On Thursday, a US House committee investigating Hillary Clinton’s private e-mail server voted along party lines to hold the Democratic presidential candidate’s former IT aide in contempt of Congress.

Bryan Pagliano, the former State Department IT technician who helped set up Clinton’s private e-mail server when she was secretary of state, did not appear before the House Oversight and Government Reform Committee during its hearing investigating the server. However, Pagliano was subpoenaed.

“Subpoenas are not optional,” Committee Chairman Jason Chaffetz (R-Utah) said Thursday. “Mr. Pagliano is a crucial fact witness in this committee’s investigation of former Secretary of State Hillary Clinton’s use of a private server to conduct government business.”