Judge Andrew Napolitano reacted to news that the Justice Department granted immunity to a key witness in the Hillary Clinton email scandal.

“Hillary should be terrified,” of the fact that a former staff member could testify to a Grand Jury in the investigation said the Fox News senior judicial analyst on “Varney & Co,” Thursday.

Former State Department staffer, Bryan Pagliano, who set up the private email server in Clinton’s New York home in 2009, has been granted immunity because the lawyers in the Justice Department want to call him as a witness to testify against someone in a position higher than his, Napolitano explained.

“Mr. Pagliano is their nightmare,” the judge noted, in response to a statement from the Clinton camp that said the Democratic candidate encouraged the former staffer who had no reason “to not be transparent.”

“They are out of their minds,” Napolitano said. “That is a response written by their political people and not by their legal people.”

The judge did not know how long it would be before the investigation results become public. “But if you were a Democrat,” he said, “wouldn’t you want to know if Mrs. Clinton was going to be exposed to criminal prosecution before you completed the nomination process?”

Appearing earlier on “Fox & Friends,” Napoiltano said an indictment against Clinton “will change the picture dramatically and radically” of the Democratic presidential race.

“It will shake the Democratic Party and the American political establishment to the core,” he said.

Watch Napolitano’s comments in the Fox Business video below.