The Beast (2018)

This is the 2018 movie [The Beast] starring Kim Yun-seok and Ju Ji-hoon. 'Amsu Sarin' (literally 'hidden murder') refers to a murder case where there is a victim but no report, body, or investigation, thus remaining unknown to the world. The movie is based on the Lee Doo-hong case, which was actually broadcast on the investigative journalism program 'Unanswered Questions' (there was an incident where the victim's family protested and filed an injunction against the screening, which was eventually resolved after the production company apologized). Instead of the typical progression of a murder case leading to the pursuit and arrest of the perpetrator, this unique film begins when Kang Tae-oh (Ju Ji-hoon), already imprisoned for other crimes, confesses to Detective Kim Hyung-min (Kim Yun-seok) that he has killed seven people. The main plot follows Detective Kim Hyung-min as he tries to uncover the truth amidst Kang Tae-oh's confession, desperately attempting to bring closure to the victims of cases no one else cares about. You could say it's a work that aimed to showcase a fierce battle of wits and respect for the victims, excluding sensational action and melodrama.