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Fox News chief intelligence correspondent Catherine Herridge reports that the FBI is investigating whether Hillary Clinton's aides shared passwords to access classified information.

Herridge said the FBI is probing how information from secure government computer systems made its way to Clinton's unsecured server.

She likened the allegation to a CEO giving his or her email password to an assistant in order to handle communications. 

Earlier today, we learned that a potential key witness was just granted immunity by the Justice Department.

Bryan Pagliano is a former State Department staffer who set up the email server in Clinton's New York home in 2009.

Herridge said it's possible that Pagliano had administrative privileges and "physically moved" data between the systems. 

Watch Catherine explain further in the report above.

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