WASHINGTON — Federal authorities on Thursday arrested an analyst who in 2016 gathered leads about possible links between Donald J. Trump and Russia for what turned out to be Democratic-funded opposition research, according to people familiar with the matter.
The arrest of the analyst, Igor Danchenko, is part of the special counsel inquiry led by John H. Durham, who was appointed by the Trump administration to scrutinize the Russia investigation for any wrongdoing, the people said.
Mr. Danchenko, was the primary researcher of the so-called Steele dossier, a compendium of rumors and unproven assertions suggesting that Mr. Trump and his 2016 campaign were compromised by and conspiring with Russian intelligence officials in Moscow’s covert operation to help him defeat Hillary Clinton.
The people familiar with the matter spoke on condition of anonymity because the indictment of Mr. Danchenko had yet to be unsealed. A spokesman for Mr. Durham did not respond to a request for comment.
Some claims from the Steele dossier made their way into an F.B.I. wiretap application targeting a former Trump campaign adviser in October 2016. Other portions of it — particularly a salacious claim about a purported sex tape — caused a political and media firestorm when Buzzfeed published the materials in January 2017, shortly before Mr. Trump was sworn in.
But most of the important claims in the dossier — which was written by Mr. Danchenko’s employer, Christopher Steele, a former British intelligence agent — have not been proven, and some have been refuted. F.B.I. agents interviewed Mr. Danchenko in 2017 when they were seeking to run down the claims in the dossier.
The interview suggested that aspects of the dossier were misleading: Mr. Steele left unclear that much of the material was thirdhand information, and some of what Mr. Danchenko — who was born in Russia but lives in the United States — had relayed was more speculative than the dossier implied.
A 2019 investigation by the Justice Department’s inspector general sharply criticized the F.B.I. for continuing to cite material from the dossier after the bureau interviewed Mr. Danchenko without alerting judges that some of what he said had cast doubt on the contents of the dossier.
The inspector general report also said that a decade earlier, when Mr. Danchenko worked for the Brookings Institution, a prominent Washington think-tank, he had been the subject of a counterintelligence investigation into whether he was a Russian agent.
In an interview with The New York Times in 2020, Mr. Danchenko defended the integrity of his work, saying he had been tasked to gather “raw intelligence” and was simply passing it on to Mr. Steele. Mr. Danchenko — who made his name as a Russia analyst by exposing indications that the dissertation of President Vladimir V. Putin of Russia contained plagiarized material — also denied being a Russian agent.
“I’ve never been a Russian agent,” Mr. Danchenko said. “It is ridiculous to suggest that. This, I think, it’s slander.”
Mr. Steele’s efforts were part of opposition research that Democrats were indirectly funding by the time the 2016 general election took shape. Mr. Steele’s business intelligence firm was a subcontractor to another research firm, Fusion GPS, which in turn had been hired by the Perkins Coie law firm, which was working for the Hillary Clinton campaign.
Mr. Danchenko said he did not know who Mr. Steele’s client was at the time and considered himself a nonpartisan analyst and researcher.
Mr. Durham has been known to be interested in Mr. Danchenko and the Steele dossier saga. In February, he used a subpoena to obtain old personnel files and other documents related to Mr. Danchenko from the Brookings Institution, where Mr. Danchenko had worked from 2005 until 2010.
The charges against Mr. Danchenko follow Mr. Durham’s indictment in September of a cybersecurity lawyer, Michael Sussmann, which accused him of lying to the F.B.I. about who he was working for when he brought concerns about possible Trump-Russia links to the bureau in September 2016.
Mr. Sussmann, who then also worked for Perkins Coie, was relaying concerns developed by data scientists about odd internet logs they said suggested the possibility of a covert communications channel between the Trump Organization and Alfa Bank, a Kremlin-linked financial institution. He has denied lying to the F.B.I. about who he was working for.
William K. Rashbaum contributed reporting.