WASHINGTON – From Afghanistan to Europe to the U.S. Midwest, suspected terrorists, often beating a hasty retreat from their homes, camps and caves, have left behind a mountain of suspicious items that U.S. investigators are combing for clues.
Information in some discovered documents has led to arrests, thwarted attacks and a "peeling back of the onion of Al Qaeda," says one intelligence expert.
At a makeshift laboratory in Kabul, there were smelly liquids and charred papers covered with chemical formulas; in Minnesota, a computer disk about crop dusting.
In caves outside Kandahar, Arabic-language exams were found that quiz terrorists-in-training on the best way to shoot down a plane or kill a man.
The paper trail alone is like a confetti shower in a Manhattan parade. But there have also been videos, artifacts and digital records most foul.
What they all amount to is still being sorted out. Some may not qualify as much more than terrorist curios.
But officials believe documents and a videotape found in Afghanistan and passed to authorities in Singapore foiled a planned terrorist attack and resulted in the breakup of an Al Qaeda cell there.
Such discoveries have exposed similar cells in other countries, officials said, without giving details.
Altogether, there's a lot to sort through.
An English-language book with instructions on how to survive a nuclear explosion was found at a compound in eastern Afghanistan where one of Usama bin Laden's wives lived. An issue of Chemical Weekly addressed to a public library in Kansas City, Mo., was discovered at an Al Qaeda camp.
During raids and arrests around the world, U.S.-led forces and law enforcement officers have collected gas masks, homemade videos — some famously starring Usama bin Laden — and American military reports on immunizing soldiers against anthrax.
On a board inside a house in Kabul, someone sketched a plane with the caption: "Your days are limited. Bang."
The materials have been shipped back to the Washington area for translation and sharing among the CIA, the Defense Intelligence Agency and the FBI, said Vince Cannistraro, a former CIA counterterrorism chief.
"They've found evidence in documents of culpability for specific terrorist operations that have taken place in the past," he said, declining to be more specific. "They have found names of people in terrorist cells abroad who are in place to conduct another operation."
All this has caused a "peeling back of the onion of Al Qaeda" in some parts of the world, he said.
Some of the items at Al Qaeda safe houses in Afghanistan were taken by journalists or thrown out by Northern Alliance troops before U.S. officials arrived. But the materials found have revealed new details about bin Laden's terrorist network — clues that could help prosecutors build cases against suspected terrorists, or help investigators interrogating Taliban and Al Qaeda members held captive by the United States.
An interrogation of a detainee might stall, said Defense Secretary Donald H. Rumsfeld, but information in a laptop or an address book in a house in Kabul might advance the case.
"You might arrest somebody with pocket litter that connects that person to one of the people you're interrogating," he said.
Bruce Yannette, who formerly directed the terrorism unit of the U.S. attorney's office in Washington, said the "scope of this operation is absolutely remarkable" considering what's been found so far.
"Hopefully, what these documents and these materials will do is help convince world opinion that what we're doing is appropriate and that this really was a murderous and criminal organization."
Documents relating to deadly chemicals and bacteria have been discovered inside houses abandoned by Al Qaeda after the Taliban fled Kabul on Nov. 13.
Material in Arabic, Urdu, Russian and English indicated the terrorist network was studying chemical, biological and even nuclear weapons — although it's unclear whether any such weapons were ever produced.
As U.S. troops wrapped up operations at the bombed-out Tora Bora complex near the border with Pakistan, they seized two Al Qaeda members, their computers, cell phones and training documents, officials said.
More often it was papers, not people that were left to be found.
"They were on the run," said former CIA terrorism analyst Stan Bedlington. "They had to travel light."
Sometimes what turns up is more of a personal nature.
Found at a makeshift laboratory in an Al Qaeda building in the heart of Kabul was a letter that a Pakistani named Mohammed Khaliq wrote to a brother in Peshawar, Pakistan, after the bombing began.
"Don't worry about me," he wrote. "Pray for me five times a day. Our enemy is not strong; we will win. If we die here, there is no greater reward."