He drove the car and drove quickly to the county public security bureau.

As soon as he arrived at the gate of the police station, he happened to bump into Xiao Chen, who came out of his face, Xiao Chen also looked at Jiang Yu who was returning in surprise, and asked in surprise: "Deputy County Magistrate Jiang, why are you back?" ”

Jiang Yu asked, "Is Lao Li gone?" ”

"Nope." Xiao Chen shook his head and looked at Jiang Yu puzzled.

Jiang Yu immediately said, "Take me to see him." ”

Although Xiao Chen didn't know why, Jiang Yu wanted to see Lao Li in a hurry, so he still took Jiang Yu to see Lao Li, who was about to go out.

Lao Li looked at Jiang Yu who came back suddenly, and asked, "Deputy County Magistrate Jiang, why are you back?" ”

Jiang Yu waved his hand and said, "Find me a megaphone." ”

"Megaphone?" Lao Li looked at Jiang Yu puzzled and asked, "Deputy County Magistrate Jiang, what do you want the megaphone for?" ”

Jiang Yu didn't have time to explain to them now, but said: "You bring the megaphone first, and you will know what it is for in a while." ”

Lao Li has been in contact with Jiang Yu for a while, although he has no rules to do things, but he is quite reliable, so he didn't say anything, and told Xiao Chen beside him to get a megaphone.

A moment later, Xiao Chen came back with a megaphone and handed it to Jiang Yu.

Jiang Yu immediately took out his mobile phone and put it on the desktop, turned on the megaphone again, and then clicked on the recording.

Lao Li frowned and watched Jiang Yu's series of movements, but still listened carefully to the recording on the phone under Jiang Yu's instructions.

This recording is what they heard before, that is, the conversation between Zhang Xianzhen's wife and the murderer.

After listening to that conversation, they didn't notice anything unusual, could it be...... What did Jiang Yu hear through this conversation?

Lao Li listened patiently, and under the effect of the megaphone, the original sound was constantly amplified, just like looking at the underwater world under a microscope, and the subtle sounds became extremely clear.

Even the sound of fingers rubbing against the screen of the phone is incomparably clear.

At this time, Lao Li's eyes widened, he looked at Jiang Yu on the side in disbelief, raised a finger with some excitement, and pointed to his mobile phone: "Deputy County Magistrate Jiang, this person ...... This man ......"

Xiao Chen looked at Jiang Yu who nodded in confusion, completely unaware of what they were talking about.

Lao Li turned around and kindly mentioned Xiao Chen: "Xiao Chen, haven't you found out?" One of the characteristics of this person's speech is that sometimes there is a long pause between two words. ”

"What does that mean?" Xiao Chen still looked at Lao Li puzzled.

Lao Li smiled and said, "When I look at you kid, I haven't experienced much, didn't you hear him cough twice at the end?" ”

"This ......"

If it weren't for Lao Li saying, Xiao Chen really wouldn't have noticed this.

Jiang Yu repeated the recording again, and this time, Xiao Chen finally noticed that in the last sentence of the dialogue, the murderer really coughed twice.

"However, I still don't understand...... Xiao Chen Zhanger was puzzled, "cough, what can it mean, there are more people coughing in China every year......"

You can't solve a case by coughing, right?

Lao Li shook his head helplessly and said, "If I hadn't been in contact with it, I might have been as confused as Xiao Chen." ”

Jiang Yu explained with a smile: "It seems that the requirements for the police are getting higher and higher, and they also need to know some medical skills." ”

"Uncle Li, Deputy County Magistrate Jiang, what are you talking about?" Xiao Chen was about to cut off his hair, but he still didn't understand what these two people were talking about?

Lao Li smiled: "Haha, if it weren't for the fact that there was an old Song next to me, maybe I wouldn't know what this cough and the pause in the middle mean?" Xiao Chen, do you remember when I told you that I have a professor friend? ”

Xiao Chen nodded: "Uncle Li, you're talking about that Professor Song, right?" ”

"That's right, Lao Song has chronic pharyngitis, and chronic pharyngitis has an obvious characteristic, that is, he feels phlegm in his pharynx, but he can't cough it out, and he can't swallow it," Jiang Yu said, "However, the human body has a protective mechanism, that is, when there is a foreign body in the throat, it will cough and discharge the foreign body to protect himself, even if he knows that there is no way to cough it out, but he will still subconsciously do this action." ”

Jiang Yu paused and continued: "In addition to coughing, there is another way, that is, to swallow the foreign body, although this method is a bit self-deceptive, but the self-protection mechanism will make people subconsciously make this action." ”

Speaking of this, his face became more serious: "This murderer should have a long-term history of chronic pharyngitis, during the call with Zhang Xianzhen's wife, whether he used a voice changer or not, the behavior brought by the disease has not changed, when he wants to hide his cough, he will subconsciously make swallowing movements, which is why he pauses in the middle." ”

Lao Li continued: "If the technology allows, maybe we can still swallow the sound of swallowing, Deputy County Magistrate Jiang, I'll go to the technicians now." ”

"Okay." After Jiang Yu finished speaking, he breathed a long sigh of relief, "Now that I can finally go back with peace of mind, you should rest early." ”

"Yes." The two of them stood up straight together, raised their hands, and looked at Jiang Yu solemnly.

