The young policeman cautiously glanced around at the reactions of the seniors present, and then continued: "So I guess the deceased may have been left-handed. After saying his judgment, the young policeman turned his attention to Wang Shen again.

Wang Shen also looked at the young policeman. Suddenly, a smile appeared on Wang Shen's face, and his hands applauded lightly. "Xiao Liang is not wrong at all." After Wang Shen said this, everyone present turned their eyes to this young policeman, full of surprise.

"The day before the deceased died, I also talked to the deceased. It's mainly about San's traffic fatality and the murder of a bar girl in an alley. Some of you here should also know about these two cases, but because the time is too rushed, I haven't had time to explain them to you in detail. When this case is over, we'll work on it together. Well, let's go back to Song Mu, the deceased this time. When I talked to him, I noticed that he used his left hand to write and drink. Based on this, it is inferred that he should be a left-hander. And I also deliberately observed that after he drank the water, the position of the cup was also placed on the left-hand side. So, if you look at this picture, the cup is placed on the right hand side, which is very strange. Such a situation may illustrate a problem. Wang Shen didn't continue, but sold a pass, and glanced at the people present, hoping that one of them could provide the next reasoning of the case.

Everyone looked at each other and didn't say a word. Wang Shen looked at the young policeman and pointed at him with his finger: "Xiao Liang, the next judgment is still up to you to tell your opinion." ”

When the young policeman heard Wang Shen directly call his name, he nervously immediately stood up from his chair and replied "yes!" "Explanation, indicating that the last user of the cup was not the deceased, but was later placed on the desk by someone else. If we analyze it from this point, it is very likely that the person who placed the cup at the end is the murderer. His purpose in setting the cup was also to induce us to believe that the deceased had died by suicide. However, there is a contradiction here. The young policeman paused, his eyes looking at Wang Shen, as if hesitating whether he should say his own judgment.

"It's okay, you can say whatever you want." Wang Shen saw the young policeman's doubts. Wang Shen smiled kindly at the young policeman, trying to dispel his worries and doubts.

The young policeman looked at Wang Shen and nodded. Judging by the placement of the cups, the murderer should not have known that the deceased was left-handed. Therefore, the murderer should not know much about the deceased. However, this contradicts the confession book on the computer. If the confession was not written by the deceased himself, then it is very likely that it was written by the murderer. Judging from the content of the confession, the murderer should be a person who knows the deceased very well. I really can't figure out such a contradiction. The young policeman frowned, his eyes fixed on the photograph on the projection screen, and he was completely immersed in the reasoning of the case.

"You do have a point." Hearing Wang Shen speak, the young policeman sat back in his chair. "Xiao Liang, but you ignored a criminal psychological problem." Wang Shen looked at the young policeman, then at the people present, and smiled.

"Xiao Liang, if you were asked to kill someone now, would you be nervous?" Wang Shen's topic changed, which made the young policeman a little overwhelmed.

"Huh?" The young policeman immediately stood up from his chair again, glanced at Wang Shen suspiciously, and then quickly understood what Wang Shen meant. "It should be nervous." The young policeman replied calmly.

"Yes. People are most prone to mistakes when they are very stressed. Even if the murderer is very aware of the deceased's habits, under extreme stress, people will operate things according to their own way of life. For example, where this cup is placed. As we all know, our habitual thinking is to put the teacup on the right hand after drinking. After listening to Wang Shen's judgment, everyone seemed to have a feeling of sudden realization. However, these are based on the premise that the murderer is the first time to commit the crime. How can I judge the number of times the murderer has been committed? Let's take a look at this picture. ”

Wang Shen clicked on the projection screen, and a photo of a plastic bag appeared on the projection screen. The plastic bag was placed very large, and if you looked closely, there was a hair in the plastic bag. "This hair was found between the fingers of the deceased at the scene. At that time, the deceased pinched the hair very tightly. I think the deceased must have been trying to send us some message. If my reasoning is correct, this hair should be from the murderer. I had the hair biologically examined, and then compared it to the criminal gene pool we had on file, and I didn't find a match. It shows that this murderer has no previous convictions. That's why I judged that the murderer should be the first time to commit murder. ”

Wang Shen tapped the projection screen again, and a close-up of the cup on Song Mu's desk appeared on the screen. "So, based on the above judgment, I think it is more likely that the deceased was killed. Please take a look at this cup again, this cup is the water cup used by the deceased before his death. When I was talking to the deceased last night, I saw the deceased drink water from this cup. And today at the crime scene, I found that there was still half a glass of water left in the cup. So I had the water and cups tested separately by the people in the identification department. I was a little surprised by the results of the examination, neither the water nor the mouth of the cup detected a single trace of saliva from the deceased. May I ask you, why does a normally used cup not have a trace of saliva left in a short period of time? Wang Shen turned to the side and looked at everyone present.

"Unless someone has washed the cup and washed it very carefully." A middle-aged policeman sitting on the right side of the conference table spoke his judgment with a serious face.

"Yes, I think that's the reason too. That being the case, we now have two issues that need to be addressed. First, who washes the cups? Why wash this cup? Second, after washing the cup, why do you have to pour half a glass of water again? Wang Shen said as he walked to the whiteboard on one side and briefly wrote down these two questions on the whiteboard.

Wang Shen's eyes skimmed over everyone's faces one by one, and finally stopped at the young policeman. Wang Shen looked at the young policeman and smiled, and the young policeman immediately understood and stood up from his chair again. "I think there are two possible scenarios depending on the person washing the cup. First, the person who washes the cup is the deceased. The reason why the deceased wanted to wash the cup was because he wanted to drink water, but the deceased found that his cup was dirty. But why are cups dirty? There may have been some other liquid in the cup before this. Such an assumption is very consistent with the deceased's almost hygienic personality. But why didn't the deceased drink the water after pouring it? It may not be too late to drink...... No, this assumption is unlikely, because as mentioned earlier, the deceased was left-handed......"