When Yokomizo Sango was questioning other people, Aizen said to Conan: "Conan, have you solved this case?"
"Not yet."
Conan replied, and then said: "Why, have you solved this case?"
"I'm sorry, you are right."
Aizen smiled slightly, patted Conan's shoulder, straightened up and said to Yokomizo Sango: "Officer Yokomizo, I have solved this case."
"Oh? Really?"
Yokomizo Sango was cheered up and very happy when he heard this. Because Aizen was a disciple of Mouri Kogoro, he did not doubt whether Aizen was really capable of solving this case.
Aizen nodded, and after everyone looked at him, he said, "The secret is in the telephone recording. Just take a tape like the one in the phone, pull out the tape from this tape to a sufficient length, and then attach it to the phone. Of course, the pulled tape should still be placed outside. The next thing to do is to straighten the pulled tape and go outside the door."
"I see!"
Hearing this, Conan suddenly realized that he knew the criminal's method and who the criminal was. However, after understanding this, he was quite annoyed. He didn't think of this earlier and was one step behind Aizen. It was really wrong.
"Put the tape through the circle on the key, then pull out a sufficient length of tape. Leave the key outside and take the pulled tape back to the room where the key fell. Arrange three chess pieces of the same height to form a triangle. Place one end of the tape on the chess piece closest to the phone, and then place the notebook on the chess pieces..."
"Mr. Aizen, please wait a moment."
Yokomizo Sango suddenly stopped. He thought for a long time, and after sorting out Aizen's words, he said, "Mr. Aizen, I think I understand what you mean. You want to use the force of pulling the tape to knock over the chess pieces, but that won't work at all. The base of the chess piece is very stable. Before it falls, the key will knock the chess piece down and be pulled out of the notebook."
"Officer Yokomizo has hit the nail on the head, but please listen to me finish."
Aizen smiled and continued, "As for the problem Officer Yokomizo just mentioned, turn the chess pieces upside down. Although the heads of the pieces are round, as long as they are made of cardboard like the notebook, the structure can be stabilized."
Aizen continued, "Then, just walk to the door and close it, put the key on the ground, make a call, and when the telephone recorder is started, the tape will be pulled in, and the key will be used." The key will pass through the crack under the door and land under the notebook placed in the center of the room. After hitting the chess piece, the key will be pressed under the notebook. "
"I see," Sango Yokomizo thought for a moment before saying, "So that's how it is. So, as long as the phone recording system is in use, the tape will be pulled back, and the evidence will disappear."
He then looked at Shirakura and said, "Mr. Shirakura, you're the culprit, aren't you?" Sango Yokomizo was no fool. At this point, he naturally knew that Shirakura Akira, who had left behind ten recorded phone calls, was the murderer.
"How is that possible? I didn't kill anyone."
Shirakura's forehead was slightly sweaty, but he seemed to force himself to remain calm and said, "This is all just Mr. Aizen's reasoning. Maybe his reasoning is completely untenable. Officer, how can you say I am the criminal after listening to his reasoning?"
Upon hearing this, Yokomizo Sango immediately said to a police officer beside him: "Go buy a tape that matches this phone."
"No need, Officer Yokomizo."
Aizen stopped him and said with a smile: "According to my observation, this should be a sudden crime, not a premeditated crime. Therefore, the criminal would not have time or no way to take fingerprint precautions when he was getting the tape. There must be the criminal's fingerprints on the tape now. We just need to compare the fingerprints."
Hearing this, Yokomizo Sango looked at Shirakura Yang and said: "Mr. Shirakura, even so, you are not going to admit it?"
Shirakura Yang lowered his head and said after a long time: "No, I admit it, yes, I killed Mr. Hirota."
Aizen didn't care at all about the reason why Shirakura Yang killed Masami Hirota. After Shirakura Yang admitted that he was the murderer, he found Yokomizo Sango and told him that he was here tonight to pick up the disk with the photos, and asked if he could take the disk back.
Yokomizo Sango refused Aizen's request, stating that although Aizen had helped him solve the case, the disk was part of the evidence and could not be taken away. He could only take it after the case was concluded.
Aizen expressed regret at this, but smiled slightly inwardly. He had never intended to take the disk with him in the first place. Taking it would do him no good. If Haibara Ai developed an antidote and restored Conan to Kudo Shinichi, it would not only be of no benefit to Aizen, but would also likely alienate Ran Mouri. Therefore, he had long since decided not to openly take the disk
.It was a good thing that the disk was taken by Yokomizo Sango. Aizen had already decided to take it secretly, so there wouldn't be any worry about it falling into Conan's hands. Even if Ai Haibara conducted research, she wouldn't be able to develop an antidote quickly without the necessary documentation. By the time the antidote was discovered, he would have already captured Ran Mouri, and by then, whether the antidote was successful or not would be irrelevant.
Conan was displeased at not being able to retrieve the disk immediately, but he had no other choice and could only accept the outcome.
With the case solved, Aizen, Conan, and Ai Haibara bid farewell to Sango Yokomizo and drove off back to Tokyo.
On the way, Ai Haibara expressed surprise at Aizen's deductive abilities. While she hadn't known how powerful his deduction skills were, she was surprised that he had solved the case before Kudo Shinichi, known as the Sherlock Holmes of the Heisei era. This showed that, while Aizen might not be as skilled as Kudo Shinichi, he was at least as good, and that was enough to astonish her.
Upon hearing this, Aizen smiled and said that if he had the chance next time, he would show Haibara Ai his other abilities, so that she would know that the so-called Black Organization wasn't so invincible and could still be defeated.