The documents, obtained by The Associated Press under the Freedom of Information Act, also detail how the FBI scurried last year to prove it wasn't "randomly looking at everyone's e-mail" once its Web surveillance practices came under attack.
The FBI records show the agency used its controversial Carnivore system 13 times between October 1999 and August 2000 to monitor Internet communications, and a similar device, Etherpeek, another 11 times.
Essentially, Carnivore is like a wiretap on the Web. Physically it's nothing more than a small computer the FBI can lock inside the switching room of an Internet service provider, say, America Online. But instead of reading every AOL customer's e-mail, it is designed to zero in and record just the messages sent to and from one particular e-mail address.
Etherpeek is a commercially available network monitoring program that is far less precise in filtering the information collected.
But critics point out that wiretapping the Internet is different from wiretapping a telephone.
If the FBI wants to tap your phone, it gets a court order and the phone company makes the appropriate connection for investigators.
If the FBI wants to bug your Internet address, it gets a court order and then its own agents can install the tap themselves.
"Carnivore has access to much more information than it is legally entitled to collect," the Center for Democracy and Technology's Alan Davidson testified before Congress last year. "How do we know that we can trust Carnivore? How do we know what kind of leash has been put on Carnivore?"
Some Internet service providers have raised concerns that since Carnivore's inner workings are secret, it may damage or slow down their networks while it's capturing e-mails.
While large portions of the FBI documents are blacked out to protect national security and investigative secrets, they reveal new details about the agency's Internet surveillance program.
In January 2000, for example, FBI agents got a wide-ranging order to use a computer wiretap in a gambling and money laundering investigation. The wiretap was successful, according to an e-mail to Marcus Thomas, head of the FBI's cybertechnology lab.
"We got bank accounts, where money was hidden and other information," reads the e-mail from an unknown agent. "Some of the data sent ... was instrumental in tying several of the conspirators to the crime. One of the conspirators is offering to pay ... as part of a plea bargain."
The following month FBI investigators used Carnivore to catch a fugitive for the U.S. Marshals Service. The Internet provider involved protested in court, but was ordered to cooperate.
The 24 instances of Internet surveillance also included four investigations of computer hacking, tree drug probes, one extortion investigation and an intellectual property case. The nature of the other cases was not disclosed. The FBI has said that Carnivore has been used in investigations involving national security and attempted domestic terrorism.
E-mails between FBI agents show how determined the bureau was to justify Carnivore's existence after the disclosure of it last year raised protests from lawmakers and privacy advocates.
In July, the Tampa, Fla., field office sent an e-mail to other agents, including Thomas at the FBI lab, offering a slide show explaining how a militia group used the Internet to communicate.
The group's leader pleaded guilty and was sentenced last year for planning to break into military facilities to steal explosives and blow up energy facilities in southeastern states.
"This might be used to show why Carnivore is necessary and essential for law enforcement to combat terrorism," reads the e-mail from an unspecified Tampa agent.
Thomas replied: "This kind of information would be very helpful in fighting the idea that we are randomly looking at everyone's e-mail."
The FBI 2002 budget request includes more than $13 million for Internet surveillance, $2.5 million more than this year. Most of the new money would go for research and development.
In justifying the budget, the FBI cybertechnology lab said the number of requests for Internet wiretaps from FBI field offices increased by 1,850 percent from 1997 to 1999. The exact number of requests was not disclosed.
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