A former aide to Hillary Clinton, who helped set up her private email server, has told at least three congressional committees that he will invoke the Fifth Amendment to avoid testifying against his former boss.

Bryan Pagliano, who worked on Clinton's 2008 presidential campaign before helping install her private server system in her New York home, declined to testify about the server before the House Select Committee on Benghazi, the Senate Judiciary Committee and the Senate Homeland Security Committee.

On "Special Report" tonight, Charles Krauthammer said that it is logical to assume that Pagliano invoked the Fifth Amendment to avoid contradictory testimony and perjury.

"For example, if you ask him, 'What were you told? What did the secretary say she wanted? Did she give you a reason? What was hidden in here that we don't know?'" Krauthammer explained. "All of these things, he'd rather not have to say, because you can be sure there would be contradictory testimony."

Krauthammer said he believes that Pagliano will eventually be given immunity for his testimony, but investigators are waiting to gather testimony from others first, so they'll better know what questions to ask him.

"I think it's a good thing to wait, and then you give him immunity, and you get the story."

Watch more from the "Special Report" panel above.

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