its eventual findings.

From the start, the probe has been driven by Attorney General William Barr's suspicions -- critics call them conspiracy theories -- that some of the officials overseeing the counterintelligence investigation of the 2016 Trump campaign may have acted improperly. His embrace of these 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. And some steps taken already point to the investigation being anything but a typical law enforcement inquiry.

But Justice Department officials have bristled at recent events that threaten to taint the investigation being led by John Durham , a respected Connecticut federal prosecutor who established a temporary office in Washington to conduct the probe.

Department officials have said Barr didn't know that Trump had mentioned his name in a July call with Ukraine's President suggesting he work with the attorney general and Rudy Giuliani, the President's personal attorney, whose activities are near the center of the congressional impeachment inquiry. And a senior Justice official objected after acting chief of staff Mick Mulvaney linked a freeze of Ukraine aid to the Justice Department probe.

A picture of Durham's work has begun to emerge from other US agencies and from people who are expected to be part of his review.

Barr, who has long had a reputation as a micromanager, has taken an unusually hands-on managing approach to the probe as well. He has traveled with Durham to foreign countries to help gather information, according to a person familiar with the trips.

Some witnesses have already been interviewed, with a few speaking with Durham over the summer, several sources say. But at least two people had been unwilling to speak to investigators, according to two sources familiar with the investigation. Durham has yet to interview any CIA officials, according to sources, but has been spotted in the hallways there.

Durham has refrained from forcing some testimony with subpoenas, signaling that at least publicly the department isn't ready to call it a criminal investigation. But the possibility remains that criminal charges could emerge from the probe.

Other signs point to the review being atypical among law enforcement efforts. For instance, the department's inspector general's office, a unit that operates independently, has shared information with Durham from its own foreign intelligence surveillance review.

Michael Horowitz, the Justice Department's inspector general, acknowledged as much in mid-September congressional testimony.

"I have had communications with him, but it's really -- they're a separate entity that he's working on at the direction of the attorney general," Horowitz said. "I'm obviously independent."

Justice Department officials have provided only limited information on what specifically Durham is looking into. A department spokeswoman declined to comment for this story, as did Durham and the inspector general's office.

The investigation

Durham has a small team that includes Justice Department headquarters employees assisting him, according to two sources familiar with the investigation.

Barr previously signaled that the review would include an examination of former British intelligence officer Christopher Steele's work compiling research about Trump and Russia in a dossier that was commissioned by Fusion GPS, a research and investigative firm.

His department also addressed some of what Durham was investigating regarding Ukraine, when a White House summary of the July 25 call between Trump and Ukrainian President Volodymyr Zelensky was released last month.

US attorney John Durham

"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. While the Attorney General has yet to contact Ukraine in connection with this investigation, certain Ukrainians who are not members of the government have volunteered information to Mr. Durham, which he is evaluating," Justice Department spokeswoman Kerri Kupec said at the time in a statement.

In many ways, the outlines provided by the Justice Department have buoyed the President's hopes. Trump has asked the prime ministers of Australia and the United Kingdom for help in the probe, which he views as discrediting the Russia investigation, CNN reported this month.

Barr's role

Barr's trips have been unusual not just for their secrecy, but also for how the Justice Department has gone about them, with the attorney general's personal work as investigator.

In other investigations, including special counsel Robert Mueller's probe , prosecutors used a formal process to send requests to foreign governments under the guidelines of a treaty. It's unclear if this has been done in the Durham investigation, raising questions about how any information that Barr has found could be used in court.

Among the Barr-Durham trips to gain public attention is one last month to Italy to meet with Italian officials in part to gather information on Joseph Mifsud , a shadowy professor whose discussions with a Trump campaign associate became part of the Mueller investigation, according to a person briefed on the matter. Mifsud has become a subject of fascination in some conservative media, where stories have claimed he was working for US or Western intelligence and was tasked to spy on the Trump campaign.

But not all foreign forays are going as planned.

British officials have expressed reluctance to become part of US political infighting this year, and have pointed to information they provided to US law enforcement in 2016, according to a person briefed on the matter.

And more recently, the Australian ambassador in Washington reacted sharply when Sen. Lindsey Graham publicly urged Australia and other countries to assist Barr's probe and used a characterization commonly found in conservative media to describe the role of a former Australian diplomat at the start of the Russia investigation.

Graham, a South Carolina Republican, said the Australian diplomat had been directed to contact a Trump campaign aide. Australian Ambassador Joe Hockey responded publicly that while his country would cooperate with Barr, "We reject your characterisation of his role," referring to the Australian diplomat whose tip to the FBI jump-started the Russia investigation.

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A 'serious red line,' Barr says

The attorney general had broad skepticism about the Trump Russia investigation and how it had started long before he took office.

Early in his tenure after he appointed Durham, he described concerns.

"There were counterintelligence activities undertaken against the Trump campaign. And I'm not saying there was not a basis for it, that it was legitimate, but I want to see what that basis was and make sure it was legitimate," Barr said in an interview on CBS in May.

He wanted a review of the intelligence, he said in that interview, because "the use of foreign intelligence capabilities and counterintelligence capabilities against an American political campaign, to me, is unprecedented and it's a serious red line that's been crossed."

It's not clear whether Barr learned information from his own sources or whether those suspicions were driven by conservative media stories that have spun a broad tale alleging US security agencies illegally spied on Americans as part of the investigation.

Barr has touted how the review is "broad in scope and multifaceted," and Mulvaney pointed to the review on Thursday as justification for the administration's demands from Ukraine.

With no sign of the review's conclusion in sight, it could continue to be used by the White House during the presidential election next year.

But in recent days, the White House and Justice Department have made clear that the review covers the waterfront of the President's lingering griefs about the Russia investigation.

Mulvaney said Thursday at the White House that the administration had held up aid to Ukraine in exchange for help with investigating the 2016 election, an act the House is now considering as it looks at potential reasons to impeach the President.

Mulvaney then invoked Durham. "So you're saying the President of the United States, the chief law enforcement person, cannot ask somebody to cooperate with an ongoing public investigation into wrongdoing? That's -- that's just bizarre to me, that you would think that you can't do that," Mulvaney countered to a reporter when pressed about the quid pro quo.

The Justice Department quickly distanced itself from Mulvaney, with a senior official saying, "If the White House was withholding aid in regards to the cooperation of any investigation at the Department of Justice, that is news to us."

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Durham's review is far from being done -- meaning any potential conclusions from it could be made public close to the 2020 election. A separate report by the Justice Department inspector general on t he foreign surveillance of former Trump adviser Carter Page is much nearer to being released, as soon as next month. Barr has been briefed on it as recently as last week, according to one source, and the FBI is also reviewing it, according to several people with knowledge. Horowitz said last month that his office had turned over factual findings to the Justice Department "for their marking."

Trump has also regularly claimed the report's release was imminent. But that appears not to be true, in part because witnesses involved have not yet received an opportunity to review draft versions, as is standard procedure.