Reports have surfaced of the involvement of actor Lee Sun Gyun in drug-related activities, amid a major drug trafficking investigation in South Korea. 

According to an Ilyo Newspaper report on October 24, Lee Sun Gyun's drug usage was uncovered during a crackdown on domestic drug distribution networks.

An unnamed female employee from the entertainment industry referred to as 'A,' who is allegedly reported to have used drugs with the actor, was caught. During this investigation into 'A,' Lee Sun Gyun's involvement was revealed.

Experts involved in drug trafficking investigations believe that Lee's name most likely emerged while the police scrutinized 'A's financial records. Officials from the drug enforcement agency revealed, "It's not uncommon to identify parties involved in drug usage while tracing financial transactions linked to drug deals."

It's alleged that Lee Sun Gyun had been repeatedly using drugs, including marijuana, at 'A's residence located in Gangnam, Seoul. After expanding their investigation, the police added more charges to the actor, as they confirmed that Lee Sun Gyun was found to have used not just marijuana but also other undisclosed drugs.

Lee Sun Gyun now faces a likely search and seizure operation via a court-issued warrant and is expected to be summoned for investigation as soon as possible.

However, Lee Sun Gyun has asserted that he has been victimized by 'A' and was blackmailed to pay over 300 million KRW (233,000 USD). He subsequently filed a criminal complaint against 'A' and two accomplices in this alleged extortion case. Authorities recently passed this case to the local police for further processing.

Previously treated as a key witness, Lee Sun Gyun has now been formally classified as a suspect. Besides Lee, other individuals who were earlier questioned as witnesses in the widening drug investigation included Hwang Ha Na, the granddaughter of a conglomerate family, and Han Seo Hee, a former pop idol trainee.