St. Louis- Everybody knows that cops use high technology to track bad guys. But vice officers here were startled to find bad girls using high tech to track cops.

In the cat-and-mouse game of fighting prostitution, the cats and mice alike have turned to computers.

St. Louis County police recently discovered a Web site on which a network of prostitutes had gathered and shared information about undercover officers – mainly theirs.

Rick Battelle, commander of the county vice squad, discovered that even his own cell phone number was listed. “That was the shocking thing,” Battelle said. He had used it only once to book a “date” with a suspected hooker.

Traditionally, police have kept computerized databases on prostitutes: their movements, fictitious names and hide-outs. Prostitutes have increasingly advertised over the Internet, often under a thin guise of escort services.

What detectives found recently was a melding of the two: a database shared on the Internet to help working girls help each other stay out of trouble.

It was revealed by chance.

Police had been working for months to get close to two women from Springfield, Mo. Like many others, the pair had used message boards, e-mails and Web sites to promote their business and to screen clients. They extended their reach by booking customers in several cities, including the St. Louis area.

“You will still always have the seedy end of prostitution with women on the street trying to feed their crack habit,” said county police Capt. Thomas Jackson. “But you also will have others who see it as a business. It’s only natural that these people on the high end are going to use technology.”

A check for “St. Louis escort services” on a typical Internet search engine, like Yahoo.com, yields more than 100 listings offering pictures and profiles of women and men. A customer can sign up for an e-mail announcing when a favored prostitute is coming to town, police said.

Internet escorts charge more than typical streetwalkers do – up to $500 for an encounter, according to investigators.

The two from Springfield were wary targets, police said, and getting an appointment was difficult. Officers finally set up a rendezvous and moved carefully. They drove unmarked cars and used fake names. They said they employed secret tactics designed to trick even the most paranoid prey.

Finally, on Aug. 4, an undercover officer met the women at a hotel in Maryland Heights. Once the prostitutes accepted money for a promise of sex, other officers, who were listening in, raided the room.

Investigators found two laptop computers, which they said was common for escorts who work the Internet. But on a Web site on at least one of the computers, the police found something quite uncommon. It was a listing of their own cell phone numbers, undercover names, makes and models of their cars and even license plate numbers.

Prostitutes had paid careful attention to details, for example listing a cell phone number if it had been used to make an appointment that turned into an arrest.

Only a hooker with a secure log-in could get access to the Web page, police were told, and only someone with several hookers to vouch for her could get the log-in.

The two suspects were arrested and released pending filing of charges. County police are checking whether the Web site can be construed as racketeering under federal law, since it was intended to further a criminal enterprise. Nobody has been arrested or charged in connection with it so far, and the Web site may still be operating.

Although many of their tools and techniques were compromised, county police noted, they still managed to arrest the women from Springfield.

“We have to find ways to adapt because they are,” Battelle said.

While resourceful, police said, the Web site won’t necessarily be very effective – especially now that vice cops are onto it.

“Once information about an identity or a vehicle is out there, it’s not all that difficult for us to change it,” Jackson explained. “Information about our officers is useful to prostitutes only when it’s fresh. It doesn’t stay fresh for long.”