WASHINGTON — Federal prosecutors reviewing the origins of the Russia investigation have asked witnesses pointed questions about any anti-Trump bias among former F.B.I. officials who are frequent targets of President Trump and about the earliest steps they took in the Russia inquiry, according to former officials and other people familiar with the review.
The prosecutors, led by John H. Durham, the United States attorney in Connecticut, have interviewed about two dozen former and current F.B.I. officials, the people said. Two former senior F.B.I. agents are assisting with the review, the people said.
The number of interviews shows that Mr. Durham’s review is further along than previously known. It has served as a political flash point since Attorney General William P. Barr revealed in the spring that he planned to scrutinize the beginnings of the Russia investigation, which Mr. Trump and his allies have attacked without evidence as a plot by law enforcement and intelligence officials to prevent him from winning the 2016 election.
Closely overseen by Mr. Barr, Mr. Durham and his investigators have sought help from governments in countries that figure into right-wing attacks and unfounded conspiracy theories about the Russia investigation, stirring criticism that they are trying to deliver Mr. Trump a political victory rather than conducting an independent review.
And on Thursday, Mick Mulvaney, the acting White House chief of staff, tied Mr. Durham’s investigation to the Ukraine scandal, infuriating people inside the Justice Department. But Mr. Mulvaney’s comments also put the spotlight on the fact that Ukraine is one country that Mr. Durham has sought help from. His team has interviewed private Ukrainian citizens, a Justice Department spokeswoman has said without explaining why.
A spokesman for Mr. Durham declined to comment. Mr. Barr has said that he viewed some investigative steps as “spying” on the Trump campaign and that there was a “failure among a group of leaders” in the intelligence community. He has said he began the Durham review in part to prevent future missteps.
Mr. Durham has yet to interview all the F.B.I. officials who played key roles in opening the Russian investigation in the summer of 2016, the people familiar with the review said. He has not spoken with Peter Strzok, a former top counterintelligence official who opened the inquiry; the former director James B. Comey or his deputy, Andrew G. McCabe; or James A. Baker, then the bureau’s general counsel.
Those omissions suggest Mr. Durham may be waiting until he has gathered all the facts before he asks to question the main decision makers in the Russia inquiry.
Though criticism has been set off by the revelations that Mr. Durham is examining politically tinged accusations and outright conspiracy theories about the origins of the Russia investigation, he would naturally have to run down all leads to conduct a thorough review.
The president granted Mr. Barr sweeping powers for the review, though he did not open it as a criminal investigation. That means he gave Mr. Durham the power only to read materials the government had already gathered and to request voluntary interviews from witnesses, not to subpoena witnesses or documents. It is not clear whether the status of the review has changed.
Mr. Durham’s investigators appeared focused at one point on Mr. Strzok, said one former official who was interviewed. Mr. Strzok opened the Russia inquiry in late July 2016 after receiving information from the Australian government that the Russians had offered damaging information on Hillary Clinton to a Trump campaign adviser. Mr. Durham’s team has asked about the events surrounding the Australian tip, some of the people familiar with the review said.
Mr. Durham’s team, including Nora R. Dannehy, a veteran prosecutor, has questioned witnesses about why Mr. Strzok both drafted and signed the paperwork opening the investigation, suggesting that was unusual for one person to take both steps. Mr. Strzok began the inquiry after consulting with F.B.I. leadership, former officials familiar with the episode said.
Mr. Durham has also questioned why Mr. Strzok opened the case on a weekend, again suggesting that the step might have been out of the ordinary. Former officials said that Mr. McCabe had directed Mr. Strzok to travel immediately to London to interview the two Australian diplomats who had learned about the Russians’ offer to help the Trump campaign and that he was trying to ensure he took the necessary administrative steps first.
It is not clear how many people Mr. Durham’s team has interviewed outside of the F.B.I. His investigators have questioned officials in the Office of the Director of National Intelligence but apparently have yet to interview C.I.A. personnel, people familiar with the review said. Mr. Durham would probably want to speak with Gina Haspel, the agency’s director, who ran its London station when the Australians passed along the explosive information about Russia’s offer of political dirt.
