When criminals operate online through a Wi-Fi network, law enforcement agents can track their activity to the numeric Internet Protocol address corresponding to that connection. But from there the trail may go cold, in the case of a public network, or lead to an innocent, if careless, owner of a wireless home network.
"We had this whole network set up to identify these guys, but the one thing we had to take into consideration was Wi-Fi," Gilhooly said. "If I get to an Internet address and I send a subpoena to the Internet provider and it gets me a name and physical address, how do I know that that person isn't actually bouncing in from next door?"
Gilhooly said the possibility of crashing into an innocent person's home forced his team to spend additional time conducting in-person surveillance before making arrests. Gilhooly said the suspects tracked for Operation Firewall would regularly advise one another on the best ways to gain access to unsecured Wi-Fi systems.
"We intercepted their private conversations and they would talk and brag about, `Oh yeah, I just got a new amplifier and a new antenna and I can reach a quarter of a mile,'" he said. "Hotels are wide open. Universities, wide open."
Sometimes, suspected criminals using Wi-Fi do not get out of their cars. At 5am one day in November 2003, the police in Toronto spotted a wrong-way driver "with a laptop on the passenger seat showing a child pornography movie that he had downloaded using the wireless connection in a nearby house," said Detective Sergeant Paul Gillespie, the officer in charge of the child exploitation section of the sex crimes unit for the Toronto police service.
The suspect was charged with child pornography violations in addition to theft of telecommunications services; the case is pending.
"The No. 1 challenge is that people are committing all sorts of criminal activity over the Internet using wireless, and it could trace back to somebody else," Gillespie said.
Holly Hubert, the supervisory special agent in charge of the Cyber Task Force at the FBI field office in Buffalo, New York, said the use of Wi-Fi was making it much more difficult to track down online criminals.
"This happens all the time, and it's definitely a challenge for us," she said. "We'll track something to a particular Internet Protocol address and it could be an unsuspecting business or home network that's been invaded. Oftentimes these are a dead end for us."
Hubert says one group of hackers she has been tracking has regularly frequented a local chain of Wi-Fi-equipped tea and coffee shops to help cover its tracks.
Many times the suspects can find a choice of unsecured wireless networks right from home. Special agent Bob Breeden, supervisor of the computer crime division for the Florida Department of Law Enforcement, said a fraud investigation led in December to the arrest of a Tallahassee man who had used two Wi-Fi networks set up by residents in his apartment complex.