<a href="https://www.nytimes.com/2019/12/09/us/politics/who-is-john-durham-attorney.html" target="_blank" rel="noopener noreferrer">Who Is John Durham, the Prosecutor Investigating the Russia Inquiry</a>  <font color="#6f6f6f">The New York Times</font>

Mr. Durham, the top federal prosecutor in Connecticut, has investigated potential wrongdoing by the F.B.I. and C.I.A. for the Clinton, Bush, Obama and Trump administrations.

John H. Durham, United States Attorney for the District of Connecticut, in 2018. He was assigned to examine the origins of the Russia investigation.Credit…U.S. Department of Justice, via Associated Press

John H. Durham, a federal prosecutor conducting a criminal investigation into the origins of the F.B.I.’s Russia probe, said Monday that he disagreed with a report released by the Justice Department’s inspector general, which said there was no basis for President Trump’s accusation that the bureau conspired against him during the 2016 presidential election.

The report by the independent inspector general, Michael E. Horowitz, criticized the F.B.I.’s handling of a wiretap application used in the early stages of its Russia investigation, but said the bureau had adequate reason to open its investigation into the Trump campaign’s ties with Russia in 2016.

Mr. Durham is the top federal prosecutor in Connecticut and was tasked with examining the roots of the Russia investigation by Attorney General William P. Barr in May. In October, the inquiry, which began as an administrative review, was turned into a criminal investigation.

Mr. Durham has been a Justice Department lawyer since 1982, and as a career public servant has conducted special investigations under both Democratic and Republican presidents. Mr. Trump nominated him to be United States Attorney for the District of Connecticut in 2017, and he was confirmed the next year.

He has investigated potential wrongdoing by the F.B.I. and C.I.A. for the Clinton, Bush, Obama and Trump administrations.

From 2008 to 2012, Mr. Durham served as the acting United States Attorney for the Eastern District of Virginia, where he was tasked with investigating whether the C.I.A. had destroyed videotapes in 2005 that showed agents torturing terrorism suspects.

Mr. Durham’s investigation into the C.I.A. tapes was broadened a year later, during the Obama administration, by Attorney General Eric H. Holder Jr., who asked him to investigate whether the agency violated any laws in its treatments of detainees.

His first special investigation took place almost a decade earlier, during the Clinton administration.

In 1999, Attorney General Janet Reno asked him to investigate the relationship between the F.B.I. and the Boston crime boss James (Whitey) Bulger, a longtime informant. That investigation led to the prosecution of a former F.B.I. supervisory special agent and a former Massachusetts state police lieutenant, according to the Justice Department.

Mr. Durham’s assignment is the third known investigation into the counterintelligence probe opened by the F.B.I. in 2016 into possible ties between Russia’s election interference and the Trump campaign or its associates.

Mr. Durham’s role began as a limited one, but it significantly expanded when the inquiry became a criminal probe in October. That gave him the power to subpoena for witness testimony and documents, to convene a grand jury and to file criminal charges. Since then, at least two dozen former and current F.B.I. officials have been interviewed.

Mr. Barr has expressed concern about the Russia investigation in the past, saying during congressional testimony in April, “I think spying did occur.”

And in recent days, Mr. Barr has expressed skepticism of what he believed would be included in the report of the F.B.I. inspector general. On Monday, he criticized the bureau’s decision to open the Russia investigation, saying it had “launched an intrusive investigation of a U.S. presidential campaign on the thinnest of suspicions that, in my view, were insufficient to justify the steps taken.”