National Forensic Doctor

Xu Taining came to the Criminal Police Detachment by bus. It felt very simple and there was no need to stop. He only had a pair of polished police trousers and a dusty jacket and walked slowly into the Criminal Police Detachment.

The new police officer standing guard at the door only looked at the ID and quickly saluted and let the person in.

These days, you really don’t dare to mess with a simple old man wearing a jacket.

Yu Wenshu opened a combat command room for Xu Taining in the detachment's conference room. Maps and topographic maps of Changyang City were hung on the wall. A white porcelain cup was placed on the table with green tea brewed in it, with a smile on his face. Prepare properly, and hide a little thought: if you save a little between your fingers, we can also have a prosperous New Year.

Xu Taining smiled back at Yu Wenshu, picked up the green tea, looked at the map, and said: "If you want to put a map, it's best to change it to a larger map."

"Uh, a large-scale map? This is already"

"I mean the map range." Xu Taining drew a circle in the air with his hand and said, "This is the map of Changyang City."

Yu Wenshu thought to himself, because we are the Changyang City Criminal Police Detachment.

Of course, he couldn't say that, but he still waited carefully and said: "We are considering that the murderer committed several crimes around the scenic spots in Changyang City."

"What you are thinking makes sense. It is indeed possible that the crime was committed around the scenic spots in Changyang City." Xu Taining nodded and added: "But it is also possible that the crime was committed around the scenic spots around Changyang City, or"

Xu Taining took out a laser pen from his old jacket, flashed a red light, and walked along the map and said: "It's also possible that it's around the ring road in Changyang City, or the ring expressway. ongoing."

Yu Wenshu's whole body was numb. Changyang City is the provincial capital, and the ring road around the city is 50 kilometers long. It will be expanded further. ． ． ． ． ． If this is an investigation, even if the criminal police detachment has plenty of funds, it can't help but spend it like this.

The political commissar was even more frightened when he heard this. He was afraid that Yu Wenshu would just agree to it, so he quickly said: "The entire ring road is monitored. There are high-definition cameras at the entrances to and from the elevated highway. In recent years, the murderer walked here. If it's a road, it's a trap for yourself."

"Maybe take a bus or take a taxi?" Xu Taining asked back.

The political commissar was stunned when he heard this. Indeed, the murderer only came out to kill people. There was no need to transport the body and dump it, nor to cut the body into pieces and bury it. He carried a nail gun with him. When he arrived at the chosen place, he didn't even have to choose it. He just found a place at random and got out of the car. You don’t need to drive yourself when you climb a mountain, kill people on the mountain, and go home after the killing. Public transportation makes it easier to hide traces.

"If we draw such a large area, the expenditure will be too high, and the bureau will not allow us to inspect the entire city." Yu Wenshu said cautiously.

"It's normal to have limited conditions. When I do investigation, the most common problem I encounter, the problem I encounter almost every time, is the limited conditions and funding restrictions." Xu Taining said naturally: "However, I raised this scope because I hope You can understand that it is impossible to cover everything. We must assume that the murderer is also subject to certain restrictions. If we do not make such assumptions, our funding will be problematic. But if the scope of the assumption is too small, our investigation may not be effective."

Yu Wenshu and the political commissar looked at each other and realized that Xu Taining was inoculating himself.

At the same time, the two of them felt their fear more deeply - Xu Taining was inoculating himself!

How much is this guy prepared to spend?

"Let's change this map." Xu Taining turned the laser pen in the air again.

"Okay. Then how big a map do you want?" Yu Wenshu's expectations were already very high.

Xu Taining shook his head at this time and said: "After you called me yesterday, I studied this case. I think that the investigation of the crime scene, or in other words, the investigation to find the path and method of the murderer entering the crime scene, etc. , are of little significance. The investment will be very large, but it may still slip through the net, which is a model that costs money and has poor results.”

