NEW YORK - Susan Liu canvasses the streets in front of massage parlors in New York City once a month. Her goal: to befriend the women who work there, many of whom she believes are being sex-trafficked.
Liu is the director of women's services at Garden of Hope, an organization that provides trafficked women in massage parlors with counseling and access to lawyers.
"Many people do not know the background of these women, who are so brave to come over the ocean to a new place to find ways to support their families," she said. "It's about looking for a better life, just like any immigrant or any citizen in any country."
Liu is part of a growing number of advocates finding innovative ways to overcome cultural and language barriers to help trafficked women forced to sell sex in more than 9,000 massage parlors across the United States.
The anti-slavery group Polaris estimates that traffickers make $2.5 billion a year from the trade, which mainly involves women from China and Korea working behind storefronts along highways and in strip malls, and living in fear of deportation.
After escort services, it is the second most common type of trafficking reported to the charity's national hotline, which received almost 14,000 calls last year.
Many of the women are illegal immigrants who are recruited by traffickers promising legitimate jobs and later asked to perform sex acts, campaigners say.
They speak little or no English and often face pressure to repay debts and support their families, according to advocates, who said it is hard to help the women because they are kept quiet with threats and moved among locations every few weeks.
"The response to American-born pimp-controlled victims isn't going to be the same as foreign-born victims who don't just have different vulnerabilities, but also different cultural backgrounds," said Rochelle Keyhan, a director at Polaris.
As discussing sex is taboo in China and domestic violence is not taken seriously, victims are more likely to talk about labor exploitation than reveal sexual abuse, she said.
Websites like Rubmaps.com, where men review massage parlors that offer sexual services, are helping to fuel the crime, but identifying traffickers and their victims is difficult, police and campaigners say.
Globally, human trafficking earns profits of roughly $150 billion a year for traffickers, according to the International Labor Organization. That figure includes profits from sexual exploitation and forced labor.
Trafficked women in massage parlors are often assaulted by their customers but they feel helpless because they fear the police and cannot speak English, advocates say.
"What we were hearing from those women is when they said 'no,' the customers would beat them up, they would rape them, they would try to strangle some of our clients," said Lori Cohen, a director of Sanctuary for Families, a support group.
One survivor recalled finding a massage parlor job online, and being told that she would not have to offer "full service" — meaning intercourse — or other sexual services.
"When I started working, I was asked to compensate for the fees lost if I refused to provide 'full service' to the customer," the woman, who declined to give her name, told the Thomson Reuters Foundation.
"I have been beaten up by customers. ... I had also been threatened by a customer with a knife before when I refused to provide 'full service.' "
Still, she said that she was afraid of losing the job because she did not have a work permit, needed to repay the agent who applied for her tourist visa, and needed to support her son.
Women's immigration status often deters them from reporting their traffickers to the police, said Cohen.
"There's a tremendous amount of fear in the immigrant community that if a victim tries to seek help, she will be arrested and deported," she said.
Police have charged workers with prostitution in an effort to target the trade, which makes them distrust the force.
"What we've heard from many of our clients is that they feel like they're being blamed," said Mary Caparas of Womankind, which works with trafficking survivors.
Activists are trying to build confidence by bringing the police into massage parlors.
New York police have visited massage parlors with Mandarin-speaking staffers from groups like Garden of Hope and Sanctuary for Families to encourage victims to come forward.
"We have to gain the trust of a population that doesn't necessarily trust law enforcement," said inspector Jim Klein.
Victims often hesitate to get their traffickers in trouble as they look to them for guidance, so building new support networks is vital, said Liu.
Counselors at Garden of Hope use texts, calls and WeChat — a popular messaging app in China — to stay in touch with survivors and women working in massage parlors.
They encourage the women to let them know if they have run into trouble with their traffickers or immigration authorities.
Survivors also volunteer as counselors at the organization.
"This feels like, 'I'm coming home to my family,' " said Liu. "A lot of times, they will call their counselors 'my jie jie,' " meaning sister.