A former staffer of Democratic presidential candidate Hillary Clinton has declared he will invoke the Fifth Amendment and decline to answer any questions after he was subpoenaed by the House Select Committee on Benghazi last month, according to the Washington Post.

Bryan Pagliano was identified by digital records as the person who helped set up Clinton's personal email server in 2009. He worked for Clinton during her presidential campaign in 2008 as well as the State Department.

Pagliano was asked by the Benghazi Committee, as well as the Senate Judiciary Committee and the Senate Homeland Security Committee, to testify about the server, but he refused and invoked his right against self-incrimination, according to Fox News.

A letter written by Pagliano's lawyer Mark MacDougall to Rep. Trey Gowdy, the chairperson of the Benghazi Committee, alludes to the fact that the Federal Bureau of Investigation is already looking into Clinton's private email server.

"While we understand that Mr. Pagliano's response to this subpoena may be controversial in the current political environment, we hope that the members of the Select Committee will respect our client's right," MacDougall said in the letter, according to NBC News.

Meanwhile, a Clinton campaign aide expressed in a statement the camp's disappointment at Pagliano for choosing to remain silent on the controversy and encouraged current and former aides to be helpful and more open with investigators.

Clinton is scheduled to testify before the Benghazi Committee, which is currently investigating her role in the attack of the U.S. Embassy in Libya back in 2012 that left four American nationals dead, this October, according to the International Business Times.