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Jerome Corsi, a conspiracy theorist with links to both ex-Trump aide Roger Stone and Infowars host Alex Jones, has been subpoenaed to testify before a federal grand jury in Washington, D.C., Friday as part of special counsel Robert Mueller’s probe, his attorney says.

Jerome Corsi holds a copy of his book "Where's the Birth Certificate?" during a book signing at Book Expo America in New York on May 25, 2011. Charles Sykes / AP file

Corsi, who has written such books as "Where’s the Birth Certificate?" and "Killing the Deep State: The Fight to Save President Trump" will fully comply with the Mueller team’s subpoena, according to attorney David Gray.

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The subpoena was first reported by the New York Times.

Gray told NBC News he expects his client will be questioned about his contacts and communications with Stone.

Questions have long swirled about Stone's possible interactions with WikiLeaks and hacker Guccifer 2.0 during the 2016 campaign, when both entities were releasing Democratic emails that had been hacked by Russian intelligence agents.

Stone has denied any wrongdoing, and says he had no advance knowledge of hacked emails.

Gray also says Corsi will bring his computer and cell phone to Washington as part of his effort to cooperate with the special counsel.

Corsi’s name first came up in the probe in March. As first reported by NBC News, Trump ally and Corsi associate Ted Malloch was detained at Boston’s Logan Airport and questioned by the FBI.

Malloch said federal agents questioned him about Stone, Corsi and WikiLeaks. Malloch said he told them he met Stone a total of three times and always with groups of people, and that Corsi had helped edit one of his books years ago.

A spokesperson for the special counsel’s office declined to comment.

Corsi became the D.C. bureau chief for Infowars in 2017, but no longer works there. Prior to the 2016 presidential election he was a source for Trump's incorrect claims that Barack Obama was not born in the U.S.