HOUSTON – Not many days after MS-13 members killed Adan Huerta in El Salvador in 2017 for opening a barbershop without their permission, Huerta’s sister, Monica, in Houston, was told, “You’re next.”

Four members of the gang in El Salvador and two in Houston sent Monica private Facebook messages warning her not to “get comfortable” because the “gringos” in the United States “can’t save you.”

Monica and her family moved, and she hired an attorney to help her apply for political asylum. She suspects MS-13 may be targeting her because she wired her brother money to help him open the barbershop.

“I want to believe that because I’m here in the U.S. nothing will happen to me, but things are starting to get a little scary now,” said Monica, who moved to this country from El Salvador decades ago. “If they don’t get their way, they will kill.”

Between 10,000 and 15,000 MS-13 members live in the United States, about 10 percent of whom, or 800-1,200, live in the Greater Houston area, the FBI estimated. The number is constantly fluctuating as members are deported and others cross into this country illegally every month.

“MS-13 continues to be an emerging threat here in the Houston area,” George Rhyne, administrator of Houston’s Texas Anti-Gang, or TAG center, said. “To establish this as a southern command and control point is critical for them to do business throughout the country.”

Dozens of investigators from 14 agencies based at the TAG center, an undisclosed location in the Houston area, focus exclusively, together, on major gang threats (full list of agencies below). The program is funded through the Office of the Governor’s criminal justice division, and the Houston TAG center was the first of six built across the state.

PHOTOS: El Salvador and the war with MS13

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Houston’s FBI Gang Task Force, based at the TAG, recently quadrupled the number of agents and officers dedicated to MS-13 investigations, Supervisory Special Agent Mark Sabol, who leads the elite task force, said.

From El Salvador, where the government estimated there are more than 40,000 MS-13 members, to Honduras, Guatemala, Mexico, and in more than 40 states in the U.S. where they operate, MS-13 is “one gang,” he said.

“I would consider them the only true transnational gang that exists,” Sabol added. “They actually communicate and take orders directly from El Salvador.”

Harris County has the “highest reported membership” of MS-13 in the state, according to the most recent declassified Texas Gang Threat Assessment. The gang is present in all the surrounding counties, the FBI added.

Border Patrol agents in Texas reported catching more MS-13 members attempting to cross the U.S.-Mexico border illegally in the first four months of 2018 than all of 2017.

In El Salvador, MS-13 and law enforcement are at war, with hundreds of homicides every month. The front lines of the fight against MS-13 in Greater Houston are mostly behind the scenes.

READ: A closer look at MS-13 in El Salvador

In addition to responding to brutal, and even satanic homicides across the region in recent years that have grabbed headlines, Sabol said his team “routinely” disrupts and prevents more brutal violence.

“If there’s a kidnapping, we often hear about it through covert or overt means,” Sabol said. “We’re able to stop the kidnapping that is simply a kidnapping and, it doesn’t turn into that homicide that was about to happen.”

The task force is on the streets of Greater Houston, almost every day, from Walker to Fort Bend County and beyond, almost every day gathering intelligence, conducting arrests, and disrupting criminal gang activity, usually undercover.

Members of the task force also travel to El Salvador every year, for weeks at a time, to train, advise and mentor Salvadoran law enforcement and to increase their own knowledge and skill in fighting the gang.

Salvadoran police also train in Houston, Los Angeles and Washington, D.C., as part of the Central American Law Enforcement Exchange, or CALEE, program. Cooperation between law enforcement everywhere tasked with fighting MS-13 is at unprecedented levels.

“We routinely talk to investigators based in Boston, in Northern Virginia, in Charlotte, in Florida,” Sabol added. “Our murderers are traveling throughout those cities.”

Monica and Adan Huerta are made-up names, for her protection. But her fear of MS-13 is so real, she worries the gang will find out if she talks to police about threats made against her. This is a persistent problem for the task force, other investigators at the TAG, and law enforcement generally.

“We don’t care about your immigration status, we don’t care about your socioeconomic status, whether you own a food truck or Fortune 500 company,” Sabol said. “If MS-13 is extorting you or harassing you, we want to know about it. We must know about it.”

While the conviction rate in El Salvador, MS-13’s headquarters is an abysmal 3 percent, “we’re substantially higher, for MS-13-specific cases,” Sabol said. “We’re almost at 100 percent in Houston.”

If you have been threatened in any way by MS-13 or any gang, visit stophoustongangs.org or call 1-800-FBI-TIPS.

Houston TAG center agencies: