Chapter 442 Nails

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 the enemy of sharp weapons.

In fact, blunt weapons are similar, some are good and some are bad, the main reason is that they are afraid that they will not be killed in one hit, and the risk increases sharply. 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 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 bullet. Now, it doesn't leave the shell, only the nails, and it's not a special nail, 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 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 spikes 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 probably 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 local police officers. Wan Baoming shook his head slowly and said, "The suspect was found based on the description of a couple who went mountain climbing. It's just that the time was close to the second case, and the evidence was incomplete. Now that the third case has appeared, his suspicion is very small."

"Has the suspect been in jail?"

"Yes, he was in jail for violent debt collection. When he came out, all the P2Ps died and he was unemployed. I thought he was taking revenge on society."

Jiang Yuan had never seen anyone before, so he didn't say much and asked to see the body again.

The ultimate eyewitness of a murder case is always the body. Jiang Yuan is a forensic doctor. He left the body for the last, hoping to accumulate some information first, so that he could be more targeted.

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

After the two left, the technical police officers in the Criminal Science Center couldn't help but talk about it.

"Ningtai Jiang Yuanha looks like he is also feeling at a loss." "He is a forensic doctor. Now that he has seen the body, he may find a direction."

"I heard that he went to Luyang City this time and solved the case of burying the body on the highway. He arrested three people in one go. Miaohe County was also flattened by him, and the detention center was full."

"Otherwise, can Yu Zhi 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 cannot be solved, it will be annoying. Everyone should not sleep. Wait for the murderer to come out and commit crimes for the fourth time."

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

The atmosphere in China is different from that in foreign countries. When foreign police chiefs encounter cases such as serial killers, they can swallow their anger as long as they can bear the scolding. But if uncontrollable serial cases occur in China and cause the anger of the leaders, anything can happen.

Even the technicians of the Criminal Science Center have to worry about themselves under the thunderstorm.

No time to sleep, in this case, it may just be the beginning.

Everyone was silent for a while.

Changyang City Criminal Science and Technology Center, in fact, was built by Shannan Province at a huge cost. After all, it is the main force of the criminal science in the provincial capital city, whether it is capital allocation or recruiting and retaining people, it actually has advantages.

In recent years, the performance of Changyang City Criminal Science Center has not been bad, it depends on who it is compared with.

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

Moreover, unlike other industries, there is a tacit understanding of you and me.

There is almost no tacit understanding between criminal police and criminals. Criminals have too much to pay, and they can't cooperate with criminal police unless there is chaos.

For two consecutive days, Jiang Yuan buried himself in the quagmire of evidence. The forensic autopsy did not yield any useful information, but it did clarify the causes and consequences of some of the three elderly people's illnesses. Obviously, it is a little too late to know these things now.

The nails purchased online were delivered one after another, and they were piled up in packages. Soon, the office assigned to Jiang Yuan was crowded, and everyone began to pile nails in the warehouse.

No one knew whether this would produce any results, including Jiang Yuan himself.

The only difference was that other technicians thought this was a big project, but only Jiang Yuan felt 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 made records, one marked the classification and was responsible for recording, and Jiang Yuan sat on the table himself, first looking at the original evidence nails again and again, and even put them under the horseshoe mirror to look at them, and then looked at the bought nails one by one.

Ordinary people can tell whether two nails are produced in the same factory at a glance. The simplest example is color. Some are yellow, some are silver, and some are gray. In addition, there will be slight differences in specific shapes and sizes.

Because of tolerance, nails of the same size of 3*12 will also have different thicknesses when compared.

However, these can only screen out a part of the nails. There are always some nails with very similar colors, shapes and sizes, which are almost indistinguishable with the naked eye.

According to the ideas of other technicians, if these nails want to be distinguished again, they have to be checked by instruments. Moreover, it is easier to prove than to prove. Even if a certain instrument proves that two nails have the same elements, it is still difficult to prove that they come from the same source. There are always more complex instruments waiting there.

However, Jiang Yuan does not seem to be bothered by this.

He sits in front of an empty desk, picks up the long nails to be checked on the left, and hands them out on the right. Even if a comparison is completed, the whole process is not only efficient, but also very quiet.

It was not until Wang Chuanxing started to move the long spikes to the warehouse that the technicians of the Criminal Science Center realized that Jiang Yuan was not joking, but had really mastered a skill that they did not quite understand.

"Are you really competing with long spikes? Can you compare?" Wan Baoming received the news and hurried over. Looking at the temporary assembly line in Jiang Yuan's office, he was speechless.

"Currently, we have found three candidates. We will know the final result after we finish 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 evidence you did? Can you determine the source of the propellant?"

"It's confirmed, but it's useless." Wan Baoming sighed. "What do you mean?"

"According to the trace element test, there is a small amount of aluminum powder and gum arabic in the residue of the propellant. There are only three companies in China that produce propellants. The propellant used by the murderer happened to come from Nanshan Company, which has the largest sales volume. They changed the process in 1986 and have produced 1.4 billion nail bullets annually. We can't investigate further."

Jiang Yuan nodded as if he knew this, and then continued to concentrate on the nails.