Guccifer, whose real name Marcel-Lehel Lazar, is interviewed by the FBI as part of the FBI’s Clinton email investigation. He appears to have spoken to the FBI previously, but these may have been about other matters, since he hacked dozens of US citizens.
Around the end of April 2016, Guccifer had high-profile interviews with Fox News and NBC News. It was already known that he broke into the email account of Clinton confidant Sid Blumenthal in March 2013 and learned Clinton’s private email address. In both media interviews, Guccifer claimed that he then gained access to Clinton’s private server. But the FBI will later say that Guccifer admitted in his FBI interview that he lied about this.
Additionally, “FBI forensic analysis of the Clinton server during the timeframe [Guccifer] claimed to have compromised the server did not identify evidence that [he] hacked the server.” (Federal Bureau of Investigation, 9/2/2016)