Twelve years after the 9/11 attacks, the story of al-Qaeda and the US effort to stop them still has a few surprises. This one may be less than it seems, though, for reasons that the Washington Times’ Guy Taylor explains to CNN. The FBI had a mole in al-Qaeda as early as 1993, when Osama bin Laden began spitballing about a big attack on the US. Could the FBI have stopped 9/11? That’s a tougher question:

In a revelation missing from the official investigations of the Sept. 11, 2001, terrorist attacks, the FBI placed a human source in direct contact with Osama bin Laden in 1993 and ascertained that the al Qaeda leader was looking to finance terrorist attacks in the United States, according to court testimony in a little-noticed employment dispute case.

The information the FBI gleaned back then was so specific that it helped thwart a terrorist plot against a Masonic lodge in Los Angeles, the court records reviewed by The Washington Times show.

“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.

Could this have prevented the deaths of 3,000 Americans? No, Taylor says, but it did prevent an AQ attack in Los Angeles:

Youssef wasn’t the mole, though; he was the agent who ran the mole. The mole got killed in 1995 when terrorists in the AQ’s Bosnia network began to suspect he was an informant. What was he doing in Bosnia, when the FBI had him in the inner circle? The CIA had picked him up as an informant, too — stealing him from the FBI rather than coordinate efforts:

But the mole’s success had piqued the interest of another U.S. agency, the CIA. In 1994, a civilian female working for the CIA was able to convince the informant, with the help of a large sum of money, to work for the CIA instead of the FBI.

In 1994 or 1995, the CIA dispatched the informant to Bosnia, where jihadis were aiding Bosnia’s Muslim majority in a war against Serbian forces.

The FBI did not know at the time that its informant had started working for the CIA, or why he had disappeared. His former handler, Bassem Youssef, who by then was working undercover in Los Angeles as a supposed member of al Qaeda, began asking his al Qaeda sources what had become of the driver.

They told Youssef that the driver had gone to Bosnia, and that al Qaeda operatives there had killed him because they believed that he was a mole for the CIA. Later, Youssef was able to confirm that the al Qaeda operatives’ suspicions were justified, and that the driver had been working for the CIA.

So the mole was out of the loop early in the possible run-up to 9/11. Osama bin Laden carried out a number of attacks on US interests in the Middle East rather than the US itself, culminating in the USS Cole attack in 2000 before the 9/11 plot went fully operational. That’s why no one thinks the mole would have made a difference by the time the 9/11 plot became something other than aspirational:

There are two significant takeaways from this story, one of which is obvious — there is still plenty of background that we don’t know, and that wasn’t provided to the 9/11 Commission. That doesn’t mean that conspiracy theorists are any more credible, though; I don’t know of anyone who thought the 9/11 Commission got the whole story, and we may be getting nuggets like this for years. The second takeaway is that a competition between the CIA and FBI on intelligence operations can be deadly, both for key sources and for our ability to prevent attacks on American interests.