Li Wutong held his breath and said, "No wonder, no wonder you said that the lounge on the third floor was not the scene of the first murder." ”

"And what is the lounge on the second floor?"

Wu Tongguang said: "I just went to the lounge on the second floor, and the layout of the lounge is basically the same as that on the third floor, but there is a slight difference, its windows are open. ”

"So the killer escaped through the window?"

Wu Tongguang said: "The murderer didn't enter the lounge at all. ”

"Huh? What's going on? ”

"Show me what you found on the roof."

Li Wutong took out a cylinder-like thing, this cylinder is very ordinary, and the appearance looks like the sewing cylinder used by ordinary people. Wu Tongguang gently unscrewed the lid of the cylinder, and there were a few lead needles left inside.

"This is the murder weapon."

Li Wutong said: "You mean that the murderer killed Professor Zhu with this thing......"

Wu Tongguang opened the tail of the syringe again, and there was a small machine spring inside, and with a slight press, the lead needle could be ejected from the syringe.

Li Wutong gently pinched the spring at the end of the barrel: "No, this elasticity is very weak, even if the needle is fed with poison, it is not enough to pierce the skin!" ”

Wu Tongguang smiled mysteriously and said, "Have you forgotten what Professor Zhu talked about today?" ”

"I remember the second student just now, that is, Bai Yuwen, said that Professor Zhu talked about today: 'A small object, falling from a high altitude, can form a force because of the falling distance of the high altitude and the acceleration of gravity, which is also the law discovered by Sir Newton.' ”

Wu Tongguang said: "That's right, it's gravity, these lead needles are fed with drugs that can stimulate heart disease, and these small objects, falling from a high altitude, using gravity acceleration, when they fall to the second floor, they already have the power to puncture the skin!" This explains why this syringe is on the roof! ”

"How did you know that the syringe was on the roof?"

"When I inspected the edge of the window, I found that there were several holes in the stone along the window, these holes were extremely subtle, and the same as the one on the top of Professor Zhu's head, which could not be easily found, this should have been left by the murderer during the test, and the murderer found that when the distance fell to the third floor, it was not enough to form a penetrating force, so he chose to commit the crime on the second floor, and the more the distance he landed, the greater the force formed by the falling of the object."

Li Wutong said: "I understand, so to speak, the murderer took advantage of Professor Zhu walking into the lounge on the second floor and poking his head out to close the window, and this lead needle bounced off the roof of the building, piercing the top of his head and causing his heart to move." ”

Wu Tongguang said: "That's right. ”

Li Wutong said again: "But how did the murderer calculate that Professor Zhu would stick his head out of the window?" ”

Wu Tongguang said: "This is easy, if someone calls me on the roof, I will also stick my head out to see." ”

"It's as simple as that?"

"This person should be someone that Professor Zhu is familiar with."

Li Wutong nodded in agreement. Wu Tongguang said again: "We have found the murderer's method of committing the crime, and we will explain another question below, that is, why Professor Zhu died in the lounge on the third floor, he was pricked by a needle, and there is no doubt that it should be the lounge on the second floor." ”

Wu Tongguang walked to the two-seater sofa and imagined the situation where Professor Zhu had fallen before.

Li Wutong said: "Could it be that someone carried it?" ”

Wu Tongguang shook his head: "Professor Zhu came up on his own. ”

Li Wutong said: "Since Professor Zhu can go up by himself, why can't he call for help?" ”

Wu Tongguang said: "Perhaps, he didn't pay attention to such a subtle needle prick, and there is a certain time interval between heart attack and sudden cardiac arrest." ”

Li Wutong groaned for a while, this killing method was too peculiar, she sorted out the situation in her mind, and suddenly thought of something: "Wu Tongguang, since the third floor is Professor Zheng's lounge, and the second floor is Professor Zhu's lounge, then in other words, someone deliberately wants to lead us to the third floor?" ”

"Yes."

"What's the reason for that?"

"That's why I judged that the diary was still in this building, because the murderer didn't have time to look for it! If you think about it, according to the situation at that time, Professor Zhu should have kept this very important diary for others, and the best way to hide a book-like item was to put it in this teaching building full of books and bookcases. What kind of place is Tianjin, it is one of the most powerful territories of the spy organization, since Lei Yin has been to Tianjin, it is inevitable that his meeting with Professor Zhu will not be known. ”

"Yes, if Professor Zhu hides in a place related to himself, someone may steal it." Li Wutong nodded.

Wu Tongguang said: "Wouldn't it be wonderful to hide in a person who has had a holiday with you, and that person has been away from school for a long time?" ”

Li Wutong clapped his hands and said, "This person is Professor Zheng Jiaye, that is, the owner of the lounge on the third floor." ”

"Then the identity of the murderer can basically be determined......

"You mean?"

Wu Tongguang said slowly: "After Professor Zhu got out of class, of course, he went back to his lounge on the second floor. If I didn't infer a mistake, it should have been: when he walked to the lounge on the second floor, he was 'accidentally injured' by a lead needle, and found that he had something wrong with his heart, and after taking the medicine he had brought with him, he became suspicious, so he insisted on going up to the third floor to check if the important diary was still there. ”

He paused for a moment, had already walked to the two-seater sofa, and continued: "Of course, the murderer is not so powerful, he can predict the prophet, we have always reasoned from our own thinking, so I think this case is very strange, in fact, the murderer just designed a trick of feeding poison with a lead needle, intending to kill Professor Zhu on the second floor, and then come to rummage through the lounge on the second floor." In order to achieve this, he deliberately took visitors to the lounge on the third floor to make time for himself. ”

"However, what I didn't expect was that Professor Zhu actually walked up by himself."

"Professor Zhu is so nervous about this place that does not belong to him, the diary should indeed be in the lounge on the third floor, and the murderer was self-defeating, so we arrived at the door of the lounge on the third floor first. If he didn't take the diary, he was naturally reluctant to leave. So, you can already tell me, who is the murderer? Wu Tongguang looked at Li Wutong.

"Needless to say!" A male voice came from the door of the lounge, and the light from the window shone through the whole lounge, and the man stood in the doorway, his face was full of shadows, but anyone could feel his murderous aura. Under the sipping of Su and Li, the man held a spear and aimed it at Li Wutong, and the muzzle of the gun was a little dazzling in the light.

"Is that you?"