The case against Igor Danchenko is part of special counsel John Durham's ongoing investigation into the origins of the FBI's probe into whether Trump's 2016 campaign and Russia had conspired to tip the outcome of that year's presidential campaign.

The indictment, the third criminal case brought by Durham and the second in a two-month span, is likely to boost complaints from Trump allies that well-connected Democrats worked behind the scenes to advance suspicions about Trump and Russia that contributed to the FBI's election-year investigation.

The case does not undercut investigators' findings that the Kremlin aided the Trump campaign — conclusions that were not based on the dossier, which was barely mentioned in special counsel Robert Mueller's report. But the indictment does endorse a longstanding concern about the Russia probe: that opposition research the FBI relied on as it surveilled a Trump campaign adviser was marred by unsupported, uncorroborated claims.