In Rudolph Giuliani’s narrative of his own life, as confided to rapt Republican voters along the presidential primary trail, he has been fighting the lonely twilight struggle against “Islamic terrorism” since sometime in the 1970s. Both the former mayor and his supporters often suggest that his understanding of the terror threat is visceral and almost mystical. Only he, among all the candidates of both parties, truly grasps the issue and possesses the fortitude to confront the threat.

As part of the same spiel touting his 30 years of experience battling terrorism, Giuliani often attacks the Clinton administration for failing to comprehend the nature of the problem following the first major attack on New York, which occurred shortly after he became mayor.

“Islamic terrorists killed Americans. Slaughtered Americans. Bombed the World Trade Center. Bombed it,” he said in a typical speech last summer. “You know what the reaction of the Clinton administration at the time was? It was a crime. It was another group of murders. … Well, it wasn’t just another group of murders.”

While that description of President Clinton’s response to the February 1993 bombing is hardly fair or accurate, the tone of curt disdain serves a specific partisan purpose, by warning that a Clinton restoration in the White House will endanger America. His unrelenting attacks are aimed at portraying Hillary Clinton, the Democratic front-runner, as too weak to serve as commander in chief. But his biting words also invite closer scrutiny of Giuliani’s claims about himself.

Unfortunately, few mainstream media outlets will take up that invitation. Although cable channels devote endless amounts of airtime to consider the authenticity of Mrs. Clinton’s laughter, they seem unable to cover an extraordinary scoop that raises questions about Giuliani’s authenticity.

Published in the Oct. 23 issue of The Village Voice — the New York alternative weekly that has excelled in covering the former mayor for many years — that scoop revealed the contents of his private testimony before the 9/11 Commission. The previously sealed memoranda summarizing Giuliani’s testimony, obtained by reporter Wayne Barrett, show profound contradictions between his stump speech and what he admitted to the commission behind closed doors.

For reasons that remain unclear, the minutes of his private testimony, marked “commission sensitive/unclassified,” were nevertheless to be locked away until the convenient date of December 2008. Nobody associated with the 9/11 Commission could explain how or why that decision had been made.

The Voice article discloses the embarrassing contents of a 15-page “memorandum for the record,” prepared by a commission attorney on April 20, 2004, which quotes Giuliani explaining that he knew little about Osama bin Laden’s organization until “after 9/11,” when “we brought in people to brief us on al-Qaida.” He recalled no such briefing earlier, which was “a mistake,” he acknowledged, since “if experts share a lot of info,” that would mean a “better chance of someone making heads and tails … [of the] situation.”

When a commissioner inquired about his knowledge of al-Qaida threats during the three years preceding 9/11, Giuliani replied, “At the time, I wasn’t told it was al-Qaida, but now that I look back at it, I think it was al-Qaida.” He noted that soon after the 9/11 attacks, he had brought in Yossef Bodansky, author of the prophetic 2001 book “Bin Laden: The Man Who Declared War on America,” to brief him and his staff. (In his own book, “Leadership,” he discloses that he read Bodansky’s book at the urging of his wife, and covered the text in “highlighter and notes.” No wonder he regards himself as an expert.)

Asked how he might apply the city’s crime-fighting strategies to the “war on terror,” Giuliani said, “Bernie knows more than I,” a reference to former Police Commissioner Bernard Kerik, the extremely dubious character whom he almost succeeded in installing as secretary of Homeland Security. All in all, his private testimony makes him seem clueless.

That won’t surprise anyone who has read “Grand Illusion: The Untold Story of Rudy Giuliani and 9/11,” the 2006 book by Barrett and Dan Collins that delves into many of the errors and falsehoods behind the Republican front-runner’s facade. More puzzling — but alas not so surprising — is the reluctance of the mainstream media to follow up on Barrett’s story.

When Giuliani observes that national security will be the chief concern of many voters this year and next, he is correct. That is exactly why he deserves the scrutiny he has escaped so far.

Joe Conason writes for the New York Observer.