Barry Bennett, a senior adviser to the Donald Trump campaign, blasted Democratic front-runner Hillary Clinton over the current FBI inquiry into her private email server use, calling the former state secretary a liar and saying that she has "stonewalled" the investigations.

"She has continued to lie about it, right?" Bennett said in an interview with CNN Friday regarding Clinton's email controversy. "She told us the lawyers signed off on it, the inspector general said that's not true."

"She said she would cooperate with all of the investigations. She stonewalled the IG and now everybody's taking the Fifth," Bennett continued, referring to recent news that Clinton's former tech aide, who helped set up the private server, would invoke his Fifth Amendment right in a deposition in the Judicial Watch case.

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Then the Trump adviser added: "You couldn't get the truth from Hillary Clinton if you waterboarded her."

CNN host Kate Bolduan did a double take at the statement: "What?!"

Bennett reiterated his assertion, saying "You couldn't get the truth out of her with a waterboard."

Trump said Thursday that he believed Clinton should go to jail over her emails, launching the attack at a California rally shortly after the former secretary of state swiped at Trump's own foreign policy credentials in a speech focused on national security.

"After what she said about me today and her phony speech. That was a phony speech. That was a Donald Trump hit job," Trump told a rally in San Jose. "I will say this: Hillary Clinton has to go to jail. She has to go to jail."

In the past, Trump has endorsed the use of torture techniques like waterboarding against enemies like the Islamic State of Iraq and Syria (ISIS), promising to relax laws to allow it.

"I happen to think that we should use something that's stronger than we have right now," Trump told CBS' "Face the Nation" back in March. "Right now, basically, waterboarding is essentially not allowed, as I understand it. ... I would certainly like it to be, at a minimum, at a minimum to allow that."