Special counsel Robert Mueller have reportedly asked lawyers for President Trump to turn over communications logs with Roger Stone.

The request for call and visitor logs related to Stone from Trump Tower in New York came as recently as a month ago, a source briefed on the matter told CNN.

Several witnesses connected to the longtime Trump associate have given testimony to the grand jury hearing evidence in the special counsel’s investigation into Russian interference in the 2016 presidential election. At least nine people connected to Stone have been contacted by prosecutors, according to the Washington Post.

Mueller is investigating whether Stone had advance knowledge of WikiLeaks’ plans to release hacked emails stolen from Democrats, including Hillary Clinton’s campaign chairman, John Podesta.

Stone has denied coordinating with WikiLeaks and its founder Julian Assange about the release of the emails in the months before the election.

Stone attracted scrutiny from investigators after he appeared to foreshadow the release of Podesta’s emails, posting a cryptic tweet in August 2016 that said, “it will soon [be] Podesta's time in the barrel.” Then, in October 2016, WikiLeaks began publishing thousands of emails hacked from Podesta’s personal account. Stone has claimed that statement was in reference to his own investigations of Podesta and his brother, Tony.

"I never discussed any of this with Donald Trump," Stone told CNN recently. "It's one of the questions that Mr. Mueller wants the President to answer — one of the written questions. I'm highly confident that his answer will be that he knew nothing about it. We just never discussed it."

[Also read: Democrats push Jeff Sessions' replacement to protect Robert Mueller]