Detachment Commander's Office. Qin Yong was cross-legged, holding a small teapot, humming a pop song from thirty years ago.

Murder is not terrible, as long as you can solve the case, you are a good policeman. From the front-line criminal police to the present, Qin Yong has experienced thousands of cases, large and small.

There are almost a dozen or twenty homicides every year. It can be said that it was trained in the sea of corpses and blood.

In the face of the murder, Qin Yong already had a normal heart. When handling the case, it should be tense and nervous, and it should be overtime, and now, the case is solved, and it is time to relax.

In fact, it makes sense that being a police officer does not live long, and when the case comes, the adrenaline rushes, and it is common not to sleep for days and nights.

The case is over, and the whole person seems to be paralyzed. Qin Yong, who was leaning on the back of the chair, hummed a little song, squinted his eyes and was about to fall asleep.

I will go to the bureau tomorrow to report the case, and I can get off work at noon...... Buzz. The vibrating sound of the mobile phone woke up Qin Yong, who was just about to fall asleep.

"Lao Liu, are you busy over there?" The scene of the first crime is the most concerned part of all the homicide cases.

"It's almost busy here, but I've discovered a new situation."

"Oh? What's the situation? ”

Zhang Wei ...... Probably not the murderer! "Not a murderer? Liu Guodong's words were like an ice pick, straight into Qin Yong's heart.

The hazy drowsiness that I had just felt dissipated instantly. Jumping up from the chair, Qin Yong's voice was an octave higher: "What did you just say?" Liu Guodong's voice was low: "Zhang Wei, it is possible that he is not a murderer." Liu Guodong, who was far away in the No. 8 cold storage, was wrapped in a coat at the moment, and his frozen snot was flowing.

The work on the site is nearing completion and will soon be over. After collecting evidence from the scene, I can go back and sleep peacefully.

As a result, a phone call from Lu Chuan means that all work may have to start again.

"Did you find anything at the scene?" Qin Yong's first reaction was what evidence Liu Guodong found at the scene.

But Zhang Wei has already put it aside, and the criminal process he confessed is also very detailed, not like he is taking the blame for others.

"I didn't find anything here at the scene, it was Lu Chuan's side."

"He collected a dripping blood stain from the fragment of the corpse, the blood type did not match the blood type of the deceased, and guessed that it was left by the murderer."

"Before we caught Zhang Wei, Lu Chuan did a bloodstain analysis of the dripping blood type."

"But just now after Lu Chuan collected blood from Zhang Wei, he found that his blood type was type A blood, and the blood type dripping blood was type AB."

"Zhang Wei, it's very likely that he is not the murderer!" Hanging up the phone, Qin Yong put on his coat and went straight to the current laboratory.

When Liu Guodong called Qin Yong to report, Lu Chuan was processing the blood stains on the corpse to collect DNA information.

From a technical point of view, Lu Chuan only provided evidence of the current investigation. As for who the evidence points to, that's not what Lu Chuan is concerned about.

Therefore, after determining that Zhang Wei's blood type did not match the blood type of the dripping bloodstains, Lu Chuan's focus was on the extraction of bloodstain DNA information.

When Qin Yong came, the DNA information dripping with blood had just been extracted.

"Xiao Lu, Lao Liu said that there is a new discovery on your side?" Looking up and seeing that it was Qin Yong coming in, Lu Chuan nodded, and then continued to operate the computer.

Compared with the previous few months, Lu Chuan is no longer a newcomer who has to salute everyone he sees. The first-class meritorious service winner allowed Lu Chuan to accumulate enough status.

Now, no one talks about Lu Chuan's time when he joined the police. The entire criminal investigation detachment knows that Lu Chuan is an expert in fingerprint identification and analysis.

This is one of the most sought-after technical abilities. Maybe one day I have a fingerprint in my hand, and I need help.

"Team Qin, there is a discovery." Lu Chuan explained in detail the inconsistency of blood type comparison.

"According to Zhang Wei, he killed Wang Guizhi alone, and then drove a taxi alone to throw the body."

"In this case, it is impossible for Wang Guizhi's body to be stained with the blood of anyone except herself and Zhang Wei."

"And where did this drop of blood come from?" A drop of blood, insignificant, but sometimes, is enough to overturn the entire case.

When the police handle cases, what they pay attention to is not the coherence of logic. Logic makes sense, but reality doesn't necessarily make sense.

What happened in reality is not all logical. For example, Zhang Wei's motive for killing, according to his confession, the two killed people because they were arguing.

This is clearly illogical. But reality is that it can happen. Therefore, in the investigation and handling of any case, logical reasoning is basically an auxiliary analysis.

In the end, what you have to look at is evidence. Human and physical evidence should be complete, the chain of evidence should be complete, and there should be no contradictions.

According to Zhang Wei's account, the motive for the killing, the murder weapon, the crime scene, the process and method of throwing the corpse, etc., can all form a closed loop.

However, this drop of blood on the corpse made a loophole in the closed loop. Of course, Qin Yong knew what Lu Chuan meant.

The source of this drop of blood must be found.

"What about DNA information comparison?" Lu Chuan has just entered the information into the system and is comparing it. When Qin Yong asked, the result happened to come out.

"Huh?" Glancing at the report, Lu Chuan was slightly stunned: "The same source of information? ”

"What information comes from the same source?" Qin Yong saw the DNA comparison results come out and took a step forward.

"Oh," Lu Chuan clicked the mouse and printed the report: "When I collected Zhang Wei's blood, I also collected his hair and did a DNA information test. ”

"The bloodstains on Wang Guizhi's corpse show that it is of the same origin as Zhang Wei's DNA information, and there is a parent-child relationship between the two." Parent-child relationship?

"When Zhang Wei killed someone, his son was also there?" Qin Yong immediately understood what was going on.

"Even ...... Is it possible that it was not Zhang Wei who killed the killer at all, but his son? ”

Zhang Wei ...... Apothesizing for his son? Lu Chuan shook his head, these two conclusions cannot be distinguished by technology.

But now that you have this clue, it's not difficult to track it down. Zhang Wei said that he had been driving before the killing, and he would know by investigating the trajectory.

And according to the results of the previous investigation, Wang Guizhi took the bus home after work. Why did she get off the bus halfway to take a taxi, check it, and you can understand everything.

Taking the report, Qin Yong left the survey laboratory, and called on the phone as he walked: "Zhang Hui, re-interrogate Zhang Wei!" Lu Chuan packed up the instrument and the rest of the samples, put on his coat and left.

The on-site work on the side of No. 8 cold storage has not yet been completed, and Lu Chuan can still catch up with the finishing touches now. Interrogation room.

Faced with the DNA information comparison report in Zhang Hui's hand, Zhang Wei was speechless.

"Zhang Wei, did you kill the person?"

"Don't think that if you don't say anything, we can't help it."

"The person who sat in your car three nights ago, we are already looking for whether it was your car or your son's car that day, we will know as soon as we ask." At the same time as Zhang Wei's second trial, the arrest of Zhang Wei's son Zhang Xuanrong was also being carried out simultaneously.