Chapter 416: Nail

Changyang City Criminal Science Center.

Independent small building, lush office environment, suitable temperature...

A group of people surrounded Jiang Yuan with serious expressions, as well as the evidence "long nail."

This is the most favorable evidence they have obtained so far. Just like the bullet in a shooting case, the long nail in this case carries everyone's expectations.

Apart from this, the evidence for the case is weak circumstantial evidence. Things like surveillance videos, extracted fingerprints, footprints, or some cigarette butts, bloodstains, etc., found at the scene, all belong to self-comfort items and cannot point to the murderer.

Jiang Yuan stood from the murderer's perspective and felt that long-range weapons really brought great advantages. Killing with bare hands is easy to be injured by the victim, thus leaving clues. Knives are slightly better, but as a melee weapon, they are also easily counter-injured, and skills like bloodstain analysis are the nemesis of sharp weapons.

Blunt weapons are about the same, with pros and cons, mainly because they are afraid of not being able to kill with one blow, and the risk increases sharply. In addition, the deterrent power of blunt weapons is insufficient, which will also greatly increase the chance of the victim's resistance.

The modified nail gun, as a long-range weapon, has obvious advantages. Not only does it not easily lead to resistance, but the key is that it kills very quickly, leaving very few traces and physical evidence.

The disadvantage is that it left physical evidence, such as the long nail in front of him.

Wan Wan Baoming also introduced the situation: "This nail should not be a model specifically for nail guns. The murderer modified the nail gun very strangely. The most common modified nail gun now fires metal steel balls, and the range and power will be greater. He did this, and it can only shoot two meters at most, but the power is still quite large."

"There are three common types of nail guns: pneumatic, electromagnetic, and gunpowder. Gunpowder types are the most common, also called cannon nail guns. It is equivalent to adding a blank cartridge behind the nail, similar to the blank cartridge of a weapon model, called a nail cartridge. Now, no shell was left, only the nail was left, and it is not a special nail. This is very troublesome..."

"In terms of shooting residue, physical and chemical analysis and infrared spectroscopy have been done, and micro-trace evidence is being done, and there is no news yet."

Jiang Yuan just nodded as he listened. To be honest, he had never seen any cannon nail guns or nail cartridges before, but from the perspective of tool marks, they were all the same. And he ran over to sell his services because he relied on Level 6 skills, tool mark inspection.

As the saying goes, a wild goose leaves a trace, not to mention such a large industrial product...

"The nail is indeed a common model, but there are still ways to trace it." Jiang Yuan had considered this problem when he came, and added: "Can we buy the same long nails sold on the market for comparison?"

"There are too many types and manufacturers. Small factories that produce nails are more numerous than manufacturers that produce steel balls." Wan Wan Baoming was a little surprised: "Why not wait for the results of the micro-trace evidence of the nail cartridge and follow the nail cartridge?"

"This murderer even modified the nails. It is estimated that the source of the nail cartridges is very difficult to check. However, walking on two legs, let's check both lines." Jiang Yuan didn't force it. His plan was indeed more troublesome, but for a case of this level, it was normal to check two clues at the same time.

Moreover, seeing the murderer committing crimes so carefully, it is really not easy to trace the murderer through such obvious loopholes as nail cartridges.

"The same long nails sold on the market... I'll think of a way to see how to buy them all." Wan Wan Baoming felt that if this thing could find the source, it would be a clue. It's just that ordinary long nails are too common.

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

Wan Wan Baoming didn't expect Jiang Yuan to propose such a stupid method, so he said: "How long will this take to compare? The key is, can it be compared?"

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

For Jiang Yuan, once the nails are in hand, putting two nails together and seeing if they are produced by the same factory is just a matter of looking at them twice.

Wan Wan Baoming couldn't understand how strong Level 6 tool mark identification was, still frowned, and said: "Even if they are nails from the same family, they may be produced by different factories, and the same factory has different batches..."

"Try to buy them all. If you start buying now, the possibility of buying the same batch should be relatively high." Jiang Yuan didn't care whether it was the same batch, but if a factory has different production lines...

"Alright." Wan Wan Baoming could only agree.

"There are only so many clues in front of us, let's try." Jiang Yuan didn't make a guarantee. He thought of a possible path, which didn't mean he had to be 100% responsible for this path.

Wan Wan Baoming naturally understood. After confirming, he first arranged for people to buy nails on various platforms and markets. Although thinking about it, he felt it was impossible to buy all the same long nails on the market, but after thinking carefully, the murderer probably wouldn't think that the police would break through from this aspect. He at least couldn't produce long nails himself.

If he used steel balls—using steel balls naturally has steel ball supply channels, and it is hard to say which channel is easier to investigate.

"At least it's a clue." Wan Wan Baoming put down his phone and smiled at Jiang Yuan: "Better than us being busy blindly these past few days."

"The suspect, could it be the perpetrator?" Jiang Yuan couldn't see these from the file because they were all uncertain things.

Everyone present was their own police officer. Wan Wan Baoming shook his head slowly: "The suspect was found based on the description of a couple hiking. It was just close to the time of the second case, and the witnesses and physical evidence were incomplete. Now that the third case has appeared, his suspicion is very small."

"Has the suspect been to prison?"

"Yes, he went in for violent debt collection before. After coming out, P2P all died, so he lost his job. I thought he was retaliating against society."

Jiang Yuan hadn't seen the person, so he didn't say much, and proposed to see the corpse again.

