The brothels mostly employ Latino women from the New York area, according to investigators. Court records indicate that virtually all charge the same rates -- $ 30 for 15 minutes of sexual intercourse -- and advertise using the same kind of business cards in Spanish. They also have the same operating procedures: Prostitutes punch playing cards or score sheets to tally each day's customers. "Every jurisdiction from Arlington to Montgomery County is seeing the same thing," said Alexandria police detective Harold Duquette, a member of the city's vice squad, which is investigating two of the alleged brothels.

Some of the brothels, which typically operate from the mid-morning to about midnight, also offer gambling and sell alcohol to attract customers, he said. Many are known as "social clubs" in the Latino community, Duquette said, although not all social clubs are brothels.

U.S. Immigration and Naturalization Service officials declined to be interviewed. But the agency issued a statement that said, "The INS ... has reason to believe that there may be prostitution rings operating here which may involve the transportation of female prostitutes to houses in the Metro Washington area from other states and the subsequent rotation of these women to other locations."

A New York Police Department spokesman said he was unaware of any network sending prostitutes to the Washington area.

Duquette said most of the brothels are set up in rented apartments and town houses in quiet, predominantly Latino neighborhoods. Then prostitutes are bused in from New York. After about a week, the women are rotated to other brothels or sent back to New York and are replaced by a new group.

While almost every jurisdiction around the Beltway has reported raiding Latino brothels, Arlington has had one of the biggest concentrations. Police there have raided more than a dozen such establishments since January 1993.

"It used to be typical for us to see more of the streetwalker or hotel prostitution where a customer is approached," said Arlington Detective Steve Broadhurst. "Now we're seeing escort services [and] bawdy houses in the Hispanic community."

Police say they don't know exactly how many of the brothels are in operation, but Broadhurst estimated at least 30 in the Washington area.

There are several theories on why the brothels have become so common. Community leaders say many Latino immigrants are men who came to the United States alone to work and send money back home to their families.

"Even if you've got a wife and kids that you're sending money to back home, you probably aren't going to be celibate," said John Liss, director of the Tenants' and Workers' Support Committee in Arlandria, a group with a predominantly Latino membership in the area bordering Alexandria and Arlington. "Sometimes the men turn to prostitution."

"There's a market out there and someone's taking advantage of it," said Hank Azais, a member of Prince William County's Hispanic Task Force. "People are concerned about what kind of effect it will have on the community. Prostitution is definitely not the kind of thing they want to see in their neighborhoods."

According to search warrants filed in Arlington Circuit Court and interviews with police officials in Virginia and Maryland, the prostitutes keep about half of the $ 30 fee, with the other half going to the man who watches the door and solicits customers.

Police have said that in many cases, the women work out of a bedroom that has been divided by partitions made of bed sheets. Each "room" contains a mattress, a garbage can and condoms, which police have seized by the thousands during raids.

In one Northern Virginia raid, investigators said they seized a kitchen timer intended to keep patrons from exceeding the 15-minute limit. Police said the raids also have turned up handguns, cash, record books and, in one Montgomery brothel, an empty cigarette pack stuffed with hundreds of small slips of paper advertising a good time.

Police also have seized business cards that advertise "Ropa Fina Para Caballeros," Spanish for "Fine Clothes for Men." Police say the ads are for the Latino brothels.

Prostitutes who have been arrested told police they had been working in New York when they were asked if they wanted to come to Washington and make "easy money," according to one investigator who has interviewed several of the women.

Many of the women, most of them undocumented immigrants from Central and South America, told police they were given bus tickets to the Washington area. Here, police said the women were set up in brothels run exclusively for Latinos, particularly Salvadoran men.

Prostitution is a misdemeanor in Virginia and Maryland, punishable by up to one year in prison.

Mark R. Voss, of Manassas, the court-appointed lawyer for a man who was charged with pandering after a recent raid on a Manassas brothel, said he is confident the establishments are part of a highly organized network.

"These women are being bused back and forth from New York like they're on a shuttle system," said Voss, who is on the Prince William Hispanic Task Force. "It has to be organized."

In the last three months, police have shut down two Hispanic brothels in Prince William. The most recent arrests, at the Irongate town house community just outside Manassas, came after complaints about the brothel from neighbors.

Established in apartment and town house complexes, the brothels are difficult to detect, police say, unless groups of men congregate outside. When police discover one, it is usually because a neighbor becomes suspicious.

Police say prostitutes have flourished in Arlington's Arna Valley and Arlington Forest communities, where two-story garden apartment buildings are easily accessible from the street, parking is ample and there is plenty of traffic.

One brothel identified in court records, in a two-story, red-brick building in the 4400 block of North Henderson Road, was across the street from Barrett Elementary School. Another house raided was just blocks away on the same quiet, tree-lined street.

Neighbors in Prince William's Irongate community said they became suspicious when men knocked on their doors at night looking for other addresses.

John Elliot's home sits directly behind the house that was raided at Irongate, a community of moderately priced colonial town houses.

On several occasions this summer, Elliot, 39, a correspondent for the Dutch radio and television network, said he saw men arrive by taxi at his neighbor's house.

"There were lots of intoxicated men who came in and out of the house," Elliot said. "I guess I just assumed there were five or six men living there."