WASHINGTON –Since the Sept. 11 hijackings, an FBI lab here has been compiling a database of easily concealable knives – including long, fixed blades hidden in canes, retractable short blades hidden in keys and lipstick tubes, and others made of nonmetal composites that can escape detection by airport magnetometers and X-ray machines.

Most of the nearly 90 samples photographed in the extensive database of concealable weapons are commercially available for less than $20, the FBI says. [This .pdf FBI document contains a gallery of photos and takes about 1 minute to download.]

"These knives should be treated as potentially dangerous weapons," warns the "FBI Guide to Concealable Weapons 2003."

The booklet, put together by the Firearms and Toolmarks Unit of the FBI Laboratory Division at Quantico, Va., includes X-ray images of the knives to show how they might look if concealed in a carry-on bag and passed through a scanning device. Those made of plastic composites appear "invisible."

"It got a wide dissemination" in the federal government, FBI spokesman Ed Cogswell said of the booklet.

Transportation Security Administration spokesman Brian Turmail says he is not aware of the booklet, however, and could not say for certain if it has been distributed to all the federal security directors at the nation's major airports.

The hijackers who took control of commercial jetliners and crashed them into the World Trade Center and Pentagon were armed with box cutters.

The foreword to the FBI booklet says it is the "first installment of a continuing effort to collect and distribute information on knives that otherwise may be dismissed as nonthreatening items."

See photo gallery of FBI's most dangerous concealable weapons.

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