Special counsel Robert Mueller’s team has been prodding ex-Trump campaign chairman Paul Manafort about his old consulting business partner, Roger Stone, according to a report.

Stone, a self-described political trickster and former confidant of the president, has reportedly piqued the interest of Mueller’s office for appearing to foreshadow the WikiLeaks dump of John Podesta’s emails when Podesta was Hillary Clinton’s 2016 campaign chairman. The hack is believed to have been conducted by Russian intelligence officers under the pseudonym “Guccifer 2.0.”