The information the FBI gleaned back then was so specific that it helped thwart a terrorist plot against a Masonic lodge in Los Angeles, according to a court testimony in a little - noticed employment dispute case cited by The Washington Times.
"It was the only source I know in the bureau where we had a source right in al-Qaeda, directly involved," Edward J Curran, a former top official in the FBI's Los Angeles office, told the court in support of a discrimination lawsuit filed against the bureau by his former agent Bassem Youssef.
Curran gave the testimony in 2010 to an essentially empty courtroom, and thus it escaped notice from the media or terrorism specialists.
The Times was recently alerted to the existence of the testimony while working on a broader report about al-Qaeda's origins.
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Members of the September 11 commission, congressional intelligence committees and terrorism analysts told daily they are floored that the information is just now emerging publicly and that it raises questions about what else Americans might not have been told about the origins of al- Qaeda and its early interest in attacking the United States.
Exactly how the information was omitted from the various congressional reviews and the 9/11 Commission report is a mystery, the report said.
As the case played out in federal court in 2010, Curran testified in Youssef's favour, methodically telling the court about the agent's many successes during the early 1990s when the US government's unofficial war on terrorism was just beginning.
The former supervisor testified that Youssef developed a confidential source connected to the infamous "Blind Sheik," Omar Abdel-Rahman, the mastermind of the 1993 World Trade Center bombing, and that he managed to send that source overseas and meet personally with bin Laden.
The source was very close to the leadership of al-Qaeda, which was then known as the Islamic Group. The one source came back, had direct contact with bin Laden, Curran testified.
Eventually, the plot to blow up the Los Angeles target was diffused based on information the source provided the FBI, according to the court testimony and other FBI documents.