"[Igor] Danchenko’s identity is noteworthy because it further calls into question the credibility of the [Steele] dossier."

"By turning to Mr. Danchenko as his primary source to gather possible dirt on Mr. Trump involving Russia, Mr. Steele was relying not on someone with a history of working with Russian intelligence operatives or bringing to light their covert activities but instead a researcher focused on analyzing business and political risks in Russia.... Born in Ukraine, Mr. Danchenko, 42, [a resident of the United States] is a Russian-trained lawyer who earned degrees at the University of Louisville and Georgetown University.... He was a senior research analyst from 2005 to 2010 at the Brookings Institution....
According to his interview with the F.B.I., Mr. Steele contacted Mr. Danchenko around March 2016 and assigned him to ask people he knew in Russia and Ukraine about connections, including any ties to corruption, between a pro-Russian government in Ukraine and the veteran Republican strategist Paul Manafort. Mr. Steele did not explain why, but Mr. Manafort joined the Trump campaign around that time and was later promoted to its chairman. He was convicted in 2018 of tax and bank fraud and other charges that grew out of the Russia investigation. Mr. Steele later expanded Mr. Danchenko’s assignment to look for any compromising information about Mr. Trump. By Jan. 13, 2017, the F.B.I. had identified Mr. Danchenko, who soon agreed to answer investigators’ questions in exchange for immunity.... And Mr. Danchenko’s statements to the F.B.I. contradicted parts of the dossier, suggesting that Mr. Steele may have exaggerated the soundness of other allegations, making what Mr. Danchenko portrayed as rumor and speculation sound more solid.... The dossier [played] an important role in... the wiretapping of Carter Page, a former Trump campaign adviser with close ties to Russian officials, which began in October 2016 and was extended three times in 2017. The Justice Department’s applications for court orders authorizing the wiretap relied in part on information from the dossier in making the case that investigators had reason to believe that Mr. Page might be working with Russians....  [L]aw enforcement officials recycled the same language derived from the dossier in their final two applications for court orders to continue wiretapping Mr. Page. They also told a court they had spoken to Mr. Steele’s primary source but without revealing that his statements raised questions about the dossier’s credibility."

From "The F.B.I. Pledged to Keep a Source Anonymous. Trump Allies Aided His Unmasking/After a Russia expert who had collected research on Donald Trump for a disputed dossier agreed to tell the F.B.I. what he knew about it, law enforcement officials declassified a road map to identifying him" (NYT).