The FBI is investigating the security of Hillary Clinton's private e-mail server. Here's what we know about the server, who kept it secure and how that's changed. (Gillian Brockell/The Washington Post)

A former State Department staffer who worked on Hillary Rodham Clinton’s private e-mail server tried this week to fend off a subpoena to testify before Congress, saying he would assert his constitutional right not to answer questions to avoid incriminating himself.

The move by Bryan Pagliano, who had worked on Clinton’s 2008 presidential campaign before setting up the server in her New York home in 2009, came in a Monday letter from his lawyer to the House panel investigating the 2012 attack on the U.S. consulate in Benghazi, Libya.

The letter cited the ongoing FBI inquiry into the security of Clinton’s e-mail system, and it quoted a Supreme Court ruling in which justices described the Fifth Amendment as protecting “innocent men . . . ‘who otherwise might be ensnared by ambiguous circumstances.’ ”

The FBI is investigating whether Clinton’s system — in which she exclusively used private e-mail for her work as secretary of state — may have jeopardized sensitive national security information.

Thousands of e-mails that have been released by the State Department as part of a public records lawsuit show Clinton herself writing at least six e-mails containing information that has since been deemed classified. Large portions of those e-mails were redacted before their release, on the argument that their publication could harm national security.

Catch up on the controversy and read the emails

“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 to invoke the protections of the Constitution,” his attorney, Mark MacDougall, wrote.

Two other Senate committees have contacted Pagliano in the past week, according to a copy of the letter, which was obtained by The Washington Post. The requests came from the Senate Judiciary Committee and the Homeland Security Committee, according to people familiar with the requests.

The Senate Judiciary Committee confirmed Wednesday that it sought to ask Pagliano about his work for Clinton.

“In response to questions . . . Mr. Pagliano’s legal counsel told the committee yesterday that he would plead the Fifth to any and all questions if he were compelled to testify,” a spokesperson for committee Chairman Charles E. Grassley (R-Iowa) said in a statement.

Rep. Trey Gowdy (R-S.C.), the chairman of the House Benghazi committee, had subpoenaed the computer staffer Aug. 11 and ordered that he appear for questioning before the committee Sept. 10. Gowdy also demanded that Pagliano provide documents related to the servers or systems controlled or owned by Clinton from 2009 to 2013.

Pagliano, who worked in the State Department’s information-technology department from May 2009 until February 2013, left the agency when Clinton departed as secretary. He now works for a technology contractor that provides some services to the State Department.

The committee’s ranking Democrat, Rep. Elijah Cummings (D-Md.), complained yesterday that Gowdy unilaterally issued the subpoena. He said the subpoena of a low-level aide is one of several signs that Gowdy is using the committee for the political purpose of trying to smear a Democratic presidential candidate.

“Although multiple legal experts agree there is no evidence of criminal activity, it is certainly understandable that this witness’s attorneys advised him to assert his Fifth Amendment rights, especially given the onslaught of wild and unsubstantiated accusations by Republican presidential candidates, members of Congress and others based on false leaks about the investigation,” Cummings said. “Their insatiable desire to derail Secretary Clinton’s presidential campaign at all costs has real consequences for any serious congressional effort.”

MacDougall declined to comment late Wednesday evening.