Complaint shows how Bloomington prostitution ring operated

BLOOMINGTON, Minn. (FOX 9) - Three suspects are wanted on charges of promoting prostitution after Bloomington police uncovered a sex trafficking operation last year, a new set of criminal complaints detail.

Prostitution ring uncovered

What we know:

Kewon Koo, 29, Douglas Tran, 32, and Hyesun Kim, 43, all face counts of promoting prostitution of an individual and receiving profit from prostitution in the case. Koo and Kim have listed addresses in Lewisville, Texas, while Tran's address is listed as Roseville, Minn.

All three suspects were charged via warrant. Authorities say Koo and Kim are currently in federal custody on an immigration hold. Tran is not in custody and authorities worry he could be a "flight risk."

A fourth individual is also named in the complaint, the person who supposedly rented out the apartment, but it's unclear if they've been charged.

The backstory:

Police began investigating the prostitution ring in October 2024. The operation was based out of an apartment building along 80th ½ Street near the Red Lobster in Bloomington.

Officers were told that men would routinely get buzzed into the apartment and typically stayed between 30 minutes to an hour per visit.

Investigators found a phone number registered for the renter was also attached to a listing on a prostitution advertisement website. 

In November, the apartment management notified police that a potential client had been buzzed into the apartment. As the man was leaving, police stopped him. Speaking with officers, the man admitted he had paid for sex at the apartment building.

In spring 2025, Bloomington police set up a sting, with an officer posing as a client and arranging a meet-up. The officer agreed to pay $400 to spend an hour with one of the workers.

Victims talk to police

What they're saying:

At the building, investigators found two women working out of the apartment. The women told police they would charge $400 per hour and had to pay $130 of the money to Koo, the booker. Inside the apartment, officers found lube, towels, a ledger, several cell phones and more than $13,000.

The women said they had been picked up at the airport by Tran, driving a white Tesla. Police later learned that Tesla had stopped at the airport 15 times between April 20 and the day of the bust. Police say video from May 29 showed Tran picking up one of the victims from the airport.

The women said they were forced to work even when they didn't feel well and outside their normal "business" hours, which ran from 9 a.m. to 9 p.m.

The women said they'd see about 10 men every day or two. A third woman had also been working out of the apartment, but she had left the previous week.

Operation moves, gets raided

Arrests made:

After the sting, building management alerted police that Koo had said they were moving out of the building. Police later learned in June the operation had shifted to a new apartment off 33rd Avenue, just south of the airport in Bloomington.

At the new apartment, police approached another suspected client, who admitted to paying $400 for an encounter with a woman in the building. In August, police raided the new apartment, and again spoke with two new workers. Those victims shared similar details about the arrangement between the suspects and the workers.

Koo and Tran were arrested shortly after the bust. Speaking with police, officers say Tran admitted to his role in the operation, but claimed to get all of his instructions from Kim – who was also known as "Hannah." Tran claimed to have been the first customer of the operation in 2022 and was asked by Kim to drop a worker off at the airport. Kim then kept recruiting Tran for other jobs, including picking up supplies and collecting cash from the operation. Tran claimed to have deposited between $50,000 and $125,000 into Kim's account over the last couple of years.

Kim was arrested on August 6 at a storage locker connected to the case. Kim had a New York ID under the name of "Woohee Chun."