Jiang Yu returned a salute before walking out of the Public Security Bureau slowly.

This night is destined to be a sleepless night.

Xiao Chen contacted the staff who had unblocked the sewer, but the other party refused to admit that the monitors had been installed in Zhang's house.

Lao Li immediately applied for an arrest warrant and arrested the person back.

Interrogation overnight.

"Uncle Li, the suspect's name is Ma Yong, his job has been to dredge the sewers, and he has not done any other work, he has no criminal record, and he is a good citizen."

"Good citizens lie?" Lao Li yawned, took out a thermos cup, put some wolfberries, and soaked a large glass of boiled water, before he said contentedly, "You interrogate first, I will squint for a while, and there is news to call me quickly." ”

Xiao Chen nodded hurriedly and walked into the interrogation room to interrogate the prisoner.

The suspect Ma Yong entered the police station for the first time, he was so frightened that he peed his pants, his legs trembled like chaff, and when he saw Xiao Chen coming in, he immediately shouted loudly: "Comrade policeman, I am wronged, I am wronged, I really don't know anything, I just go to the sewer." ”

Xiao Chen glanced at him: "What have you wronged, I haven't said anything." ”

Ma Yong suddenly looked at Xiao Chen with some embarrassment, and after a while, he said sneeringly: "I really didn't install a monitor in that house, and besides, I don't even know what a monitor is, how can I install a monitor?" ”

"Don't talk nonsense yet," Xiao Chen looked at Ma Yong and asked him, "Do you know Zhang Xianzhen?" ”

"I don't know, I don't know who it is." Ma Yong quickly denied it, for fear that if he was one step too late, he would suffer a big loss.

Xiao Chen smiled: "Don't be in a hurry to deny it, think about it, do you really not know him?" ”

"I really don't know," Ma Yong couldn't wait to take out all his hearts to show Xiao Chen, "Comrade policeman, I really didn't lie to you, I really don't know this person." Besides, how dare I lie to you? ”

He was going to be scared to death, how could he have the heart to deceive them?

Xiao Chen frowned slightly: "Then did you dredge the sewer for a family on the X of this month?" ”

"That day......" Ma Yong carefully recalled for a long time before he said: "It seems to be." ”

"Yes is yes, no is no, what do you mean?" Xiao Chen said in a somewhat bad tone.

Ma Yong was so frightened that he hurriedly said, "Yes, yes, then...... On that day, a family did call me and asked me to unclog the sewer for their house, if you don't believe me, you can check my mobile phone, there should be a record on the phone. ”

"You really didn't install a listener other than unclogging the sewers?" Xiao Chen said while looking through the records of his mobile phone.

"Comrade policeman, I'm just a drain dredger, and I don't know anything about these high-tech technologies, how can I install a monitor in someone else's house?" Ma Yong said, and suddenly said, "You said that I installed a monitor in someone else's house, I have to buy it to install it, without a monitor, how can I install it?" ”

"You don't have to worry about this," Xiao Chen looked at Ma Yong and said, "Other colleagues are already investigating, if it is found that you are lying, do you know what the consequences will be?" ”

"Of course I know, but I really didn't do it!" Ma Yong was about to cry, he had been diligent and diligent in his life, and he had never done anything illegal, but now he was going to be wronged, and he installed a monitor in someone else's house, and he really jumped into the Yellow River and couldn't wash it.

At this moment, there was a knock at the door of the interrogation room.

After a while, the door was pushed open, revealing Lao Li's kind face: "Xiao Chen, come out." ”

Xiao Chen glanced at Lao Li inexplicably, and after a while, he stood up and walked out.

As soon as he walked out, Xiao Chen immediately asked Lao Li: "Uncle Li, what's wrong?" ”

Lao Li glanced at the room, and after a while, he said gently: "We...... We may have caught the wrong person. ”

"Huh?" Xiao Chen was full of blood, and suddenly someone poured a basin of cold water on his head, and he suddenly shivered with cold, "How could it be?" ”

Zhang Xianzhen's wife said that only this person had been to their house during that time, and no one else had been there.

If this person hadn't installed a listener in Zhang's house, who else could have installed it?

You can't just put it on in thin air, can you?

Lao Li knew that it was the first time Xiao Chen had received such a big case, so he must have been in good spirits, holding the heart that he would inevitably solve the case, and a little sudden setback, and things that did not follow his development, would make him feel that the sky was falling apart.

He also came from a young age, so he can especially understand Xiao Chen's heart.

"Xiao Chen, don't worry," Lao Li took a sip of water before saying, "Listen to me slowly." ”