Fifteen women arrested last month and accused of operating brothels out of Korean massage parlors in northwest Dallas were members of a multimillion-dollar prostitution ring, according to court documents.

The federal government filed a property forfeiture lawsuit last month against an alleged organizer of the sex-trafficking operation, which was made up of at least a dozen brothels, according to the U.S. attorney's office.

Fifteen women were arrested in last month's brothel sting.

Sun Im Mount, a 52-year-old from Plano, is the owner of the two properties that the government is trying to seize.

The government claims one of the properties, Home Town Day Spa at 2661 Walnut Hill Lane, is a known brothel that she owns with her husband, a 50-year-old radiologist. The other is a rental home in Carrollton.

The suit accuses Mount of collecting cash from the brothels in the prostitution ring and laundering the money through WinStar World Casino in Oklahoma and casinos in Louisiana.

The U.S. attorney's office says she used those illegally obtained funds to purchase the two properties in question.

A woman at the address listed for Mount, on Fullerton Drive in Plano's Kings Ridge development, would not answer the door of the home Sunday night.

But neighbors said that one day last month about 20 unmarked law enforcement vehicles lined the street. Authorities told them they were executing a search warrant at the home.

Homeland Security Investigations, the Texas Department of Public Safety and the Dallas Police Department began their investigation into Mount and the prostitution ring in March 2015, according to the suit.

It's unclear whether Mount faces any criminal charges because DPS and the U.S. attorney's office have declined to comment on the case. Dallas police also did not respond to multiple requests for comment.

Many of the massage parlors listed in the suit are still in operation, including Home Town Day Spa.

Authorities received information from a sex worker at Dallas Doll House in July 2015 that allowed them to tap the brothel's phone and record all numbers that called in. Over the following months, investigators monitored Mount's movement as she traveled to brothels in northwest Dallas and to WinStar casino.

From December 2015 to July 2016, Mount paid more than 100 visits to various brothels associated with the prostitution ring, authorities say.

During roughly the same period, she visited WinStar casino at least 33 times. On one occasion, she lost $148,000 in one sitting at a gambling table, the lawsuit says.

The suit alleges that at least two sex workers have identified Mount as responsible for delivering condoms to the brothels and picking up money.

The suit says WinStar casino investigators believe Mount and one of her associates, Su Jin Choi, a 59-year-old Farmers Branch woman, laundered more than $3.3 million through the casino over a few months. Mount had a total buy-in of almost $625,000 from August 2015 to January 2016, and Choi had a total buy-in of more than $1.9 million during the same period, the suit says.

Texas Workforce Commission records show that Mount received no wages from 2013 to the first quarter of 2016, according to the suit. Her husband, Cameron Mount, makes about $50,000 per year as a radiologist and receives retirement checks from the U.S. Department of Veteran Affairs and the U.S. Treasury Department, according to the suit. However, the Mounts deposited more than $300,000 into their bank account in 2013 and almost $150,000 in 2015.

According to the suit, the Mounts bought Home Town Day Spa in June 2015 with $20,000 cash and a $520,000 cashier's check. Choi and James Andrade, a 33-year-old Dallas man, manage the place. Andrade created a company called 2661 Hometown LLC (a combination of the massage parlor's street number and name) to conduct its business operations.

On multiple occasions, authorities have found Mount with thousands of dollars in her possession. During a traffic stop on Feb. 17, a Texas state trooper discovered a zip-close bag with around $8,500 and numerous condoms inside a blue, backpack-style purse that Mount had been seen carrying into brothels on different occasions. Customs and Border Protection officers found $20,000 in her and her husband's backpack on a Korean Air Flight on March 19.

On Aug. 26, police arrested the managers of eight brothels associated with Mount: Number 1 Spa, Green Spa, Home Town Day Spa, Dupond Studio, 7 Star Spa, Empire Spa, Gold One Spa and Dallas Doll House.

According to the suit, police believe four other illicit massage parlors are involved in the prostitution ring: Smile Spa, Hulahand, Moon Night and Elegant Spa, all in a building at 11308 Emerald St.

It is unclear whether Sun and Cameron Mount, Choi or Andrade will face criminal charges, though the basis for the federal government's suit is that the two properties owned by Mount were acquired through unlawful activity.

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