Many of the questions from Mr. Durham’s team overlapped with ones that the Justice Department inspector general, Michael C. Horowitz, has posed in his own look into aspects of the Russia inquiry, according to the people.
Mr. Horowitz’s report, which is most likely to be made public in the coming weeks, is expected to criticize law enforcement officials’ actions in the Russia investigation. Mr. Horowitz’s findings could provide insights into why Mr. Barr thought that the Russia investigation needed to be examined.
Mr. Durham’s questions seem focused on elements of the conservative attacks on the origins of the Russia inquiry. It is not clear whether he has asked about other parts of the sprawling probe, which has grown to include more than 2,800 subpoenas, nearly 500 search warrants, 13 requests to foreign governments for evidence and interviews of about 500 witnesses.
In his review, Mr. Durham has asked witnesses about the role of Christopher Steele, a former intelligence official from Britain who was hired to research Mr. Trump’s ties to Russia by a firm that was in turn financed by Democrats. Law enforcement officials used some of the information Mr. Steele compiled into a now-infamous dossier to obtain a secret wiretap on a Trump campaign adviser, Carter Page, whom they suspected was an agent of Russia.
The president and his supporters have vilified Mr. Steele, saying that investigators should have kept his information out of the application for the wiretap because they viewed him as having a bias against Mr. Trump. The Steele information served as one piece of the lengthy application.
They have accused the F.B.I. and Justice Department of failing to disclose that Democrats were funding Mr. Steele’s research, but the wiretap application contains a page-length explanation alerting the court that the person who commissioned Mr. Steele’s research was “likely looking for information” to discredit Mr. Trump.
Mr. Durham’s investigators asked why F.B.I. officials would use unsubstantiated or incorrect information in their application for a court order allowing the wiretap and seemed skeptical about why agents relied on Mr. Steele’s dossier.
The inspector general has also raised concerns that the F.B.I. inflated Mr. Steele’s value as an informant in order to obtain the wiretap on Mr. Page. Mr. Durham’s investigators have done the same, according to the people familiar with his review.
Mr. Horowitz has asked witnesses about an assessment of Mr. Steele that MI6, the British spy agency, provided to the F.B.I. after bureau officials received his dossier on Mr. Trump in September 2016. MI6 officials said Mr. Steele, a Russia expert, was honest and persistent but sometimes showed questionable judgment in pursuing targets that others viewed as a waste of time, two people familiar with the assessment said.
One former official said that in his interview with Mr. Durham’s team, he pushed back on the notion that law enforcement and intelligence officials had plotted to thwart Mr. Trump’s candidacy, laying out facts that prove otherwise.
For example, the former official compared the F.B.I.’s handling of its two investigations related to Mr. Trump and his 2016 opponent, Hillary Clinton. Agents overtly investigated Mrs. Clinton’s use of a private email server but kept secret their counterintelligence investigation into the Trump campaign. If the F.B.I. had been trying to bolster Mrs. Clinton’s candidacy and hurt Mr. Trump’s, they could have buried the email investigation or taken more overt steps in the Russia inquiry.
Instead, the former official noted, the opposite happened.
The former official said he was reassured by the presence of John C. Eckenrode, one of the former senior F.B.I. agents assisting Mr. Durham. Like Mr. Durham, who investigated C.I.A. torture of detainees overseas, Mr. Eckenrode is also familiar with high-stakes political inquiries.
He is probably best known for working with Patrick J. Fitzgerald, the former United States attorney who in 2003 was appointed to investigate the leak of the identity of an undercover C.I.A. officer, Valerie Plame, to a journalist.
“Jack is as straight a shooter as you can get in the F.B.I.,” Asha Rangappa, a former F.B.I. agent, said of Mr. Eckenrode, a friend. “It’s the first reassuring thing I’ve heard about this review.”
Mr. Eckenrode and Mr. Durham appear to know each other from Mr. Eckenrode’s time as agent in New Haven, Conn., where Mr. Durham has spent most of his career as a prosecutor. Mr. Eckenrode also worked in Boston and eventually ran the F.B.I.’s office in Philadelphia before retiring in 2006.
Adam Goldman reported from Washington, and William K. Rashbaum from New York.