Roger Stone, a longtime ally of President Trump, speaks to reporters after appearing before a closed House Intelligence Committee hearing in September 2017. (Kevin Lamarque/Reuters)

Conservative political commentator Jerome Corsi is set to appear Friday before the grand jury investigating evidence in special counsel Robert S. Mueller III’s probe of Russian interference in the 2016 campaign and expects to be questioned about his communications with Roger Stone, a longtime adviser to President Trump.

Corsi’s attorney, David Gray, confirmed that Mueller’s team served Corsi with a subpoena last week and that Corsi plans to cooperate.

Corsi, who has contributed to the right-wing website Infowars and is known for promoting political conspiracy theories, provided research to Stone during the 2016 campaign.

Gray said the subpoena indicated that Mueller is interested in Corsi’s communications during 2016 and 2017. Gray said he believes the special counsel plans to ask about Corsi’s contacts with Stone, who has come under intense scrutiny by Mueller’s investigators.

Corsi shared research with Stone around the same time that the longtime GOP consultant claimed publicly that he had been in contact with WikiLeaks founder Julian Assange and had advance knowledge of WikiLeaks’ releases of hacked Democratic emails.

Stone has since denied direct contact with Assange and said he had no specific knowledge of WikiLeaks’ material or the group’s plans to release it.

Gray said Corsi had no contacts with WikiLeaks. He would not comment on what Corsi’s communications indicate about Stone or his interactions with WikiLeaks.

“They show communication,” Gray said. “I’m not going to make any comments about what the special counsel’s office thinks of Roger Stone’s communications.”

Gray said he was confident that Corsi has done nothing wrong. “Jerry Corsi made decisions that he would not take actions that would give him criminal liability,” he added, declining to elaborate.

Asked if Corsi had opportunities to take such actions, Gray said, “I wouldn’t say he was offered those opportunities. I would say he had communications with Roger Stone. We’ll supply those communications and be cooperative. My client didn’t act further that would give rise to any criminal liability.”

Gray said that Corsi plans to bring his laptop and cellphone with him to the grand jury and make them available to investigators. Corsi’s subpoena was first reported by the New York Times.

Randy Credico, a New York radio host who Stone has said was his conduit to communications with WikiLeaks, is also set to appear in front of the grand jury Friday.

In response to a request for comment on Corsi’s subpoena, Stone said that Corsi “has already addressed these issues in his own voice.” He pointed to a March 2017 Infowars column in which Corsi said that he conducted research about Democratic presidential candidate Hillary Clinton, her campaign chairman, John Podesta, and Russia in the final weeks of the 2016 campaign.

In the column, Corsi speculated that his research might have caused Stone to tweet on Aug. 21, 2016, “Trust me, it will soon [be] Podesta’s time in the barrel.”

That tweet came about six weeks before WikiLeaks began posting caches of Podesta’s hacked emails.

Stone has also said his tweet was spurred in part by Corsi’s research, telling the House Intelligence Committee in September that it was “based on a comprehensive, early August opposition research briefing” that Corsi provided him.

Stone has said that he did not know WikiLeaks had Podesta’s emails.

Stone also had communications in 2016 with Guccifer 2.0, the online persona that prosecutors have said was operated by the Russian intelligence units they said hacked the Democratic Party and Podesta. Stone has said the contacts were innocuous, and denied knowing Guccifer 2.0 was tied to Russian intelligence.

Mueller’s team has been scrutinizing Stone for months. This summer, a series of other Stone associates have been interviewed or asked to appear before the grand jury.

One Stone aide, Andrew Miller, has been held in contempt of court for refusing to comply with a grand jury subpoena and is seeking to have Mueller’s investigation declared unconstitutional.

Manuel Roig-Franzia contributed to this report.