A New York radio host and longtime associate of the political consultant Roger J. Stone Jr. was subpoenaed by a federal grand jury hearing evidence in the Russia investigation, his lawyer said on Friday.
The radio personality, Randy Credico, who hosts a political talk show out of New York City and has been a perennial, if unsuccessful, candidate for office in New York, is expected to give testimony to the grand jury on Sept. 7, according to the lawyer, Martin Stolar.
Mr. Stolar said he suspected that prosecutors from the office of the special counsel, Robert S. Mueller III, wanted to ask Mr. Credico about Mr. Stone’s dealings with Russian hackers and WikiLeaks, though he cautioned that he was simply speculating.
“That’s the only thing that I can conceive of that Randy would have anything to talk to them about,” Mr. Stolar said.
Mr. Stone, a veteran adviser to President Trump, is a key focus of the special counsel’s investigation into whether anyone on Mr. Trump’s campaign worked with the Russian operatives who were secretly trying to tip the election in Mr. Trump’s favor. Mr. Stone is central to that question because he appeared to have advance knowledge of the moves that Russian hackers were making.
Mr. Stone said in a speech that he had “communicated with” Julian Assange, the founder of the anti-secrecy group WikiLeaks, and predicted that a trove of information about Hillary Clinton would be published before the election. And on Twitter, he seemed to correctly predict the release of emails — stolen by Russian hackers — sent and received by John D. Podesta, Mrs. Clinton’s campaign chairman.
“Trust me, it will soon the Podesta’s time in the barrel,” Mr. Stone wrote on Twitter.
At least two campaign officials — Mr. Trump’s eldest son and a foreign policy adviser, George Papadopoulos — were aware of the Russian government’s interest in assisting the Trump campaign and were eager to receive the help. Mr. Trump said nothing ever came of those efforts. Mr. Stone’s predictions have raised questions about whether the campaign did have secret ties to the Russian hacking effort.
Mr. Credico’s connection to the Russia investigation came circuitously. Last year, he was identified as the intermediary between Mr. Stone and Mr. Assange, whose organization was instrumental in releasing Democratic emails and other internal documents that proved damaging to Mrs. Clinton’s presidential bid.
Mr. Mueller’s team recently unsealed an indictment charging that Russian intelligence officers using the online avatar Guccifer 2.0 stole the documents and funneled them to WikiLeaks. A person “in regular contact with senior members” of Mr. Trump’s campaign had communicated with Guccifer 2.0, the indictment said. Government officials have identified that person as Mr. Stone.
Mr. Stone said in a statement that he did not know ahead of their publication where the WikiLeaks documents had come from or what they contained.
“At no time did Mr. Credico tell me what the source, content or scope of the WikiLeaks disclosures would be,” he said. “I would note that Mr. Credico has avoided testifying on these matters under oath. If he is compelled to testify, I would urge Mr. Credico to simply tell the truth.”