NEW YORK - Since the Sept. 11, 2001 attacks, an untold number of hoaxers have preyed on fears of terrorism on U.S. soil with schemes designed to win favors from the government, settle personal scores or simply cause mischief, authorities say.
A tip last year from would-be FBI informant Tanveer Choudhry sounded frightening. The Pakistani immigrant told agents two "brothers" planned to hijack a pair of gasoline trucks and turn New York's Verrazano Narrows Bridge into an inferno that would "kill Jews." Before New Yorkers knew anything about it, investigators came to a familiar conclusion: He was lying.
Most of the terror threats have been quickly and quietly discounted. But an alleged al-Qaida plot to bomb the New York subway system highlighted the potential for possible threats to spread fear and tie up investigators before they prove to be false alarms.
"Hoaxes waste resources that are needed to chase down real tips," said Dean Boyd, spokesman for U.S. Immigration and Customs Enforcement, the investigative arm of the Department of Homeland Security.
Choudhry was deported after admitting he lied about the bridge plot in a bid to win asylum - a common motive. Other tipsters make false accusations "to get back at their ex-wives or someone they were in car accident with. ... You name it," Boyd said.
Hoping to discourage phony threats, Congress passed a law last year making it a crime for anyone to convey false or misleading information about a terrorist attack or possible terrorist attack. If convicted, a defendant can get up to five years in prison; if the hoax causes injury or death, the maximum term would be 20 years to life.
The recent subway threat apparently was more a case of bad information than pure fabrication.
Based on a tip by a paid informant in Baghdad, city officials and the FBI last week issued a public warning. Thousands of police officers were deployed, turning the subway into an underground armed camp.
Four days later, the protection was lifted after investigators found no evidence to support his story that a team of terrorists would use briefcases and baby strollers packed with explosives to attack the subway system.
Despite scattered news reports that the threat was a hoax, some federal officials have said it's more likely the informant was passing along false information he believed was true.
Local officials also have steadfastly stood by their decision to boost security, saying the informant had passed a lie detector test and had a good track record, and that his warning was too detailed and dire to be ignored.
"This was a planned attack that had a specific time and target and method," Mayor Michael Bloomberg said this week after the threat unraveled. "It was the first really serious allegation of a direct attack on this city since 9/11."
Less serious threats - some chilling, yet bogus - usually have come and gone without becoming full-blown scares.
Last December in upstate New York, Danian Terzi alarmed the state troopers who arrested him for purse snatching by claiming he and other conspirators had smuggled C-4 explosives from St. Louis to New York with intentions of detonating a bomb in Times Square on New Year's Eve.
Court papers say that after the FBI was called in, Terzi "recanted the story and admitted the story was an elaborate hoax."
In another case last year, Ahmed Allali - an Algerian immigrant and Indianapolis gas station owner facing deportation for having a fraudulent passport - claimed he had traveled to the United States in 1998 with al-Qaida operatives, and provided extensive details about a sleeper cell that was planning to set off bombs in five major cities. The scare tied up scores of investigators before Allali admitted making up the tale to avoid being kicked out of the country.
Earlier this year, a suspected immigrant smuggler in Mexico sent investigators scrambling again when he called in a threat alleging that a pair of Iraqis had crossed the border and were plotting to strike Boston with a dirty bomb.