A fired-up Geraldo Rivera, the Fox News roaming correspondent-at-large and Fox Nation host, argued that the now-discredited FBI investigation of General Michael Flynn was indicative of a larger effort to undermine President Donald Trump.

"I think everybody now, whether they say it publically or not, recognizes that General Flynn was a good man who was absolutely set up," said Rivera on "Fox and Friends" on Friday. "He was caught in a perjury trap.  They had it as their full intent to sink him -- by hook or by crook."

The Department of Justice announced on Thursday that they were dropping the case against the former national security advisor after they determined that an FBI interview of Flynn was, "untethered to, and unjustified by, the FBI's counterintelligence investigation into Mr. Flynn" and "conducted without any legitimate investigative basis."

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Rivera, whose legendary career as an investigative journalist is captured in the Fox Nation documentary "I am Geraldo, 50 years," said that the implications of this apparent FBI attempt to take down a top White House advisor, just weeks into a new administration, can hardly be exaggerated.

"They did it to get an opening into the president of the United States," he said, "You can't understate this... this was the management, or certainly the upper-middle management of the Bureau and the Department of Justice conspiring to take down this guy because they wanted to take down the president that they thought was an illegitimate president."

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In an interview on "Fox and Friends" on Friday, President Trump reacted to the Flynn case revelations and other developments, including the release of transcripts with ex-Obama officials in 2017, during which some admitted to having no evidence of Trump-Russia collusion.

"These are dirty politicians and dirty cops and some horrible people and hopefully they're going to pay a big price in the not too distant future," Trump said.

"We can lose sight of the fact that for three years they pre-occupied this country with a phony deal," continued Rivera, "alleging essentially that the president of the United States was an agent, a spy for the Russians, whose loyalty was to Russia and not to the United States.

"We can't let them get away with that," he concluded, "We can't ever forget what they attempted to do.  Everything that followed was a result of Russia, Russia, Russia."

To hear more from Rivera and learn about his five-decade, wide-ranging career in journalism and television news watch Fox Nation's "I am Geraldo, 50 years."

In part 1 of the Fox Nation's series, Rivera re-visited the investigative reporting that revealed the sickening state of mental health care in America by exposing abuse and neglect at state-run facilities.

Now in part 2, Rivera and his producers and colleagues, like Maury Povich, looked back at the next stage of his career -- a late-night talk show that came to define an era.

On "Good Night America," Rivera would break new boundaries and interview cultural icons ranging from Muhammed Ali to Barbara Walters.

There were also dark moments, like when Rivera rushed to deliver a report on Ted Koppel's "Nightline" just hours after he personally heard the gunshots that killed John Lennon.

Watch all of this and more in part 2 of "I am Geraldo, 50 years," available right now on Fox Nation.

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Fox Nation programs are viewable on-demand and from your mobile device app, but only available only for Fox Nation subscribers. Go to Fox Nation to start a free trial and watch the extensive library from Tomi Lahren, Pete Hegseth, Abby Hornacek, Laura Ingraham, Greg Gutfeld, Judge Andrew Napolitano and many more of your favorite Fox News personalities.