Mark Rossini [was] a high-flying FBI official in Washington a decade ago, when he was a special assistant to the bureau's chief spokesman. A boneheaded move ... cost him his career in 2008. He's making a determined effort ... to close some of the gaping holes in the official 9/11 narrative. Rossini [has] been at the center of one of the enduring mysteries of 9/11: Why the CIA refused to share information with the FBI ... about the arrival of at least two well-known Al-Qaeda operatives in the United States in 2000, even though the spy agency had been tracking them closely for years. The CIA did block him and Doug Miller, a fellow FBI agent assigned to the ... CIA's Osama bin Laden unit, from notifying bureau headquarters about the terrorists. Rossini and Miller [had] learned earlier from the CIA that one of the terrorists (and future hijacker), Khalid al-Mihdhar, had multi-entry visas on a Saudi passport to enter the United States. When Miller drafted a report for FBI headquarters, a CIA manager in the top-secret unit told him to hold off. Incredulous, Miller and Rossini had to back down. Years later, Rossini still regrets complying with that command. If he had disobeyed the gag order, the nearly 3,000 Americans slaughtered on 9/11 would probably still be alive. The CIA has long insisted it shared intelligence about [this] with the FBI, but records gathered by the 9/11 Commission contradict this assertion. No one has come up with a plausible explanation. When the first 9/11 report came out ... all the people who were responsible for not sharing information [had] their names ... taken out. They were commended and moved up.