A Russian man mentored as a political operative by Paul Manafort is coming under renewed scrutiny from special counsel Robert Mueller’s investigation into interference in the 2016 presidential election, The Guardian reports. Konstantin Kilimnik, 48, is said to have ties to the Kremlin’s intelligence services and has already been charged by Mueller with witness tampering. But Mueller is reportedly digging deeper into Kilimnik’s actions before the election with assistance from three Kilimnik associates forced to assist him as part of their plea deals: Manafort, his former deputy Rick Gates, and lobbyist Sam Patten. Nick Akerman, a former assistant special Watergate prosecutor, said: “If there’s anybody who might provide a connection between the campaign and the Russian government, it could be Kilimnik.” Kilimnik reportedly used a jet owned by sanctioned oligarch Oleg Deripaska for a trip to New York to meet Manafort in early August 2016. He was reportedly working with Manafort as early as 2004.