Conan investigates and upon discovering the method, tranquilizers Kogoro and explains how Hoshie committed the murder. He explains the burn marks on Hoshie's napkin indicate cyanide was on the napkin and the poison was placed on a lemon slice. Conan elaborates explaining how Taruto was famously known to hate sour things, and had planned to surprise his guest by eating sour food with the use of synsepalum dulcificum. Upon testing if the synsepalum dulcificum was still in effect, Taruto ate the poisoned lemon slice. While down, Hoshie took the lemon and placed the medicinal wafer in her husband's mouth and hid the lemon slice among the others during her fall. Conan concludes that Hoshie's fingerprint and Taruto's saliva should be on the poisoned lemon slice. Hoshie confesses revealing her motive is revenge for her former boyfriend who Taruto pushed to suicide.