1995, Starting as a Criminal Investigation Expert

Wu Liqun's home is in the southern part of Dangshan County, near the provincial border, in a place called Lilou Town.

His purchasing station was located on the northwest outskirts of the town, near the county road leading to the county seat. It was less than 100 meters from the fork in the road off the county road to his purchasing station.

And in such a town, there must be places that sell coal.

There are three businesses in total. Two of them mainly sell coal briquettes, while only one, located in the southeast of the town, sells raw coal.

Xiao County, located east of Dangshan, produces coal and is under the jurisdiction of Huaibei Mining Bureau.

Tian Jiepeng continued, "Director Li, I'm at the coal station right now. Captain Gu led a team to investigate the area. I saw it; the coal station is a large compound, and the four-wheeled vehicles that haul goods pass by the gate. The ground around the gate is almost completely black, covered in coal slag."

"That's possible. The suspect may have passed by here and stepped on coal dust. We searched the area around the crime scene and didn't find any houses with coal piled up on the road."

It mainly burns coal briquettes.

Moreover, even if you buy raw coal, you'll usually store it at home, not on the road.

Based on that analysis, it's highly likely that the suspect left it when passing by the coal station.

After a moment's thought, Li Shu said, "Visiting them is probably useless."

It's such a small town, and a month has passed since the incident. Gu Yanfei and his team have probably questioned everyone in the town by now.

There was a video recording in the yard. Although it wasn't very clear, it gave us a general idea of ​​the two people's clothing and basic information. Also, a witness was later found who knew that the suspect had a round face and protruding ears.

In this situation, since the initial visits yielded no results, asking again now will obviously not yield any results either.

Whether it would be useful or not, Tian Jiepeng did not make a judgment, but simply said, "Director Li, I have some ideas. I want to take the extracted raw coal back for analysis to see what kind of coal it is."

"Think about it, there are so many types of coal, both smokeless and smokeless, and the quality of coal from large mines is different from that from small mines."

"I just asked the person in charge of the coal station, and all the coal they sell comes from Zhuxianzhuang in Xiaoxian County. It is mainly coking coal, with one-third coking coal and some gas coal."

"Then can we use volatile matter and sulfur content to determine if it is coal sold by this coal station?"

"If the suspect stepped on coal and it was still at the scene, it must have been stepped on a few hours before the incident and then brought to the scene."

"If it's not this coal station, then that says a lot. For example, the suspect went to another place before committing the crime, or he came from somewhere else to commit the crime."

"Then they must have means of transportation that allow them to travel long distances."

"Furthermore, if we can identify the type of raw coal, can we also roughly pinpoint where it came from based on the coal's sales region?"

Coal can be classified into many types based on volatile matter, caking properties, and sulfur content. However, the properties of coal production are stable over a period of time, which makes it possible to differentiate between them.

Li Shu nodded in realization; he hadn't expected this.

As an expert in the province, Tian Jiepeng has a wealth of experience.

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"Director Tian, ​​you're right, this approach is sound, I think we can do it."

After chatting for a while and asking about the fingerprints and NA, Li Shu hung up the phone.

In fact, methods like this—finding substances in mud from shoe prints, determining their composition, and then reconstructing the tracks—fall into the field of trace physicochemical analysis.

Based on the system data, it is possible to achieve even greater depth in the future.

For example, by measuring soil composition, as well as plant and pollen, environmental measurements can help determine where the soil came into contact with the soil.

Later that day, Tian Jiepeng made another phone call.

Some latent fingerprints were indeed found through fumigation and were extracted, but they were mostly incomplete and blurry, and we are still trying to compare them.

He reasoned that the suspect was unlikely to have taken off his gloves.

The fact that no bloody fingerprints were found is enough to show that the suspect was very cautious.

Regarding the biological samples, we did find some hairs in some nooks and crannies, but we can only distinguish their lengths at this point, and we cannot determine which hair was left by the suspect.

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The plan is to send all the samples to the two institutes and try to perform NA typing.

It's also very difficult.

Because hair itself is made of keratin, only the hair follicle contains NA.

The white spots at the ends of naturally shed hairs, which resemble hair follicles, are not actually complete hair follicles. They are keratin protein concretions from the hair root sheath, containing only a very small number of trace cells.

If stored for a long time, it will degrade significantly, making it difficult to complete the typing.

Later in the phone call, Tian Jiepeng also mentioned the coal mine.

He arranged for someone to inquire about it.

Dangshan is located at the intersection of four provinces, so it has a significant source of coal for civilian sales.

The first two are Xiaoxian County in the east and Suixian County in the south, which mainly produce one-third coking coal and gas coal.

Then there's the area in eastern Shandong, which also produces coal, about one-third coking coal and mainly gas coal, but it's farther away and not as convenient as Xiaoxian.

The old mine in Jiawang, Ningjiang, has entered a period of decline. Its output is very low, and it is far away, so it hardly sells to this area.

Then there's the Central Plains region, where Dangshan borders Ningbo.

Ningbo also has coal mines. Last year, the Xinzhuang Coal Mine went into operation, producing a large amount of high-quality anthracite.

However, anthracite coal is expensive and not widely used by the general public.

