Federal agents arrested a 43-year-old Gaithersburg woman, her mother, two siblings and two men yesterday on charges of running a prostitution ring that operated out of several Montgomery County apartments.

They were charged with conspiring to transport illegal immigrants across state lines to engage in prostitution and of conspiring to harbor foreigners who were in the country unlawfully, according to a two-count indictment unsealed yesterday by a U.S. magistrate judge in Greenbelt.

Alleged ringleader Elsy Aparicio, her mother, Olinda Aparicio, 64, and Elsy's siblings Dorinalda Aparicio, 34, and Eliazor Gonzalez Aparicio, 29, operated brothels out of nine apartments in Montgomery County, six of them in Gaithersburg, prosecutors said. The other three were in Germantown, Wheaton and Hyattsville.

Manuel Jandres, 38, of Germantown and Jair Francis, 32, of Wheaton were also indicted. According to the indictment, one of Francis's tasks was to provide information to the Aparicio family about law enforcement inquiries into a brothel at the Georgian Woods Apartments in Wheaton.

Maryland U.S. Attorney Rod J. Rosenstein said the defendants transported many of the prostitutes from the New York metropolitan area, where most lived, to the Montgomery apartments.

Katherine Chon, co-executive director of the Polaris Project, an organization that monitors coerced prostitution in the Washington area, said a recent crackdown on brothels that operate as spas and massage parlors has shifted the trade to private residences.

"Obviously it makes it more difficult to detect when they're not in commercial establishments," Rosenstein said in an interview. "But this case demonstrates that we are capable of locating them wherever they are."

A law enforcement source close to the investigation said Elsy Aparicio first came to the attention of local police in 1996. Federal investigators began looking into the network roughly two years ago, said the source, who asked not to be identified because the case remains open. Most of the prostitutes were young Mexican women, but some were from Central America and a few were minors, the source said.

The owners advertised by word of mouth and by handing out business cards, the source said. They catered almost exclusively to Hispanic men, the source said. The source said the ring has operated out of at least 20 area establishments.

A similar criminal case filed this year against Elsy Aparicio's common-law husband sheds light into the alleged family business. Jonathan Lopez-Cruz, 31, the defendant in that case, admitted in court documents that he drove a white Chevrolet van with Maryland license plates to cities in New York and New Jersey to pick up women, who were then brought to Maryland to work at brothels.

FBI agents had learned that some women arrested on prostitution charges in Maryland lived in the New York area, Assistant U.S. Attorney Chan Park wrote in a court document filed in August. Newark FBI agents had seen women in the Maryland-bound van Dec. 3, 2004, and April 25 in Union City.

On May 9, New Jersey State Police troopers, working with FBI agents, stopped the white van at a gas station off Interstate 95 near Union City and found 11 women en route to Maryland brothels, according to the document.

Lopez-Cruz was driving, and agents identified a second male passenger as Manuel A. Romero, who authorities said had been arrested that year in Gaithersburg on prostitution charges. Lopez-Cruz had a notebook with the names, phone numbers and addresses of the women. Lopez-Cruz told agents that he charged each woman $50 for a one-way trip to Langley Park and that he sometimes drove the women back to the New York area.

The defendants will appear in federal court in Greenbelt today for detention hearings. A woman who answered the door at Lopez-Cruz's residence in Gaithersburg declined to comment yesterday. A second-story window at the red-brick house was shattered during the arrest.

Staff researcher Bobbye Pratt contributed to this report.