There are red flags common in human trafficking cases. Here's how the Florida spas compare

While only one person has been charged with human trafficking tied to a string of Florida spas shutdown last week, police say it is "manifestly obvious" trafficking occurred, and the red flags present in Florida are similar to those experts describe in a variety of other cases.

Martin County Sheriff William Snyder said Tuesday that police will need cooperation to bring more charges of human trafficking but that police believe trafficking did occur.

“I need one of these women, under the patient and legal care of a public defender, to tell us exactly how it is that they’re coerced, what is it that keeps them from running out into the street and asking for help,” Snyder said.

Ten spas in Florida are part of a multi-county investigation that has lead to hundreds of charges tied to prostitution. Most prominently, New England Patriots owner Robert Kraft allegedly paid for sex acts twice at a spa in Jupiter in January, police say. Kraft has pleaded not guilty to two charges.

Police have released some details on the conditions the women faced and what victims have told them.

Polaris, a nonprofit that operates the National Human Trafficking Hotline, identifies a variety of common indicators that trafficking may be occuring. While the list is not exhaustive nor is it exclusive to sex trafficking, and not all indicators were allegedly present in Florida, many of those listed are similar to what officials have described taking place:

More: Florida sheriff: 'Manifestly obvious' this is human trafficking, but need victim cooperation for case

'The individual(s) in question is not free to leave or come and go at will'

"These girls ... can't leave and they're performing sex acts," Vero Beach Police Chief David Currey said.

Police said none of the women had their own vehicles or could leave on their own.

"These people truly are stuck," Currey added.

Officials in Indian River County also said detectives watched multiple women with suitcases be transported to and from the spa, "for the purpose of sexual servitude," according to an arrest warrant.

The full story: Florida human trafficking ring, prostitution in massage parlors

Some stayed for days, others for months, according to police.

In Martin County, Snyder similarly said the women had no access to their own transportation and were moved from location to location.

One of the women, Lixia Zhu, 48, who is currently jailed on several charges, including racketeering and money laundering, told police her passport was taken from her, Snyder said.

'The individual(s) in question works excessively long and/or unusual hours'

"These girls are there all day long, into the evening," Currey said.

More: It's not just the Florida spa investigation allegedly tied to Robert Kraft. Sex trafficking is rampant across US

'The individual(s) in question is not allowed breaks or suffers under unusual restrictions at work'

Vero Beach Police Detective Sgt. Phil Huddy said of the women, "If they did show their faces outside the establishment, they were outside for a brief period of time, and they were within earshot or eyeshot of Lanyun Ma."

Ma, a 49-year-old Orlando woman who ran East Spa in downtown Vero Beach, is the only person charged so far with human trafficking. And it's not her first arrest: Oxford, Massachusetts police charged her with similar offenses in a 2011 investigation into a "health center" in the Worcester County town that detectives said was a front for a human-trafficking operation. Ma eventually pleaded guilty to a reduced charge of solicitation for prostitution and was placed on three years probation.

“They just kind of shuffle the girls in and out," Oxford Police Chief Anthony Saad told "They move. They change their [business] names, their locations. They are hard to keep track of.”

'The individual(s) in question owes a large debt and is unable to pay it off'

Currey said many of the women came from China on temporary work visas, indebted to the the brokers who helped them reach America.

More: Sex trafficking, prostitution is anything but a 'victimless crime,' experts say

'The individual(s) in question was recruited through false promises concerning the nature and conditions of his/her work'

Many of the women believed legitimate jobs awaited them, Currey said. Some answered what they thought were legitimate ads for masseuse jobs, but soon were pressured into doing more, police said.

Snyder said Zhu told police she came to the United States to work in a nail salon with a promise of high pay. She said she started in a nail salon business in Chicago a few years ago.

“After a period of time she found herself being forced into the sex trafficking,” Snyder said.

'The individual(s) in question is living and working on site'

"It was clear that multiple women were working and living inside the spas. They were cooking on the back steps of the business," Snyder said. "They were sleeping in the massage parlor on the massage tables."

In Indian River County, a health department employee conducting a routine inspection reported concerns after seeing clothing, suitcases, food, bedding and other signs people were living inside one of the spas, prompting the Sheriff’s Office investigation.

Huddy said the women lived in a small room with two mattresses on two-by-fours, using a makeshift shower and cooking in a small unsanitary room.

'The individual(s) in question is fearful, anxious, depressed, submissive, tense, or nervous/paranoid'

Police said the women were shamed, intimidated and taught not to speak to law enforcement or immigration officials.

Snyder said that when authorities interviewed Zhu, "she was overcome with emotion and broke down sobbing."

"It was tragic to watch, it was gut-wrenching for me," he added.

Zhu told authorities that she worried she would put relatives in China in jeopardy if she cooperated. She also said that at one point, a man involved with a gun intimated he’d use it.

"She was clear that she was in fear for her life," Snyder said.

Other signs of human trafficking

While there are common patterns to trafficking, only the specifics of each case show whether trafficking occurred, experts say.

"It's less about the what, and it's more about the how," says Chris Muller, director of training and external affairs at Restore NYC, which combats sex trafficking and works with its victims in New York.

There are more than two dozen kinds of human trafficking around the world, and while a blinking neon light at 2 a.m. in a Florida strip mall may be a red flag, it's important people can identify other cases, too, says Rebecca Bender, a sex trafficking survivor who works with victims.

"Are you also missing the red flags of the children in your kid's school" potentially being trafficked, she said.

"We do not have to see handcuffs and duct tape for trafficking to exist. It does not match the stereotypes that most people have from the movies," Bender says. "We don't have to be shackled. We're trapped due to fraud and coercion just as much as force."

While the physical signs may differ across cases, Bender and Muller say the coercion and exploitation of vulnerable people is present in all trafficking cases.

"No matter which different form it is, traffickers groom their victims. They're looking for vulnerable people," she said.

To learn about other common indicators of sex trafficking, not just those allegedly present in the Florida spas, visit Polaris' website.

Need help? See something?

The National Human Trafficking Hotline is confidential, toll-free and available 24/7 in more than 200 languages.

  • Call: 1-888-373-7888

  • Text: “BeFree” (233733)

  • Chat:

Contributing: Mary Helen Moore, Will Greenlee, Ali Schmitz and Dacia Johnson, Treasure Coast Newspapers; Cara Kelly, USA TODAY

This article originally appeared on USA TODAY: There are red flags common in human trafficking cases. Here's how the Florida spas compare