Yoo Ah In (real name is Um Hong Sik) returned home in the early morning of May 17 after being interrogated for 21 hours by the drug crime investigation unit of the Seoul Metropolitan Police Agency. Yoo Ah In was summoned as a suspect at 9:00 am on May 16.

The interrogation of Yoo Ah In lasted until around 4:40 am. After spending nearly two hours reviewing the records, he left the building at 6:26 am.

When reporters asked Yoo Ah In about his interrogation, he apologized for the inconvenience but did not address the allegations of cocaine use, the reason for changing the attendance date, or the method of drug purchase.

The police suspect that Yoo Ah In used five different types of drugs: hemp, propofol, cocaine, zolpidem, and ketamine. They are investigating the specific drugs used, the source of acquisition, and potential accomplices.

In February, the police received a lab report from the National Institute of Scientific Investigation indicating the presence of four narcotic components (hemp, propofol, cocaine, and ketamine) in Yoo Ah In's hair and urine. It was also discovered that Yoo Ah In has been prescribed zolpidem, a psychotropic drug, for non-medical purposes.

Yoo Ah In was originally scheduled to appear for investigation on May 11 but declined to proceed due to the presence of a large number of reporters. In a subsequent incident in March, Yoo again postponed his summons upon discovering that reporters had become aware of the scheduled date.

A day prior, the police also summoned an acquaintance of Yoo Ah In, identified as 'A,' a writer who graduated from an art college. The investigation into Mr. A lasted until the following morning as well. It is worth noting that earlier, the police had booked four individuals, including Mr. A, as suspects for their alleged involvement in assisting or administering drugs to Yoo Ah In.

Upon concluding the investigation into Yoo Ah In, the police will assess whether to proceed with an application for an arrest warrant for the actor.