National Forensic Doctor

Changyang Criminal Investigation Center.

Independent small building, green office environment, suitable temperature

A group of people surrounded Jiang Yuan and the evidence "long nails" with serious expressions.

This is the most favorable evidence they have obtained so far. Just like the bullets in a shooting, the spikes in this case carry all the expectations of everyone.

Otherwise, the evidence in the case is weak circumstantial evidence. Any surveillance video, extracted fingerprints, footprints, or some cigarette butts, blood stains and other objects found at the scene are all self-comfort products and cannot point to the murderer.

Jiang Yuan thought from the murderer's perspective and felt that long-range weapons really brought a lot of advantages. If you are also killing someone, your bare hands can easily be injured by the victim, leaving clues behind. The knife is slightly better, but as a melee weapon, it is also easy to be re-injured. Skills such as blood stain analysis are even more powerful enemies of sharp weapons.

Blunt weapons are actually similar, some are good and some are bad. The main reason is that you are afraid that you will not be killed in one hit, and the risk increases dramatically. In addition, the lack of deterrence of blunt weapons will greatly increase the chance of the victim resisting.

The modified nail gun has obvious advantages as a long-range weapon. Not only is it less likely to cause resistance, but the key is that it kills people very quickly and leaves very little traces of physical evidence.

The disadvantage is that it leaves physical evidence, such as the spike in front of you.

Wan Baoming also introduced the situation and said: "This nail should not be a special model for nail guns. The murderer changed it to a nail gun, and the change was very strange. The most common nail gun nowadays fires metal steel balls, with a range and power It will all be bigger. If he does this, he can only shoot up to two meters, but it is still quite powerful."

"There are currently three common types of nail guns, pneumatic, electromagnetic and gunpowder. The gunpowder type is the most common, also called a cannon nail gun. Originally it is equivalent to adding a blank bullet behind the nail, which is similar to the blank bullet of the weapon type. It’s similar, it’s called a nail bomb. Now, there is no shell left, only the nails, not special nails, which is very troublesome.

"As for the shooting residue, physical and chemical analysis and infrared spectroscopic examination have been carried out. Trace physical evidence is being processed, but there is no news yet."

Jiang Yuan just nodded. To be honest, he had never seen a nail gun or nail bomb before, but from the perspective of tool marks, they were all the same. And the main reason why he dared to come over and sell it when he saw it was a random murder was LV6's skills and tool mark inspection.

As the saying goes, the passing geese leave traces, let alone such a large industrial product.

"The nails are indeed ordinary models, but there is still a way to trace their origins." Jiang Yuan had already considered this issue when he came here, and asked: "Can I buy the same long nails sold in the market and compare them? "

"There are so many types and manufacturers. There are more small factories that produce nails than there are manufacturers that produce steel balls." Wan Baoming was a little surprised and said: "It is better to wait for the results of the trace physical evidence of the nail bullets to come out and chase the nail bullets." Walk?"

"The murderer has changed all the nails. It is probably difficult to find out the source of the nail bombs. However, he can walk on two legs. Let's check them all." Jiang Yuan did not force it. His plan was indeed more troublesome, but , for a case of this level, it is normal for two clues to be investigated at the same time.

Moreover, seeing how carefully the murderer committed the crime, with such obvious loopholes in nail bullets, it is not easy to trace the whereabouts of the murderer.

"I'm trying to figure out how to buy all the long nails of the same style sold on the market." Wan Baoming felt that if the source of this thing could be found, it would be a clue. However, ordinary long nails are too common.

Jiang Yuan added: "You can buy the same long nails from every store online and compare them. You can also buy all the long nails of the same style sold in the market in Changyang City and compare them."

Wan Baoming didn't expect Jiang Yuan to come up with such a stupid idea, and couldn't help but said: "How long will it take to compare? The key is, can it be compared?"

"Okay. It won't take long. As long as you buy enough nails, you can always find them."

For Jiang Yuan, when he got the nails and put them together, it was just a matter of whether they were made by the same company.

Eye matter.

Wanbaoming simply couldn't understand how strong LV6's tool mark identification was. He still frowned and said: "Even if the nails are from the same company,

It may also be produced by different factories, and the same factory may also have different batches.”

"Try to buy as much as possible. If you start buying now, the possibility of buying the same batch is relatively high." Jiang Yuan doesn't care whether it is the same batch, but if a factory has different production lines,

"Okay." Wan Baoming could only agree.

"That's all the clues in front of us, let's give it a try." Jiang Yuan didn't give any guarantee. He thought of a possible breakthrough path, but it didn't mean that he was 100% responsible for this path.

Wanbaoming naturally understood. After confirming the decision, he first arranged for people to go to various platforms and markets to buy nails. Although when I think about it, I always feel that it is impossible to buy all the same long nails on the market, but if I think about it carefully, the murderer most likely did not expect that the police would make a breakthrough in this aspect. At least he could not produce his own long nails.

If he uses steel balls - if he uses steel balls, there will naturally be a supply channel for the steel balls. I'm not sure which channel is easier to investigate.

"At least it's a clue." Wan Baoming put down his phone, smiled with Jiang Yuan, and said, "It's better than the busy work we have been doing these days."

"Where is the suspect? Could he be the criminal?" Jiang Yuan couldn't see this from the file because they were all uncertain.

All the people present were his own police officers. Wan Baoming slowly shook his head and said: "The suspect was found based on the description of a mountaineering couple, but it was close to the second case in time, and the witnesses and physical evidence were not complete. Now. Now When the third case came up, his suspicion was very low.”

