Special counsel Robert Mueller’s team has conducted an interview California real estate investor Tom Barrack, a confidant and longtime friend of President Trump’s, according to a new report.

Although it remains uncertain what topics specifically were covered during the questioning, one source told the Associated Press the interview solely focused on Trump’s former campaign chairman Paul Manafort and his associate, Rick Gates. Both were indicted by Mueller and Gates pleaded guilty to federal conspiracy and false-statement charges earlier this year and is complying with Mueller’s team.