Massoud and Makowski’s relationship deepened, and eventually Massoud offered Makowski access to the extensive intelligence network he’d built while fighting Soviet occupation in the 1980s and carried on after the Taliban ousted the regime of Burhanuddin Rabbani, in which Massoud was the defense minister.

Soon Makowski was focused on bin Laden.

“There was a period of 12 months when we were tracking bin Laden basically day to day,” he told McClatchy. He said he’d supplied the Polish intelligence services with “everything Massoud’s service had on al Qaida, on bin Laden and on the Taliban structures.” The Polish service passed the information to the CIA, which sent “tons” of follow-up questions, Makowski said.

Makowski thinks that was why Massoud granted him the access to his network in the first place.

But the CIA didn’t warm to Massoud, Makowski said, and it’s unclear whether the information reached all the CIA analysts who were monitoring bin Laden. Scheuer, for one, said he couldn’t recall “hearing of any information from a Polish government source on al Qaida." He added, "I know that period pretty well."

Makowski now thinks that Massoud held back intelligence about bin Laden and the 9/11 plot because of the CIA’s lack of interest. “I am aware of the fact that the development of modern Afghanistan doesn’t matter to the Americans,” Makowski recalls Massoud telling him in August 1999.

He knew, however, that the United States was interested in bin Laden, and he feared that if bin Laden were killed, the U.S. would reach an accommodation with the Taliban. He decided to play it coy, Makowski says. “I will stall for time until I make sure they had stopped supporting the Taliban and are ready to support me instead," Makowski said Massoud had concluded.

In mid-June 2000, Massoud practically ordered his commanders not to cooperate with the CIA in hunting down bin Laden. Makowski thinks Massoud also avoided telling the Americans of bin Laden’s plan for the 9/11 strikes.

“I think there is a very good case that he allowed this to happen,” Makowski told McClatchy, speaking of 9/11.

Unfortunately, Massoud missed a key part of bin Laden’s 9/11 planning: Massoud’s own assassination, which took place on the eve of the Sept. 11 attack.

“If it were not for his death days before, all the pieces would have fallen into place, and Massoud would have been returned to power," Makowski says, referring to the U.S.-led post-9/11 campaign that swept the Taliban from power.

How did Massoud, the master of intelligence in Afghanistan, fail to spot the assassination plot against him?

“Intelligence failure,” Makowski said. “You have those things even in the best intelligence service."

Jonathan S. Landay in Washington and McClatchy special correspondent Barbara Dziedzic in Warsaw contributed to this report.