A Small Client (2) Meitantei Conan : Season 1 Episode 355

The forensic team reveals that Kamoshita was knocked on the head with a shower nozzle knocking him unconscious and was later strangled. While the police are watching a videotape found in Kamoshita's room, Conan notices that the movie ended two minutes earlier than the time indicated on the box and realizes how the murder is done.