"He's destroyed himself as a witness," Rudy Giuliani, President Donald Trump's attorney, said of Michael Cohen, Trump's former personal attorney. | Getty Giuliani steps up attacks on 'scoundrel' Michael Cohen

Rudy Giuliani stepped up his attacks on Michael Cohen on Sunday, saying he's "destroyed himself as a witness" in federal investigations and committed a "disbarrable offense" by recording his then-client, Donald Trump.

"The man is a pathological manipulator, a liar," Giuliani, now a personal attorney to the president, said on "Fox News Sunday."


Pressed by host Chris Wallace, Giuliani walked back comments he made in a May interview on ABC News, in which he called Cohen an "honest, honorable lawyer."

"Here's what happened: I found out, as everyone did, that he was surreptitiously recording his clients, which is a disbarrable offense," Giuliani said. "Obviously, if I knew that, I never would have said he was a reputable lawyer; I'd have said he was a scoundrel."

In light of reports that Trump's formertime attorney and fixer might cooperate with federal prosecutors, Giuliani attacked Cohen's credibility.

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"He's destroyed himself as a witness. I've prosecuted 5,000 cases. I'd never prosecute a case on this guy's testimony," Giuliani said. "He's contradicted himself so many times, you'd begin the cross-examination by saying, 'Which lies are you going to tell us today, Michael?'"

Some audio recordings seized from Cohen in an April FBI raid have been handed over to federal prosecutors, according to court filings. A nearly three-minute portion from one tape, in which Trump and Cohen discuss payments to former Playboy model Karen McDougal, was aired by CNN.