WASHINGTON — Counterterrorism tips have spiked in the days following the death of Osama bin Laden as a result of a more alert, or perhaps more anxious, American public, law enforcement officials say.
Many of these clues are being entered into databases across the country and pored over by counterterrorism experts. Depending on the state or city, the data may be retained for years.
While law enforcement officials say the information helps them to connect the dots to prevent the next attack, the avid gathering of data raises concerns that police are collecting personal information about Americans who aren't criminals.
The collection effort also comes as domestic spying continues to grow, according to a recent report by the Justice Department.
"It's been a huge boon to the national counterterrorism effort," said Clark Ervin, the former inspector general of the Department of Homeland Security. "Our officials can't handle the huge volume of information that comes in, so they've got to depend on the public to be their eyes and ears."
But Ervin, who now heads a homeland security program at the Aspen Institute, acknowledged that "one person's version of what is suspicious is another person's normal behavior."
"It can obviously be misused," he said.
Most law enforcement officials don't see any reason for controversy.
"It's what cops have been doing for more than 100 years," said Thomas J. O'Reilly, a former New Jersey state police official who heads the Justice Department's Nationwide Suspicious Activity Reporting Initiative. "And I think it's what the citizens expect. If they see something suspicious, they want the police to check it out."
Since the Sept. 11, 2001, terrorist attacks, law enforcement officials have identified about 16 potential terrorist behaviors, such as taking photos of "high-value" targets. The tips, known as "suspicious activity" reports, are vetted by counterterrorism experts who are trained to know the difference between "tourism and terrorism" behavior, officials said.
For example, taking a photo of a bridge is legal.
"However, taking photos of a bridge and its security features, documenting security routes and the number of security personnel at the bridge at different times of the day may be interpreted as suspicious activity," said Mike Dayton, acting secretary of California's emergency management agency.
They also are trained to look for these behaviors rather than focus on someone's race or ethnicity, officials said.
On average, only about a third of the tips in databases include someone's name, officials said.
"We're more interested in the trends," Dayton said.
But Michael German, a former FBI agent who now advises the American Civil Liberties Union, said the program gives officers such wide discretion that innocent people are being questioned and even arrested based on legal behavior.
In 2009, a libertarian activist was arrested after videotaping a protester outside the federal courthouse in Manhattan.
Federal officers forced the activist to the pavement and confiscated video from his camera, according to the ACLU. The software developer for an investment bank filed suit against the federal government and forced officials to acknowledge that he did nothing illegal. German said it's unclear whether the incident was entered into a database as a "suspicious activity."
"The scenario that we're concerned about is a police officer sees someone they don't like, and now they have this program that allows them to go and harass this person if they have a camera ," he said. "They can demand an ID, arrest them and put a name in the database."
After Sept. 11, police and sheriff's departments across the country began transforming databases set up for transit systems or local law enforcement into collection points, or fusion centers, for counterterrorism information.
The federal government boosted funding for the fusion centers so the data could be analyzed by experts.
In the latest push, 30 states have agreed to share their analysis and about 10,000 suspicious activity reports in a federally endorsed system.