Yu Wenshu was speechless as he thought of the area Xu Taining had just painted.

Indeed, the three cases occurred in three directions on the outskirts of Changyang City, and they were all parks with relatively good scenery, including hills and mountains. Citizens who went there for leisure included people living nearby and people passing through the city. Considering that the Ring Road is also far away from

Not too far away, even from nearby towns and villages,

Investigating the location and path of the murder is indeed a thankless task.

Furthermore, the murderer's three crimes were committed randomly, and the locations where they occurred may also be random. Although most human randomness is pseudo-random, using a relatively simple analysis method, for example, draw a circle with the three crime locations as the center, and the intersection of the three circles may be the murderer's residence or work scope. However, the actual case analysis cannot be so simple. There are too many preconditions for the delineation of this range. For example, it is assumed that the road conditions are uniform, the murderer does not change the means of transportation, and the murderer sets off in the same way every time. Location, assuming the murderer did not encounter any unexpected situations on the way

If, like foreigners, you only pursue a 50% homicide detection rate, this demarcation is not a big problem.

But it has reached the point of inviting Xu Taining, how dare Yu Wenshu draw such a circle.

Yu Wenshu looked at Xu Taining warily.

As the saying goes, a dog can't change its habit of eating shit, and Xu Taining's money-spending way of doing things couldn't be learned in a day. That's what the criminal police teams at all levels in Shannan Province have learned step by step.

If he says he spends a lot of money, he may really spend a lot of money, but if you say he will save money, you are just thinking blindly.

"You can check the surveillance video, but I don't think you should put too much hope in it. In the wilderness, the murderer only needs to wear a hat, an umbrella, and a hoodie, and all our work will be in vain." Xu Taining cut off again. A road.

Yu Wenshu nodded solemnly.

"In this case, I think it ultimately comes down to the weapon. Because the most special thing about this case is the weapon. A modified nail gun. Where did the nail gun come from? Where was it modified? Who modified it? These three I think as long as one problem is solved, the case can be solved." Xu Taining used his fingers to break down the case into pieces and make it clear and clear.

Yu Wenshu's face showed hope unconsciously.

Xu Taining's analysis is indeed much more meaningful than finding evidence at a crime scene.

Xu Taining took a sip of tea and said slowly: "There are many people who have the ability to modify nail guns, but in fact there are not many. My estimate is that there are tens of thousands of people in Changyang City and surrounding areas."

Yu Wenshu was stunned: "Tens of thousands of people?"

Xu Taining: "Those who are engaged in the machinery industry and those who are electricians are all possible."

"Wait a minute." The political commissar said, "Even if we come to him, how can we prove that he has modified a nail gun?"

"The three crimes were committed in the morning. Two were working days and one was a day off. The three times were very far apart. His alibi must be incomplete. Screen the list and look at it again. Is there any way to further screen?" Xu Taining answered quickly.

Yu Wenshu knew that Xu Taining's working mode was like this. When in doubt, he would first screen the list. If the number of people screened out was small, he would ask specific questions, use real-person polygraph testing, or conduct secret investigations. When there are too many people screened out, we will screen in another direction and conduct cross comparisons. After narrowing down the list, we will go back to the first step.

Speaking of which, Xu Taining's method of solving crimes is also very stupid. It is different from Jiang Yuan's stupid method, and it is more expensive.

Yu Wenshu missed Jiang Yuan for a moment, and then took a deep breath: "Do it. Do as you say."

There was no room for him to hesitate and waste time on this case.

Afternoon.

While Xu Taining was still preparing, a reporter from Changyang Evening News came to the Criminal Police Detachment.

The reporter was called by the director. The attitude was very good, very professional and serious. He asked a lot of questions, and some of them seemed to have been prepared by professionals.

Yu Wenshu answered obediently. He is now the detachment leader of the provincial capital, so the reporters here are reporters.

