Today on Fox News' America Live, Megyn Kelly offered repeated tension-filled teases for an interview with a “former DOJ official” who she promised would explain how the White House “had to know” about the controversial tactics used in the ATF's failed Operation Fast and Furious and would provide “his take on what Mr. [Attorney General Eric] Holder likely knew and when he knew it.” But Kelly's big get wasn't someone with any actual knowledge of the operation or its aftermath, but rather Andrew C. McCarthy, the resident anti-Obama conspiracy theorist at the right-wing National Review.

McCarthy's credentials to make broad claims about what the White House and senior DOJ officials would be limited even if his credibility was not; he served as an Assistant U.S. Attorney in New York, not at DOJ headquarters in Washington, DC, and left public service in 2003.

But McCarthy's credibility certainly is in question. While McCarthy first gained fame for prosecuting the 1993 World Trade Center bombing, in recent years he has become known for his viciously anti-Muslim rhetoric and adoption of conspiracy theories.

In a 2011 New Republic post calling McCarthy a “walking clearinghouse of right-wing conspiracies,” Jonathan Chait noted that McCarthy has written:

Obama's radicalism, beginning with his Alinski/ACORN/community organizer period, is a bottom-up socialism. This, I'd suggest, is why he fits comfortably with Ayers, who (especially now) is more Maoist than Stalinist. What Obama is about is infiltrating (and training others to infiltrate) bourgeois institutions in order to change them from within -- in essence, using the system to supplant the system. A key requirement of this stealthy approach (very consistent with talking vaporously about “change” but never getting more specific than absolutely necessary) is electability.

McCarthy has also:

• Used his platform at National Review's The Corner blog to question whether Bill Ayers was the true author of President Obama's 1995 memoir Dreams From My Father, citing Jack Cashill's flawed analysis. He subsequently doubled down on the theory after National Review colleague Jonathan Adler criticized the hypothesis as “outlandish” and “nutter-territory stuff.”
• Written a book that invoked numerous smears and falsehoods in order to make the case that President Obama has “Islamist sympathies” and “seem[s] disposed” to “advance the cause of Islam in the world.” McCarthy also suggested that Obama's 1981 visit to Pakistan could indicate that he was “a citizen of an Islamic country.”
• Dissented from a National Review editorial criticizing birtherism by questioning the significance of the birth certificate Obama released in 2008 and speculating that Obama may be a “Muslim citizen of Indonesia.”

• Attacked DOJ lawyers who previously defended terrorism suspects as having “work[ed] for the enemy.”
• Pushed the myth that at an event is 2007, Obama “marched with members of the New Black Panther Party.”
• Dissented from a National Review editorial denying the existence of “death panels” in health care reform, writing that “Palin was right.”
• Declared that “what 'radicalizes' Muslims is Islam -- the mainstream interpretation of it.”
• Pushed a baseless conspiracy theory that Obama gave Interpol broad powers to investigate U.S. citizens without being limited by the Constitution.
• Wrote that The New York Times “sided with al Qaeda” by publishing an article describing a secret Bush administration program designed to monitor international financial transaction.