Conan figures out that the murderer is Takumi Fuwa, the Domoto Hall director and former piano tuner for Kazuki Domoto.
The cause of the death of Hikaru Soma is revealed. Osamu Shida, Hisao Sone, Takehiko Renjo, and Yosuke Mizumi who were all from the same musical school Soma attended had forced Soma to drink although they knew he could not handle alcohol. Soma later died because of an accident that occurred because he was drunk. Hikaru Soma had a mother who never married, and his father was not known. It turns out that Takumi Fuwa was his father. Fuwa killed the four music students in order to get revenge for the death of his son. He used the flute parts (head, body, and foot) to throw off the police and lead them to think the murders was the job of a serial murderer who had 3 targets.
Fuwa's final plan was to destroy all the fans and musicians by setting up 24 bombs in the Music School. He set one bomb for each one of the 23 pillars holding up the building and one in the ceiling of the music hall. An air detecting sensor Fuwa had slipped into one of the pipes of the organ caused this off pitch note, making it flat. This sensor was connected to the bombs. With this method, he was able to detonate each bomb once the off note key was played on the organ. Since any one who had perfect pitch would tell the difference right away, Fuwa got rid of them by injuring Soko Kabe and attacking Reiko Akiba, and locking up Hans Muller, the organ tuner.
While Akiba interrupted Shion Yamane, Rara Chigusa, and Kazuki Domoto's performance by singing "Amazing Grace", Conan went to stop the last bomb from killing everyone in the musical hall. Although Conan had dissembled the senor and bombs, Fuwa was determined to set of the 24th bomb by directly pushing the detonator button in order to kill Kazuki Domoto. Miwako Sato shot the detonator out of his and Takagi arrested Fuwa. Fuwa felt that after his wife and son had died, the only thing that kept him going was was being the sole piano tuner for Kazuki Domoto, a famous, skilled pianist. However, When Domoto retired, Fuwa felt that Domoto was acting selfishly. In fact, Kazuki Domoto had retired because he felt that although Fuwa had learned to hear perfect pitch, Fuwa was getting old and was losing his hearing. At times Fuwa would fail in tuning the piano. Kazuki Domoto felt that to save Fuwa's pride he would give it up and convinced Fuwa to be the hall director instead. When Fuwa finds this out, he gives up his plans to commit suicide and regrets his actions.
It is later revealed that although Fuwa had the chance to kill Akiba, he stopped because her singing was pure and was able to warm the hearts of everyone. He also couldn't kill the fiance of his deceased son. Akiba had revealed that when she heard of Soma's death and the musicians that caused it, she wanted to kill them too, but the song "Amazing Grace" is about forgiveness and she chose to forgive them.