Jang Yun-gi brutally murdered a high school student he had never met before. When and to what extent did his father, Inspector Jang, know about his son's crime? After the murder, Jang Yun-gi calmly visited a laundromat and got a haircut. When he was apprehended by the police and stood before the photo line, he even confidently revealed his face without a hat or mask. Is his father behind all of these incomprehensible behaviors shown by Jang Yun-gi? SBS YouTube channel Discovery of Knowledge posed these questions to Professor Bae Sang-hoon, the first profiler of the National Police Agency.

(Planning: Kim Soo-hyung | Host: Jeong Yu-mi | Writer: Park Jeong-rye | Editing: Kim Bok-hyung | Camera: Kim Sang-yoon, Hwang Se-hoe | CG: Jeong Yu-min | Director: Jo Do-hye | Produced by SBS Digital News)