(09-22) 15:00 PDT WASHINGTON, (AP) -- A quart-sized container of homemade explosives is cheap, deadly and difficult to detect — and that is exactly why the type of chemical bomb feared to be at the heart of an ongoing terror investigation worries law enforcement so much.
As FBI and New York police counterterrorism agents investigate a Denver man who authorities say received al-Qaida explosives training and recently traveled to New York, law enforcement officials around the nation have been advised to be on the lookout for any signs of bombs built with hydrogen peroxide.
That type of weapon killed 52 people in the London transit system four years ago. During the morning rush hour of July 7, 2005, three men carried backpacks that exploded within 50 seconds of each other on three London Underground trains. A fourth bomb exploded on a bus nearly an hour later.
The same chemical components were allegedly at the heart of a failed plot to blow up commercial passenger jets leaving England for America. That plot was based, according to court evidence, on amounts of chemicals small enough to fit into soda or water bottles.
Now, according to law enforcement officials speaking on condition of anonymity because they were not authorized to discuss the investigation, authorities are concerned that 24-year-old Afghan immigrant Najibullah Zazi may have been trying to put together a plot to detonate similar devices in backpacks, possibly on crowded commuter trains in New York. Zazi has been charged only with lying to authorities, and has told reporters he has nothing to do with terrorism.
Dan Watts, a research professor at the New Jersey Institute of Technology, said a bomb made from hydrogen peroxide is very different from the kind of truck bomb explosion used in the 1995 attack on the federal building in Oklahoma City.
"With a hydrogen peroxide-based explosion, you won't get that kind of damage. They're more effective in a more confined space. When you hear about them being particularly horrific, it's a railroad car, a situation like London, rather than trying to bring down a big building," said Watts.
When mixed together to make a bomb, the material is so unstable, it can be triggered accidentally by heat or shock.
In a laboratory setting, a quart of the material exploding can destroy the entire lab, said Watts.
"They don't blow the walls down, but everything in the lab can be ruined," he said.
Shortly after federal agents looking for explosives raided several Queens apartments linked to Zazi, officials in Washington issued a bulletin to police around the nation specifically citing the case and urging them to be on the lookout for any signs of people building peroxide-based bombs.
Such signs include burn marks on people who have handled the bomb components, apartments using large fans or big refrigeration units, and purchases of large amounts of certain household chemicals to make the bombs.
That Sept. 14 bulletin also reminded police that recipes for building bombs are taught in terrorist training camps and in widely circulated terror manuals.
"Hydrogen-peroxide based explosives are powerful and highly unstable; furthermore, similarities in appearance and methods of production can cause first responders to mistake certain explosives for chemicals used to manufacture narcotics," the bulletin says, reminding officers of the London attacks and telling them such bombs can be carried in "a backpack, suitcase plastic container, or other hand-carried item."