For the captain, what comes is probably a fruit plate, which means the same thing: the case is solved, you eat the fruit, it’s sweet, and the reporter will write a report for you. If the case cannot be solved, there may not be a report, but the report will definitely be sent.

Yu Wenshu was not only secretly glad that he had invited Xu Taining. In this way, even if he died, he would die without regrets.

At the same time, Jiang Yuan was also seizing the time to look at the nails.

The murderer in this case has already killed three people, and although the time between the two murders is variable, you can't expect a serial killer to stick to a certain schedule. Especially this kind of random killing without conflict of interest shows that he does not follow social order.

Do not agree with the existing social moral norms.

Therefore, the murderer could start killing the fourth person at any time. Completing the long nail comparison as soon as possible is the best breakthrough Jiang Yuan has seen so far.

After being nurtured, participated in and solved so many cases, Jiang Yuan has gradually formed his own understanding of criminal investigation.

In his opinion, the murderer in this case must have planned, imagined and designed for a long time before committing the crime. This kind of serial killer is fundamentally different from ordinary people killing people.

Ordinary people kill people. On the one hand, they are restricted by interests, which have fetters and grips. On the other hand, ordinary people usually start planning and implementing murders when their interests are greatly damaged. Moreover, planning does not necessarily lead to execution. Usually, it is necessary for interests to continue to be damaged, or a certain trigger point occurs. , he implemented it.

In this way, when ordinary people kill people, they are involved in interests, time constraints, and not to mention emotional impulses. All of the above make them restricted in the matter of killing, making it difficult for them to reach the limit of intelligence and physical strength. Peak state.

Serial killers are different. The core of serial killers is antisocial factors. In psychological terms, they have no ability to empathize. When ordinary people are very young, such as two or three-year-old children, they will cruelly kill ants, insects and other weak creatures without hesitation, but as they grow older, they do so less and less. , which is the growth of empathy and the result of social education.

Serial killers are not like this. They have lost their ability to empathize for various reasons. Therefore, their attitude towards humans is similar to that of young children towards ants. Of course, their intelligence is normal, so they can also understand the requirements of social morality and where the boundaries of the law are.

In order to evade punishment and satisfy their inner needs, serial killers often plan to kill people from a very young age and hold back the execution until they reach adulthood. They have already trained themselves.

Facing such criminals, it is definitely not possible to use ordinary methods to deal with them.

At this time, it was the police who thought of it. They had probably thought of a high-end serial killer with one finger. Those weak and small ones had been screened out when they committed the first crime.

When Jiang Yuan saw the long nails, he could even imagine the murderer's pride.

The killer could have used steel balls, but he instead used ordinary spikes, which are harder to track, and modified a nail gun specifically for this purpose. This shows that he knows very well that the "bullets" fired from the nail gun are his biggest flaw. He can take away the bullet casings and the nail gun, and pay attention to the footprints and fingerprints, but it is impossible for him to pick out the bullets or long nails on the spot. , which may leave greater hidden dangers.

However, based on Jiang Yuan's work these two days, he felt that the murderer's time in the world was getting shorter and shorter.

If at the beginning, Jiang Yuan was worried about not being able to find suitable spikes, over the past few days, Jiang Yuan's confidence has increased.

In Jiang Yuan's view, comparing long nails and comparing fingerprints actually have something in common.

What fingerprint comparison pursues is actually not exactly the same. Mark the feature points, sort them according to the number and similarity of the feature points, and then find the closest ones among the candidate fingerprints, and eliminate fingerprints with obvious similarities.

The long nail ratio is actually a characteristic point.

Just choose those locations that are easy to leave traces and compare them constantly.

Now, with more than half of the nails in hand, Jiang Yuan can eliminate them directly. Many of the reasons for elimination are not even

Use your eyes to see it, and you can spread it out with just a push of the weight.

This also made his progress greatly advance.

Who would have thought that LV6's tool mark inspection would actually have room for improvement due to self-training.

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