The four suspects are interrogated and searched. It seems everyone has a motive, but no evidence or murder weapon is found to pinpoint the killer. Conan does a little investigation of his own and finds a contact lens case outside the bathroom window and tinted contact lens in one of the mixing bowls. Just as the suspects pressures the police to let them go, Conan steps in reveal the trick was done by a sewing needle, string, and a ring to push the needle through and the only one wearing a ring is Nishitani.