Convicted former Trump campaign chairman Paul Manafort is being questioned by special counsel Robert Mueller’s team about ex-business partner and friend Roger Stone, ABC News reported Wednesday.

Stone, a longtime ally of President Donald Trump and a onetime partner with Manafort at the lobbying firm Black, Manafort, Stone and Kelly, has come under increasing scrutiny by the Mueller team, the news outlet noted. 

And Manafort’s status as a cooperating witness now opens him to questioning about the Trump ally as well, the news outlet reported.

According to ABC News, nearly a dozen individuals close to Stone have been brought in for interviews by the special counsel’s investigators, and many of those same people have gone before a federal grand jury.

Mueller’s interest in Stone appears to be focused on whether he or his associates communicated with Julian Assange or WikiLeaks about the release of damaging emails allegedly hacked from Hillary Clinton’s campaign by Russian intelligence officers masquerading as hacker persona “Guccifer 2.0,” ABC News reported.

Stone, for his part appears unfazed by the questioning of Manafort, telling ABC News it “certainly wouldn’t be surprising” given he and Manafort “have been friends since childhood.”

“I am highly confident Mr. Manafort is aware of no wrong doing on my part during the 2016 campaign, or at any other time, and therefore there is no wrongdoing to know about,” Stone told ABC News. “Narratives to the contrary by some in the media are false and defamatory.”

Stone also seems resigned to the possibility he is one of Mueller’s next targets.

“It’s not outside the realm of possibility,” Stone previously told ABC News, “that [Mueller] may consider bringing some offense against me.”

Manafort has pleaded guilty to two counts of conspiracy in Washington, D.C., and is awaiting sentencing on 18 counts of financial crimes in Virginia.