Dark Figure of Crime

Amsusarin is a movie starring Yoon-seok Kim, Ji-Hoon Ju, and Jin Heo. A criminal Thriller about the fierce psychological confrontation between a detective and a killer who confessed to multiple murders.
A serial killer is caught for his seventh murder. A cop tries to solve the first six cases with the killer's help, but starts to suspect that he has ulterior motives. Based on a true story.