WASHINGTON (Reuters) -The Russian analyst who helped compile the “Steele dossier” alleging potential ties between Donald Trump’s 2016 campaign and Russia was arrested on Thursday as part of a U.S. special counsel probe, the New York Times reported.

A lawyer for the analyst, Igor Danchenko, and Justice Department spokespeople did not immediately respond to requests for comment.

Two sources familiar with the activities of John Durham, the special prosecutor appointed by former President Trump’s Justice Department to investigate issues related to the Steele dossier, said that Durham had issued subpoenas seeking evidence from multiple sources, including people linked to Fusion GPS, the Washington, D.C. investigations firm that commissioned it.

Christopher Steele, a former British intelligence officer who prepared the dossier for Fusion GPS, which was working for a law firm that represented the Democratic Party and Hillary Clinton’s 2016 presidential campaign, declined to comment in an emailed message.

One of the sources familiar with Durham’s activities said that Fusion GPS was not a target of Durham’s investigation. Steele had previously declined here to cooperate with investigators working for Durham.

The dossier, which was circulated to the FBI and media outlets before the 2016 election, set out still-unproven allegations that Russia had embarrassing information about Trump and some of his campaign advisers and that Moscow was working behind the scenes to defeat Clinton.

In an email to Reuters a year ago, Danchenko denied he was a Russian agent, disputing suggestions by congressional allies of Trump.

“I am exactly what the Department of Justice National Security Division, the FBI, the FBI Inspector General, the Special Counsel and the Republican Senate Intelligence Committee has determined; an experienced expert in Russian affairs who has spent more than a decade in business intelligence,” Danchenko told Reuters.