A Department of Justice decision to grant immunity to Hillary Clinton’s top IT aide indicates officials are “considering potential criminal charges” against the former secretary of state or her aides, according to a source familiar with the investigation.

The immunity was reportedly given to Bryan Pagliano, Clinton’s 2008 presidential campaign IT director, who followed her to the State Department in 2009. He received a politically-appointed position from which he managed the unsecured private home-brew email server Clinton used throughout her tenure as the nation’s chief diplomat instead of secured government computer channels.

“Giving him immunity” indicates “they are considering potential criminal charges against people higher up in the chain,” said the source who requested anonymity because he is not authorized to discuss the investigation with reporters.

More than 2,000 emails containing classified information was sent to and from Clinton via the unsecured server that IT experts believe was almost certainly compromised by hackers working for foreign powers like Russia and China.

Brigadier General Kenneth Bergquist, a former high-ranking intelligence and special operations official who is now a practicing attorney, told The Daily Caller News Foundation that Clinton and some of her aides face the prospect of multiple federal charges, including “knowingly” concealing operation of the private server from State Department security officials, as well as a public corruption charge of “honest services fraud.”

Honest services fraud is generally easier to prove because the charge includes unethical conduct by public officials, Bergquist said. Bergquist was appointed as the first president of the Joint Special Operations University by the Chairman of the Joint Chiefs of Staff in 2001 after a career in intelligence and counter-terrorism.

The Inspector General for the Intelligence Community informed Congress that classified materials on her server included those ranked “Top Secret” and an even higher classification called “Special Access Programs.”

FBI Director James Comey told a House Judiciary Committee hearing Tuesday that he is “very close personally” to the Clinton investigation.

[dcquiz] Lt. General Mike Flynn, President Barack Obama’s former Defense Intelligence Agency director, told TheDCNF February 10, that Clinton should leave the presidential race and step down as a candidate until the FBI investigation is closed.

”I think Hillary Clinton, for the good of the country, should step down and let this FBI investigation play out,” Flynn said.

Tom Fitton, the president of Judicial Watch, which forced the State Department to release 55,000 pages of her emails under a Freedom of Information Act lawsuit, said the Pagliano turn of events “is a major development. This is the first confirmation that a witness is communicating with the Justice Department and the FBI about Mrs. Clinton’s conduct and about her system.”

Follow Richard on Twitter

Content created by The Daily Caller News Foundation is available without charge to any eligible news publisher that can provide a large audience. For licensing opportunities of our original content, please contact licensing@dailycallernewsfoundation.org.