"A lot of them are very scared to go out of their home, if it's not work or to take their kids to school, because of immigration."

By Ellen Wulfhorst

ALAMO, Texas, June 11 (Thomson Reuters Foundation) - Fear of tightened border patrols and tough new immigration laws is driving victims of human trafficking into hiding in the Rio Grande Valley at the southern tip of the U.S. border with Mexico, according to a Thomson Reuters Foundation investigation.

FACTBOX-Tighter security, immigration crackdown boost trafficking concerns along U.S.-Mexico border

Stretching more than 100 miles (160 km) along the river that divides the two nations, the Valley in Texas has long been a major entry point for Central American migrants who stay and find jobs as farmworkers, ranchhands and housekeepers.

But worried and silenced by the nation's hardened attitude toward migrants, frightened workers face greater risk of falling victim to forced labor, trafficking, wage theft and debt bondage, advocates and officials told the Thomson Reuters Foundation during several trips over a five-month period.

The number of calls from trafficking victims to the National Human Trafficking Hotline fell 30 percent to 325 last year in Texas, listed by the U.S. government as having the most human trafficking activity alongside New York and California.

"The fact is they hide, even from us," said Jose Torres, a grizzled legal aid investigator who has roamed the fields of the Valley helping trafficked farmworkers for four decades.

Already reluctant to reveal their plight, casualties of trafficking are even more distressed by "the Trump situation," he said.

President Donald Trump wants to build a border wall with Mexico - promoted in part to stop drug smuggling and criminal immigration - and his administration plans to expel 250,000 immigrants from Honduras and El Salvador.

In the Valley, National Guard helicopters fly low overhead and Customs and Border Patrol agents keep watch on city streets and remote dirt roads.

Added to that, Texas has a new state law called SB4 that allows law enforcement to ask for a person's immigration status.

The stepped-up policing and laws like SB4 create a "chilling effect," said Efren Olivares, racial and economic justice director at the Texas Civil Rights Project.

"We are already seeing that happening," he said. "We are very concerned it's going to affect and revictimize human trafficking victims."

More than nine in 10 people have Hispanic roots in the fast-growing Valley, and traffic clogs the imposing port-of-entry bridges spanning the Rio Grande from Mexico.

Signs in Spanish hawk Mexican fare at cantinas and taquerias, where stray dogs hunt for scraps.

Migrant fieldhands ride in pick-up trucks to gather oranges, cauliflower and onions, and domestic workers wait at bus stops to start their days cooking and cleaning.

Throughout the Valley, workers without legal immigration documents fear being found out and deported. Those with legal papers do not want to jeopardize family members who do not.

Yolanda, a Mexican domestic worker in the country illegally for more than a decade after overstaying a visitor visa, told the Thomson Reuters Foundation that her employers don't always pay her wages after she cleans their houses.

"They'd say, 'Yeah I'll pay you. Yeah, I'll pay you,' but then they never paid," said Yolanda, who did not want to give her surname. "There are many bad people, people who are like that."

Her husband Luis added: "There's nothing you can do about it. With this president, everything is very difficult."

CAPTIVE AND HELPLESS

Although few victims speak up, the state is home to an estimated 234,000 adult labor trafficking victims, according to 2016 research by the University of Texas. Their captors earn as estimated $600 million a year in illicit profits.

The U.S. Department of Health and Human Services estimates a quarter of the 50,000 or so people trafficked every year from foreign countries to the United States enter through Texas.

"The number that we're serving is very small, compared to the actual numbers that are at risk or could be victims of trafficking," said Rachel Alvarez of the Refugee Services of Texas which is aiding about 20 Valley trafficking survivors.

"A lot of them are very scared to go out of their home, if it's not work or to take their kids to school, because of immigration."

No statistics are available just for the Valley, but campaigners voice concern about more workers - especially those laboring on isolated ranches and farms - falling prey to traffickers with no access to help.

Attorney Libby Hasse from the Tahirih Justice Center in Houston described a case of a woman who fled El Salvador, where she had been targeted for being a lesbian.

She crossed illegally into the Valley with a smuggler who took her captive and demanded more money from her family.

"She was forced to cook and clean and take care of kids for several months," Hasse said. "Unfortunately it's something that we see fairly frequently."

A pregnant young woman from Mexico told police in the Valley city of San Juan that a smuggler had raped her and bound her with duct tape so she could not escape.

"You may not know you're being trafficked, but you then discover it when you arrive," said Alex Channer, principal analyst at U.K-based Verisk Maplecroft, a human rights data research company that studies labor abuse.

"You're owned and controlled by someone else."

U.S. federal authorities said they had received no reports of labor or sex trafficking cases in the Valley but blamed the silence on the traumatic nature of the crime.

"We have no evidence of it happening as far as our case work is concerned," said Carl Rusnok, U.S. Immigration and Customs Enforcement spokesman.

"(But) the whole issue of human trafficking is extremely secretive. It could be going on all around us."

UNDER-REPORTED CRIME

Stacie Jonas, an attorney with Texas RioGrande Legal Aid that has about 120 open or pending trafficking cases currently, said employers' threats grow more credible and frightening amid anti-immigrant rhetoric.

"People's fear of reporting is enhanced substantially ... It's driving immigrants underground, empowering bad employers," she told the Foundation.

Human trafficking, and labor trafficking especially, is notable for being under-reported, experts say.

Nationwide, some 700 criminal trafficking cases were open last year. Only five percent of the cases and about 100 victims involved labor trafficking, according to the Human Trafficking Institute, a legal and research group.

In the most recent statistics available, the U.S. government said it convicted 14 people of labor trafficking in 2016.

Globally, some 25 million people are estimated to be trapped in forced labor, according to leading anti-slavery groups, many of whom fell into the hands of criminal gangs while seeking to escape poverty or violence.

Many migrants fleeing brutal gang violence in Central America pay to enter through the Valley where smugglers can take advantage of the bustling commercial development and busy roadways, said San Juan Police Chief Juan Gonzalez.

"It's not a lot of open area so it's a lot easier to smuggle people," he said. "It's a lot easier to camouflage them."

Smugglers, known as coyotes, charge up to $12,000 a person. The steep cost makes migrants vulnerable to being taken captive to work off what they owe, experts say.

One former coyote named Eloy told the Foundation he used to ferry illegal migrants from the banks of the Rio Grande two miles (3 km) to a secret stashhouse in South Alamo in his pickup truck. A truckload of seven people earned him $1,400.

"Somebody told me, 'Hey, you want to help me? It's good money,'" he said, now out of smuggling and back to farming.

"Sometimes we make mistakes, but mine didn't catch up with me."

Migrants who managed to cross the river from Mexico become trapped in the Valley, unable to sneak past high-security government checkpoints further north, advocates say.

"You don't complain," said Tony Payan, director of the Mexico Center at Rice University's Baker Institute for Public Policy in Houston.

"You live in the shadows because you can be caught at any minute."

Funding for this story was provided by the International Women's Media Foundation

(Reporting by Ellen Wulfhorst, Editing by Belinda Goldsmith Please credit the Thomson Reuters Foundation, the charitable arm of Thomson Reuters, that covers humanitarian news, women's rights, trafficking, property rights, climate change and resilience. Visit http://news.trust.org)

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