Arthur Patterson, 17 at the time of the incident (born to an American father and a South Korean mother), was the main suspect.
After the rest of the group went back to the 4th floor, Patterson and his friend Lee went to the bathroom, where they coincidentally came in contact with Jo Jung-Pil and stabbed him 9 times in the carotid artery using the knife.
On April 4, the Department of the Army Criminal Investigation Division (CID) received an anonymous report and arrested Patterson.
The Supreme Court of Korea ruled that "the relationship between the negligence of the prosecutor and the bereaved families of the mentally damage is recognized".
[This quote needs a citation] Prosecution of Patterson was requested by Jo Jong-pil's family, after the film The Case of Itaewon Homicide was released, due to high public demand, another judgement had to be made.
In 2009, the film adaptation of The Case of Itaewon Homicide and SBS's program I Want to Know It broadcast an episode multiple times and interest in the topic renewed.
Patterson left the country once he was judged innocent on other charges, it remains a controversy whether the statute of limitations was stopped in the legal community.
[10] After investigation by South Korean prosecutors it was said they were accomplices and Patterson killed the victim, and Lee instructed the murder.