Case Closed - Season 1 Episode 645

The police reveal poison was only found on the victim's left thumb and forefinger causing them to be dumbfounded on how the poison was applied. Conan asks the police what possessions the suspects have and eventually realizes how Saizu was killed. He tranquilizes Kogoro and reveals Atsushi Tanaka, Saizu's barber, as the culprit. He explains how poison is applied on the rim of the victim's glasses during his haircut. When Saizu cleaned his glasses due to condensation, the poison got onto his hand and into his mouth when he broke the chopsticks. After Saizu died, Tanaka exchanged his glasses with the victim's to hide the evidence. Tanaka confesses and reveals he murdered Saizu in the restaurant in order to have it close down and remodeled for greater success. A month later, the ramen restaurant reopens in a new location and becomes popular after changing its slogan.