The ultimate eyewitness of a homicide case is always the corpse. Jiang Yuan, as a forensic doctor, left the corpse to the end, hoping to accumulate some information first, so that he could aim at the target.

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

After the two left, the technical police officers of the Criminal Science Center couldn't help but discuss.

"Jiang Yuan from Ningtai... looks like he also feels numb." "He is a forensic doctor. Now that he has gone to see the corpse, maybe he will find a direction."

"I heard that he ran to Luyang City this time and solved the case of burying the corpse by the highway, pulling out three people in one breath, and Miaohhe County was also leveled by him, and the detention center was filled up."

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

"If it can't be solved, it will be annoying. Everyone won't sleep, waiting for the murderer to come out and commit a crime for the fourth time."

Several brigades of the Changyang City Criminal Police Detachment are now strictly guarding. Even if the case cannot be solved in a short time, don't let the fourth or fifth time happen again.

The atmosphere in China is different from that abroad. Police chiefs abroad who encounter serial killers can just endure the scolding. But if an uncontrollable serial case occurs in China, causing the leaders to be furious, then anything can happen.

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

No time to sleep, in such a case, may just be the beginning.

Everyone was silent for a while.

The Changyang City Criminal Science and Technology Center, speaking of which, was also built by Shan Nan Province with huge funds. After all, it is the main force of the provincial capital city's criminal science. Whether it is capital allocation or recruiting and retaining people, it actually has advantages.

Over the years, the Changyang City Criminal Science Center has performed well, it just depends on who you compare it with.

However, this time, everyone hoped that Jiang Yuan could live up to his name. This is also the special nature of the police profession. Jealousy and talent can be, but business must be carried by someone.

Moreover, unlike other industries, there is still a tacit understanding that you are good and I am good. There is almost no tacit understanding between criminal police and criminals. Criminals need to pay too much, and they won't cooperate with criminal police until the chaos is rampant.

For two consecutive days, Jiang Yuan buried himself in the quagmire of evidence. The forensic autopsy didn't get any useful information, but it clarified the ins and outs of some illnesses of the three old men. Obviously, knowing this now is a bit late.

The nails bought online were delivered one after another, piled up in bags. Soon, the office assigned to Jiang Yuan couldn't be walked on, and everyone started piling nails in the warehouse.

No one knew whether doing this would have results, including Jiang Yuan himself.

The only difference is that other technicians think this is a big project, only Jiang Yuan thinks it is easy.

There is no need to choose any auspicious day. Seeing that there are more nails bought, Jiang Yuan first called Mu Mu Zhiyang, then called Wang Wang Chuanxing and Tang Jia. Four people sat in the office, two people marked and unpacked and made records, one person marked and classified and was responsible for recording, and Jiang Yuan sat on the table himself, first looking at the original evidence long nail again and again, and even putting it under the horseshoe mirror to look, and then, he looked at the nails bought one by one.

Two nails, whether they are produced by the same factory, look at them roughly, ordinary people can also distinguish some. The simplest, for example, color, some are yellow, some are silver, some are gray... Besides, the specific appearance and size will also have slight differences.

Because of the tolerance, the same 6.3*12 size nails will also have differences in thickness when compared.

However, these can only filter out part of the nails. There are always some nails whose color, appearance, and size are extremely similar, almost indistinguishable to the naked eye.

According to the assumptions of other technicians, if this part of the nails wants to distinguish the differences, they have to be checked by instruments. Moreover, it is easy to prove existence but difficult to prove non-existence. Even if it is proved on a certain instrument that the elements of two nails are the same, it is still very difficult to prove that their sources are the same. There are always more and more complex instruments waiting there.

However, Jiang Yuan doesn't seem to be troubled by this.

He sat at a cleared desk, the long nails to be checked on the left, and the long nails handed out on the right, which was considered to have completed a comparison. The whole process was not only efficient but also very quiet.

Until Wang Wang Chuanxing started to go to the warehouse to move the long nails, the technicians of the Criminal Science Center realized that Jiang Yuan was not joking, but really mastered a skill they didn't quite understand.

"Are you really comparing long nails? Can you compare them?" Wan Wan Baoming received the news and came in a hurry, looking at the temporary assembly line operation field in Jiang Yuan's office, and was speechless.

"Currently found three candidates, and I will know the final result after seeing the rest." Jiang Yuan didn't need to explain anything else to Wan Wan Baoming, and then asked: "How is the result of your micro-trace evidence? Can you determine the source of the propellant?"

"Determined, but it's useless." Wan Wan Baoming sighed. "How to say?"

"Micro-element detection, there is a small amount of aluminum powder in the residue of the propellant, and there is gum arabic. Domestic propellant is produced by three companies in total. The propellant used by the murderer happens to come from the Nanshan Company, which has the largest sales volume. Their process changed in 1986 until now, with an annual output of 1.4 billion nail cartridges, so it can't be checked."

Jiang Yuan nodded as expected, and then continued to bury his head in comparing nails. ===== CHAPTER 417 =====

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

"Trace element analysis shows that the propellant residue contains a small amount of aluminum powder and gum arabic. There are only three companies in the country producing propellant, and the propellant the killer used happens to come from Nanshan Company, which has the highest sales volume. Since they changed their manufacturing process in '86, they've produced 1.4 billion nail gun cartridges to date. We can't investigate any further."

Jiang Yuan nodded, having long expected this, and then continued to bury himself in comparing the nails.