Washington(CNN) Jerome Corsi, a prominent conspiracy theorist with ties to Roger Stone, was subpoenaed to testify before a federal grand jury Friday as part of special counsel Robert Mueller's Russia investigation, according to Corsi's attorney.
But Corsi's appearance was postponed after he met with Mueller's investigators for hours Thursday afternoon for a voluntary interview ahead of his scheduled grand jury appearance. His attorney, David Gray, would not comment on what Corsi was asked about during his voluntary interview or why the grand jury appearance was postponed. It may be rescheduled for a later date, he said.
"We are going to be fully cooperative. We have nothing to hide," Gray told CNN when the news of the subpoena was first reported by The New York Times earlier this week. "While we believe the focus will be on his communications with Roger Stone, that is an assumption."
Corsi had been one of the latest in a string of Stone associates to be summoned by Mueller's team. Randy Credico, a comedian who's another former associate of Stone's, was also slated to appear before the grand jury Friday and did so.
Stone, a longtime political adviser to President Donald Trump, attracted scrutiny in 2016 after claiming to have a back channel to WikiLeaks and appearing to predict that the site would release damaging information related to Hillary Clinton during the presidential campaign. Stone has since said he had no contact with Julian Assange, the founder of WikiLeaks. Meanwhile, US intelligence agencies concluded that Russian intelligence had hacked Democratic targets and used WikiLeaks to spread that material online.
In summer 2016, Stone tweeted that it would soon be "Podesta's time in the barrel," which was later seen as an indication Stone may have had advance warning that then-Clinton campaign chairman John Podesta's hacked emails would soon be public.
In March 2017, Corsi -- the former DC bureau chief for the fringe website InfoWars -- wrote a piece explaining that he had been the source for the seemingly prescient tweet by Stone. In his article, Corsi wrote that his own research had inspired Stone's tweet.
Stone has since said he was referring to both DC lobbyist Tony Podesta and then-Clinton campaign chairman John Podesta, and their business dealings.
Corsi, a birther who reportedly helped fuel Trump's long-held belief that former President Barack Obama wasn't born in the US, first came up in the Mueller probe through another associate, Ted Malloch. Malloch -- a professor, author and Trump ally -- said FBI agents had questioned him about topics including Corsi, Stone and WikiLeaks as part of the Mueller investigation, according to an interview Malloch did with NBC News.
Gray, Corsi's attorney, said his client had no communication with Assange, WikiLeaks or Guccifer 2.0, the online persona that US intelligence says was controlled by Russian hackers..
"There's nothing that even hits of any criminal liability on his part," Gray said of Corsi.
While Mueller's investigators appear to be circling Stone, Stone said he still has not been contacted by the special counsel. He has said he had no prior knowledge of the hacked emails and was not involved in any collusion efforts related to the 2016 campaign.