Special counsel Robert Mueller’s office has questioned witnesses and obtained evidence regarding longtime Trump adviser Roger Stone’s interactions with WikiLeaks, The Wall Street Journal reports. Investigators have reportedly obtained phone records in their pursuit to find out whether Stone had advance knowledge of WikiLeaks’ release of Hillary Clinton’s hacked campaign emails. Right-wing figure Jerome Corsi, former Trump campaign staffer Sam Nunberg, and New York radio host Randy Credico have also been questioned by Mueller’s office about Stone’s interactions with WikiLeaks, according to the report. Mueller’s office reportedly has evidence that Peter W. Smith, the late GOP activist who sought Clinton’s emails, may have had “advance knowledge of details about the release of emails” by Wikileaks. Stone’s interactions with WikiLeaks is under scrutiny after he publicly predicted the Clinton leaks and indicated he had communicated with Guccifer 2.0—who was later revealed to be an officer of Russia’s military intelligence directorate.