After going over the characteristics of the boy, Conan realizes who it is. During the midnight snack, Conan uses Mouri to solve the case. Conan reveals the boy who was honest would never have taken the money. He reveals the identity of the boy to be the butler, Taisuke Houya; The boy's nickname was revealed to be "gari" because he liked to eat Gari. Later, Kiyonaga barges in and accuses one of the men with the scar as a serial killer from a past case. The man reveals that he copied the scar from a strange man a few years ago whom they realize is the serial killer. The next day, a criminal psychologist named Douji Hiramune challenges the serial killer to reveal himself. He happens to leave in the same apartment as Ayumi where the Junior Detective League are staying with. Ai later reveals to Conan she saw a mysterious man whistling Let It Be> which is the serial killer's trademark.

Later, Takagi comes to the conclusion that Kibo Dokurou is the serial kller. Conan notices something is strange about Hiramune's dying message, and realizes his message indicates the person who murdered him was a copycat killer. Conan reveals to Sato that Hiramune was actually the serial killer from the past. Conan reveals that Nabei Eiki is the murderer. Takagi who was ordered to bring Eiki to the police station was taken hostage by Eiki. Takagi is shot in an attempt to subdue Eiki from shooting the police. Takagi is later revealed to be saved by a mahjong tile in his shirt pocket.