The employee who helped set up and manage Hillary Clinton's private email server for her work as secretary of state no longer works at the State Department, a department spokesman said on Thursday.

Bryan Pagliano is cooperating with the Federal Bureau of Investigation's criminal inquiry into the email setup in exchange for immunity from prosecution by the U.S. Department of Justice, according to the Washington Post.

The investigation has clouded Hillary Clinton's campaign to become the Democratic Party's candidate in the November presidential election. Clinton has apologized for the arrangement but says that she did nothing wrong and that she believes the government will vindicate her.

In September, the State Department said Pagliano still worked at the department's Bureau of Information Resource Management as a contractor.

On Monday, department spokesman John Kirby told reporters Pagliano had stopped working there, but declined to say when or why.

Pagliano previously worked on Clinton's failed 2008 presidential campaign, and ended up joining her at the State Department in 2009 as a political appointee, working as a technology specialist and maintaining the email server kept in Clinton's New York home. His employment ended with Clinton's in February 2013, but he stayed on as a contractor.

More than 2,000 of Clinton's emails contain classified information that could harm national security if leaked, according to the State Department. The government forbids sending or storing such information outside secure, government-controlled channels.

The FBI and the Justice Department have declined comment on their investigation, including who might be its target, beyond confirming its existence.

Pagliano's lawyer did not respond to requests for comment. A Clinton spokesman said the campaign is pleased that Pagliano is cooperating, but declined to respond to questions.

For more on the 2016 presidential race, see the Reuters blog, "Tales from the Trail" (blogs.reuters.com/talesfromthetrail/)