"Has the suspect been in jail?"

"Well, I used to engage in violent debt collection, but when I came out of P2P, all the people died, and I lost my job. I thought he was taking revenge on society."

Jiang Yuan had never seen anyone, so he said nothing and asked to see the body.

The ultimate witness in a murder case is always the corpse. Jiang Yuan, a forensic doctor, left the corpse at the end in the hope of accumulating some information first so that he could be more targeted.

Wan Baoming was already prepared and immediately took Jiang Yuan to the anatomy room.

After the two people left, the technical policemen at the Criminal Investigation Center couldn't help but talk about it.

"Ningtai Jiang Yuanha looks like he also feels numb." "I am a forensic doctor. Now that I have seen the body, I might be able to find the direction."

"I heard that he went to Luyang City this time and solved the case of burying corpses on the highway. He picked out three people in one go. Miaohe County also let him go and the detention center was full."

"Otherwise, Yu Zhi can help Ningtai County apply for a laboratory? There are only a few places in the province. However, this case is really difficult to solve."

"If it can't be broken, it will cause trouble. Don't sleep, everyone, wait until the murderer comes out to commit crimes for the fourth time."

Several brigades of the Changyang City Criminal Police Detachment are actually on tight guard now. Even if the case cannot be solved in a short period of time, it should not happen again for the fourth or fifth time.

The atmosphere at home is different from that abroad. When foreign police chiefs encounter cases such as serial killers, they can do it as long as they can endure the scolding. But if a series of uncontrollable cases occur in the country and arouse the anger of the leaders, then anything can happen.

Even the technicians at the Criminal Investigation Center have to worry about themselves under the thunderstorm.

No time for sleep, in cases like this, might just be the beginning.

Everyone was silent for a while.

Changyang Criminal Science and Technology Center was built by Shannan Province at a huge cost. After all, it is the main force of the criminal department in the provincial capital city. It actually has advantages in terms of capital allocation and recruitment and retention.

Over the years, the Changyang Criminal Investigation Center has performed well, depending on who it compares to.

However, this time, everyone hopes that Jiang Yuan can live up to his name. This is also a special feature of the police profession. It is okay to be jealous, but someone must be able to handle the business.

Moreover, unlike other industries, there is a tacit understanding that you are good to me and everyone is good to each other. Detectives and criminals

It is almost impossible to have any tacit understanding between them. Criminals have to pay too much, and they won't be able to cooperate with the criminal police until chaos breaks out.

For two days in a row, Jiang Yuan buried himself in the quagmire of evidence. The forensic autopsy did not yield any useful information, but it did clarify the origins of some of the illnesses of the three old men. Obviously, it is somewhat too late to know this now.

On the contrary, the nails purchased online were delivered one after another, and they were piled up in packages. Soon, the office assigned to Jiang Yuan could no longer move, and everyone began to pile nails into the warehouse.

No one knows whether there will be any results if this is done, including Jiang Yuan himself.

The only difference is that other technicians think this is a big project, but Jiang Yuan feels relaxed.

There was no need to choose an auspicious day. Seeing that there were more nails bought, Jiang Yuan first called Mu Zhiyang, and then Wang Chuanxing and Tang Jia. The four of them sat in the office, two of them marked the unpacking and took notes, and one The person marked the categories and was responsible for the video recording. Jiang Yuan sat on the table and looked at the original evidence nails again and again, and then put them under the horse hoof mirror to look at them. Then, he took the purchased nails one by one. Look over.

Ordinary people can tell whether two nails are produced by the same factory at first glance. The simplest example is the color, some are yellow, some are silver, and some are gray. In addition, the specific shape and size will also be slightly different.

Due to tolerances, nails of the same 3*12 size will have different thicknesses in comparison.

However, these can only filter out a portion of the nails. There are always nails that are so similar in color, shape and size that they are almost indistinguishable with the naked eye.

According to the assumptions of other technicians, if these nails are to be distinguished again, they must be inspected with instruments. Moreover, it is easy to prove but not difficult to prove. Even if it is proved on a certain instrument that a certain element of two nails is the same, it is still difficult to prove that they come from the same source. There are always more and more complex instruments waiting out there.

However, Jiang Yuan didn't seem to be bothered by this.

He sat in front of an empty desk. He picked up the long nails to be inspected on his left side and passed the long nails out on his right side. Even if he had completed a comparison, the whole process was not only efficient, but also very quiet.

It wasn't until Wang Chuanxing started to move the spikes in the warehouse that the technicians at the Criminal Science Center realized that Jiang Yuan was not joking, but had really mastered a skill that they didn't quite understand.

"Are you really competing on long nails? Can you compete?" Wan Baoming received the news and came in a hurry. Looking at the temporary assembly line operation site in Jiang Yuan's office, he was a little speechless.

"We have found three candidates so far. We will know the final result after reading all the rest." Jiang Yuan did not need to explain anything else to Wan Baoming, and then asked: "What are the results of the trace physical evidence you did? Can you determine the source of the propellant? ?"

"Sure, but it's of no use." Wan Baoming sighed. "How to say?"

"Trace element testing showed that there was a small amount of aluminum powder and gum arabic in the residue of the propellant. There are only three domestic companies producing propellant. The propellant used by the murderer happened to come from Nanshan Company, which has the largest sales volume. They changed the technology in 1986 and now their annual output is 1.4 billion rounds of nail bullets, so they can no longer be investigated."

Jiang Yuan nodded as he had known this before, and then continued to work on the nails.

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