A Pennsylvania father and son dispatched prostitutes to New York City, where livery cab drivers helped find customers for trysts that made the men big money but provided the women only a few dollars a night, prosecutors said Monday.

Six drivers were due to be arraigned Monday on promoting-prostitution charges in an unusually broad sex-trafficking case. It's expected to encompass charges against not only the alleged ringleaders and driver-recruiters but also, soon, some accused customers, according to the Manhattan district attorney's office.

The father and son, Vincent George Sr., 55, and Vincent George Jr., 33, both of Allentown, Pa., pleaded not guilty earlier this month to sex trafficking, money laundering and other charges. The men were being held without bail.

The son's lawyer, Richard Verchick, said it was too early in the case to comment. "There is not enough information to make a judgment," he said. The name of the father's lawyer wasn't immediately available Monday.

At a time when an unrelated case against an accused multimillion-dollar Manhattan madam has gotten extensive attention as a supposed example of an upscale brothel, the allegations in the case against the Georges draw a bleak counter-image.

"These women really are in an indentured situation," District Attorney Cyrus R. Vance Jr. said. "... Prostitution, I think more than people want to realize, involves men and women who are themselves in business, and kept there, because of coercion."

Soliciting business in hotel bars and outside strip clubs and through the cab drivers, the prostitutes made as much as $500,000 a year for men who threatened to beat them when they didn't bring in as much money as expected or were late to check in, according to prosecutors. The women commuted to Manhattan nightly to work, carrying cards that said they were "professional masseuses."

They were proprietarily tattooed with their pimps' nicknames — and in at least one case, a bar code — in a form of branding that's somewhat common, prosecutors said.

The Georges had multiple properties and a total of 10 cars, including a Mercedes apiece, prosecutors said. While the two provided housing and cars for the women, they got only enough cash from their $200 to $500 trysts to buy food and other necessities, Assistant District Attorney John Temple told a judge at the men's April 6 arraignment.

The livery car drivers got paid to drum up customers and negotiate prices, prosecutors said.

The father and son were on their way back home from recruiting a woman in Buffalo, N.Y., when they got phone calls about their homes being searched and discussed fleeing, prosecutors said. Pennsylvania state police arrested the two men, with the woman still in the car.

The case began as authorities noticed connections among some routine prostitution arrests, prosecutors said. Ultimately, the DA's office turned to wiretaps and follow-the-money techniques more often used in business-crime prosecutions to build a broader case charging sex trafficking — a fairly high-level felony that carries at least a year and up to 25 years in prison upon conviction. The New York Police Department and the federal Homeland Security Department also helped with an investigation that spanned state lines.

The wiretaps provided evidence that is expected to be used against some of the clients, prosecutors said.

"We are also taking on the demand side, to make the point that buying sex may involve victims of sex trafficking," said Vance, whose office launched a human trafficking unit in recent months.

Sex trafficking cases — which entail proving not only that prostitution took place but that it was coerced — can be difficult to pursue; some women don't see themselves as victims or are unwilling or unable to testify against their pimps. Vance's office has been focusing on using wiretaps or other means to build such cases without relying on alleged victims' testimony.

The office also has started keeping track of alleged prostitutes' tattoos, to look for patterns that could point to a sex trafficking ring, and debriefing customers in routine prostitution arrests to try to gather intelligence.

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