WASHINGTON, D.C. – Somewhere among the thousands of calls and tips to police from citizens, amateur detectives and plain old kooks may be the one tip that trips up the sniper stalking the Washington area and helps police nab him.
Public tips have historically helped police tremendously when they have little physical evidence to help solve the deadly shooting spree. Citizen help has led to capture of some of the nation's most wanted criminals, from Depression era-gangster John Dillinger to Unabomber Ted Kaczynski.
"The right tip is worth 100 detectives," said San Francisco State University criminology professor Mike Rustigan.
But how do police comb through the flurry of tips coming in after more than a week of daily pleas for help in the sniper case?
Especially since "most tips are worthless," said James Alan Fox, a Northeastern University professor who studies serial killers. "It becomes a tremendously difficult task of separating."
But computers can lend a helping hand.
The FBI's "Rapid Start Team" is using special software to log all tips, farm out the strongest leads to investigators and track the results of their investigations. The product is a searchable database from which all tips that mention "white van," for example, can be quickly retrieved.
The FBI has used the system for more than a decade for big crimes around the world, including the Oklahoma City bombing and the attack on the USS Cole, agency spokesman Bill Carter said.
A national, toll-free hot line set up by the FBI (1-888-324-9800) was overwhelmed by calls, sometimes as many as 1,000 an hour Friday. Even with 47 lines to that number, some callers got busy signals.
Authorities urged people to keep calling, even if their information seems insignificant.
"Let us decide whether what you saw, what you heard, has something to do with the investigation," said Montgomery County, Md., Police Chief Charles Moose, whose department leads the investigation. He assured would-be tipsters they could remain anonymous.
From the more than 7,000 calls since the shootings began Oct. 2, Montgomery County police said they had checked out at least 1,700 "credible leads."
Criminologists say high-profile investigations always are swamped by callers, some offering solid leads, others giving advice or proffering wild theories. Police must try to quickly prioritize the information.
For instance, a caller who heard a neighbor brag about killing gets precedence over someone reporting gossip about a neighbor. Specific, detailed information -- such as a description of a person or vehicle seen near a shooting site -- gets immediate attention.
"They tell the public 'we will investigate every tip,' but they can't," Rustigan said. "You can dismiss a lot of the vague stuff right away."
Moose offered an example: "Some leads suggest we go to all the gun shops on the East Coast. That is not a credible lead."
Past cases show breakthrough tips sometimes come from criminals' family members. It was Kaczynski's brother who alerted police. Ex-spouses and jilted lovers often tattle. Dillinger was turned in by a madam who spotted him in her brothel.
Sometimes good tips are bungled. FBI spy Robert Hanssen's brother-in-law, also an FBI agent, passed along his suspicion that Hanssen was selling secrets to Moscow as early as 1990. But it took another 10 years -- marked by tips from another double agent and even from the Russians themselves -- before the FBI uncovered one of America's most-damaging turncoats.
Keeping watch for wrongdoers has blossomed into an American pastime. There are real-life crime programs, such as "America's Most Wanted;" Internet sites that list fugitives and encourage tipsters; missing children on milk cartons; and, most recently, the government's call for all Americans to help guard against terrorism.
"We now have grown into a society where we suspect our neighbors of everything," said Tod W. Burke, associate professor of criminal justice at Radford University in Virginia. "We've grown more observant. In a case like this, that's not so bad."
To encourage the public to help, a reward of $500,000, built partly from individual contributions, was offered for information leading to indictment of a suspect or suspects.
Montgomery County spokeswoman Donna Bigler says employees stopped keeping a running tally of the Montgomery County Reward Fund because of the pace of contributions.
Separate funds are assisting or honoring several of the sniper's victims.
Sonny's Kids, in memory of James "Sonny" Buchanan, will benefit needy youths in the community.
The Sarah Ramos Memorial Fund will support Ramos's husband and young son.
Another fund will help the husband and young daughter of Lori Lewis Rivera.
The Benjamin Tasker October 7th Fund will assist the 13-year-old student critically wounded outside that school.
The Associated Press contributed to this report.