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.