Conan investigates and after putting Kogoro to sleep , impersonates him and reveals the murderer to be Mikami .
Osamu 's assistant and son are suspects to the murder due to being the only ones with keys to the apartment .
Conan investigates and after putting Kogoro to sleep , impersonates Osamu and reveals the murderer to be Mikami .
Osamu 's assistant and son are suspects to the murder due to being the only ones with keys to the apartment .