At Agasa's house, Oomine reveals the gun he bought was supposedly filled with blanks and it was only used to scare Onda. After Onda was shot, he reveals he threw the gun away. Conan, Oomine, Ran, and Kogoro decide to search for the gun. Conan notices a dent on a wall and realizes where the gun landed. Conan reveals that the gun landed on an automatic window washer and was brought to the roof. After examining the gun, the bullets were confirmed to be blanks and that someone attempted to frame Oomine for the murder. Conan returns to the basement where the culprit attempted to shoot him and finds a part of a gun. While Kogoro is talking with the police and the three suspects, Oomine appears holding Conan and threatening to shoot him. The suspect Satoshi Kanda tackles Oomine down. Conan tranquilizes Kogoro and while impersonating him, reveals Kanda to be the murderer. Conan reveals Kanda planned the murder after hearing Oomine and the two suspects' plans. He directed Oomine to the gun site and was the one who sold Oomine the gun. As evidence, Conan reveals that Kanda was searching for Oomine's gun and due to the window washer, got detergent and dirt on his shoes. For more evidence, Conan reveals that while firing his gun at Oomine, his gun exploded cutting his finger. Conan gives the police the piece of the gun and reveals a bloodtest will confirm it is Kanda's blood.

The police cannot find where the poison originated. It turns out other customers all had motives to murder him!