A billiard room in Cheonan, South Chungcheong Province.

As police rush in, they arrest a woman.

[Police: As of this time, we will execute the arrest warrant, and three people are violating the Narcotics Control Act...]

This is a Vietnamese national in their 20s, identified as A, who served as the mastermind behind smuggling narcotics from overseas to sell and distribute them domestically.

A is accused of bringing in narcotics such as ketamine and ecstasy via international mail from a Vietnamese person living in Poland and distributing them.

An additional 40 grams of ketamine and 10 ecstasy pills were found at A's residence, and police tracked down accomplices one after another based on A's statements, forensic analysis of mobile phones, and account transaction records.

As a result, from October of last year to August of this year, 35 people were arrested for violating the Narcotics Control Act and other charges, among whom 15 were detained.

Among the 35 individuals caught, 24 were Vietnamese illegal residents who had entered the country on student visas and stayed even after their authorized periods of stay expired.

Seven South Koreans, including five naturalized citizens, were also caught on charges of using narcotics.

It was confirmed that they traded drugs through an overseas messenger used by Vietnamese nationals to evade police crackdowns.

The drugs traded in this manner were mainly distributed at Vietnamese karaoke bars located in Busan, Ulsan, Changwon, and South Chungcheong Province.

According to the investigation, the business owners provided the places and tools for administration, and customers or hostesses used drugs there.

[Jung Won-dae / Chief of the Narcotics Crime Investigation Division at Busan National Police Agency: (The investigation team) used internal information to conduct an undercover transaction, and after receiving a tip that drugs were being secretly administered while listening to music inside Vietnamese establishments, we launched a crackdown.]

The narcotics seized by police in this investigation amount to 17.67 grams of ecstasy and 48.7 grams of ketamine, an amount that can be administered to about 8,000 people.

Through this investigation, the source of 199.55 grams of ketamine seized by customs was also identified, but the mastermind who supplied the drugs from overseas has not yet been caught and remains wanted.

Believing that there may still be supplies remaining nationwide aside from the seized drugs, the police plan to continue their investigation based on the apprehended suspects.

(Reported by Kim su-yun, Video by Kyungmun, Video Editing by Park Na-young, Photo courtesy of Busan National Police Agency, Produced by SBS Digital News)