The extradition of Romanian hacker “Guccifer” to the U.S. at a critical point in the FBI’s criminal investigation of Hillary Clinton’s email use is “not a coincidence,” according to an intelligence source close to the case.

One of the notches on Guccifer’s cyber-crime belt was allegedly accessing the email account of Clinton confidant Sidney Blumenthal, one of Clinton’s most prolific advice-givers when she was secretary of state. It was through that hack that Clinton's use of a personal account -- clintonemail.com -- first came to light.

Former law enforcement and cyber security experts said the hacker, whose real name is Marcel Lehel Lazar, could – now that he’s in the U.S. – help the FBI make the case that Clinton’s email server was compromised by a third party, one that did not have the formal backing and resources of a foreign intelligence service such as that of Russia, China or Iran.