SARATOGA — On the border of this leafy Silicon Valley suburb of million-dollar homes, chic salons and eateries, one of at least four Spanish human-trafficking victims slept in a coffin-size room with the lights on all night — to keep the roaches at bay.

Another was forbidden to leave the Saratoga beauty salon where she toiled for what authorities say was almost nothing, even though that meant going without food for as long as nine hours. Yet another got blisters on his feet from putting in 60-hour weeks without pay at a tapas restaurant where the owners rake in $35 for a plate of gourmet ham.

Santa Clara County prosecutors Friday charged their alleged oppressors — a 44-year-old woman and the two men she lived with — with three felony counts of human trafficking and one count of wage theft in a rare criminal case involving allegations of labor exploitation. Although trafficking in human labor is much more common worldwide than sex trafficking, it rarely surfaces — particularly in affluent communities like Saratoga and west San Jose.

“People think human trafficking only happens on the east side at shoddy restaurants or sweatshops,” prosecutor Paola Estanislao said. “This case is a good reminder it can happen anywhere.”

Suspects Esther Narbona-Sanchez, 44; Paulino O’Farrill, 47; and Pedro Barea-Riva, 44, were arrested Tuesday at their ranch home near Westgate mall in San Jose and held without bail. Since then, their Saratoga businesses, including their restaurant TapaOle in Saratoga’s Quito Village Shopping Center on Cox Avenue and the Utopik Salon on Saratoga-Sunnyvale Road, have remained shuttered. If they are convicted, they would face a range of possible punishments, from probation to more than 10 years in prison.

So far, the victims include three women and one man who range in age from 21 to 38. But the investigation is continuing by a human trafficking task force made up of the prosecutor, an investigator from the District Attorney’s Office, three sheriff’s deputies and an FBI agent. The prosecutor said Friday there are at least 15 more potential victims.

The group recruited workers from Spain, she said, starting about four years ago, and put them up in two sheds, as well as a tiny anteroom at the back of their house with cracks in the wall where cockroaches would scuttle through. In one case, an associate in Spain recruited a hair stylist, but the rest appear to have been hired through a popular Spanish website called “milanuncios,” which runs classified ads.

According to a law enforcement source, the suspects are a threesome in an open relationship. The criminal charges, as well as the nature of their relationship, shocked neighbors who live on Duvall Drive. There were few signs that workers were being housed in substandard conditions behind the beige house with burgundy shutters and a fenced-in yard.

Narbona-Sanchez was often seen with her 2-year-old twin sons, who are now in the care of Child Protective Services.

“Oh my God, this is so sad,” said Yukari Shaw, a bookkeeper who lives nearby. “I read about nail salons, but I didn’t realize it could happen right across the street.”

In retrospect, neighbor Joe Sanchez said, things changed at the house, where he once took care of cats while Narbona-Sanchez and Barea-Riva were in Europe.

“At first it was just the two of them,” he said. “Then there were a bunch a people coming in and out the side gates.”

Desperate to make a living after the global economic collapse in 2008 hit Spain particularly hard, at least three victims accepted the jobs without meeting the restaurant and salon owners, Estanislao said. In some cases, the group paid for their tickets and told them they could work off the debt.

“They promised the women they could make $3,000 to $5,000 a month, and live rent-free at their house,” she said, adding that one victim also brought her boyfriend, who worked in the kitchen at TapeOle. “They were very trusting. They are people from their country. They are coming from an area where there is no work.”

But then at some point, the group would demand $500 in rent, the prosecutor said. Their pay would either be docked for the airfare and rent, or they wouldn’t be paid at all, she said.

“I call it debt bondage,” Estanislao said.

The victims didn’t speak English and were unfamiliar with American laws. So it was easy for the suspects to cow them into submission, she said — at least for a little while.

“They’d say, ‘If you see cops come by the salon, put down the blinds,'” Estanislao said. “‘If the cops come in and ask for your beautician’s license, just say you are an assistant.'”

One victim put up with it for about four months; the others only for a month or two. At least one of them reported the situation to police, prompting the task force’s ongoing investigation. The victims were then put in touch with the South Bay Coalition to End Human Trafficking, a consortium of nonprofits that offer counseling, housing and immigration advice.

Narbona-Sanchez is set to be arraigned Monday. The two male defendants, O’Farrill and Barea-Riva, were arraigned Friday. Superior Court Judge Shelyna V. Brown set bail for all three at $900,000 apiece.

The Board of Supervisors has spent about $1 million to fund the task force, which Supervisor Cindy Chavez commended for catching the group. The Bay Area is considered a magnet for human trafficking, partly because of the diversity of the population, which allows the problem to be “hidden in plain sight,” as activists often say while urging the public to report their suspicions.

“The scourge of human trafficking,” Chavez said, “is still prevalent throughout our county.”

Anyone with information about the Saratoga case or other cases in Santa Clara County can call the task force at 408-918-4960. To report human trafficking elsewhere, call 888-373-7888. If you are a victim, you can text 233733 and put “help” in the message.

Contact Tracey Kaplan at 408-278-3482. Follow her at Twitter.com @tkaplanreport.