BOSTON — A security camera recorded the man wearing dark sunglasses and a hooded sweat shirt as he walked by Boston's Symphony Hall on Feb. 9 and dropped a cardboard tube marked "Anthrax Beware" at the door.
Emergency medical crews raced to the site, firefighters cordoned off the area, police halted traffic, and life came to an anxious halt until a hazmat team signaled the all-clear: The tube was empty.
In the 7 1/2 years since America's worst bioterrorist attack -- when letters laced with anthrax spores killed five people, closed Congress and the Supreme Court, and crippled mail service for months -- U.S. agencies have spent more than $50 billion to beef up biological defenses.
No other anthrax attacks have occurred.
But a flood of anthrax hoaxes and false alarms have raised the cost considerably through lost work, emergency evacuations, decontamination efforts, first-responders' time and the emotional distress of the victims.
That, experts say, is often the hoaxer's goal.
"It's easy, it's cheap, and very few perpetrators get caught," said Leonard Cole, a political scientist at Rutgers University in Newark, N.J., who studies bioterrorism. "People do it for a sense of power."
Among the recent targets: nearly all 50 governors' offices; about 100 U.S. embassies abroad; 52 banks; 36 news organizations; ticket booths at Disneyland; Mormon temples in Salt Lake City and Los Angeles; town halls in Batavia, Ohio, and Ellenville, N.Y.; a funeral home and day-care center in Ocala, Fla.; a sheriff's office in Eagle, Colo.; and homes in Ely River, N.M.
The FBI has investigated about 1,000 such "white powder events" as possible terrorist threats since the start of 2007, spokesman Richard Kolko said. The bureau responds if a letter contains a written threat or is mailed to a federal official.
"Some of these knuckleheads think because they're not sending a dangerous substance, it's not a crime," Kolko said. "But it is a crime. We don't treat a hoax as a joke."
In one recent case, emergency crews cleared and sealed a Department of Homeland Security office in Washington after a senior official, who had received a package at home containing white powder and a dead fish, brought it to work for inspection.
The contents proved harmless, and the official, who collects intelligence on weapons of mass destruction, remains a department employee, a spokeswoman said.
Other cases, however, are more worrisome.