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However, there have always been a large number of small coal mines in the northern part of Ningbo, which mainly produce cheap lean coal, which is much cheaper.

These three types of coal are relatively easy to distinguish.

Therefore, Tian Jiepeng sent the samples back to the provincial capital overnight for scientific testing to determine what kind of coal it was.

The results came out a day later.

It's neither anthracite nor one-third coking coal; it's lean coal.

One-third of the coking coal and one-third of the gas coal are relatively light and have lower hardness, making them more prone to breakage.

Lean coal, on the other hand, has a high density and hardness, making it even harder.

From this perspective, it is easier to preserve the fragments, forming small pieces that, with each step, embed themselves into the tread pattern of the shoe and are subsequently brought to the crime scene.

This result also confirmed one thing: the place where the suspect stepped on the coal was not the coal station in Lilou Town.

On the phone, Tian Jiepeng's tone was still enthusiastic. He said, "Director Li, I've discussed it with Captain Gu. We'll take Lilou Town as the center and expand outwards, visiting every coal sales point to see which area is selling low-grade coal from Ningbo. We'll then use the coal to find the right people."

Of course, the suspect may not necessarily have stepped on the coal outside the coal station; it's possible that he bought lean coal somewhere, piled it up there, and the suspect stepped on it.

Even the poorest coal doesn't necessarily come from Ningbo.

There are many possibilities.

However, coal stations are easier to investigate. In addition, if we have some information about the suspects, we can ask them questions and maybe we can find something.

"Okay, I'll do the typing as soon as I receive the sample. Let's contact each other immediately if there are any issues." Li Shu hung up the phone.

The fingerprints have been compared, but no match was found; all the fingerprints collected belong to the victim.

The fingerprint method is now blocked.

Another day later, the samples collected from the crime scene were delivered.

There were 27 hairs of varying lengths, along with blood samples from five victims.

Inside the NA laboratory.

Li Shu and Ni Jingsong chatted together while watching Ye Lin and the others do NA typing.

"To be honest, these magnetic beads are much more convenient," Ni Jingsong said with a smile.

Although the NA automatic extractor is not yet complete, the magnetic beads are ready, which does not prevent Ni Jingsong and his team from using it in their daily work.

You don't need a magnetic rod; you can simply use a magnet to attach it to the bottom of the test tube and then remove the supernatant.

Compared to traditional phenolphthalein, chelating resin, and magnetic bead methods, the advantages are astonishing.

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It is non-toxic, easy to operate, and most importantly, it has a good purification effect, thorough adsorption, and minimal template loss.

Li Shu smiled and said, "It's a new technology. Once the equipment over there is ready, it will only be easier to operate."

It's fully automated. For clean samples like this, you just need to pre-process them, put them in, and then you don't have to worry about them anymore.

Ni Jingsong nodded in agreement and then brought up the matter of the research.

Li Shu has already sent Zhang Yanbei and the others out to Yunnan, Guangdong, Songpu, and other domestic companies and research institutes in the field of genetics and biology.

Chen Yan, on the other hand, also collected a large amount of foreign journal materials according to her own requirements.

"I won't ask for specifics, what do you think of the conditions?" Ni Jingsong asked.

Starting from scratch to catch up with others, he managed to complete in one fell swoop what others had taken decades to accomplish; his speed was truly astonishing.

Li Shu shook his head slightly: "Not very optimistic."

Without investigation, it's surprising to learn that not only has China not started industrial research on key consumables for typing like tap enzymes, but in the specific research and development field, all the consumables used are imported from abroad.

Basically, we don't do any research. At most, we might conduct some research and exploration on the application of other people's reagents.

"Honestly, I feel like these importers from Huamei are making a killing."

This investigation made Li Shu realize the severity of the situation and strengthened his resolve to develop his own products to replace imports.

The foreign exchange we painstakingly earn domestically is quickly taken back by others through various channels before we can even enjoy it.

"And there are devices like electrophoresis apparatus, but I can't even ask them. I have no idea how they do it. I'm thinking of taking one apart and reverse engineering it, but I don't have the money."

Equipment worth millions can't just be dismantled like that.

Ni Jingsong sighed softly, and was about to say something when the results for the sample over here came out.

Of the 27 hairs, only 6 were successfully amplified.

In other words, the remaining 21 hairs either have insufficient cell content or have already degraded.

This is also related to the fact that the site was indoors, the temperature was low, it was winter, and the dry conditions provided relatively better preservation.

If it's moved outdoors, it will degrade almost completely in a week, let alone a month.

"At least there are still six roots left," Li Shu said.

Before I started, I was really prepared that I wouldn't be able to get a single amplification.

Ni Jingsong nodded in agreement, feeling that the creation of the Six Roots was also related to technique.

The purification effect of magnetic bead adsorption is better than that of previous technologies.

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But after hesitating for a moment, Ni Jingsong added, "However, let's not be too happy yet. Think about it, we don't know when these hairs fell out. People come and go in the house, relatives, neighbors, and even farmers who come to sell cotton. They may have left hair in the house."

Li Shu was certainly aware of this, but he couldn't think that far ahead at the moment, so he urged Ye Lin and the others to continue with the typing.

I worked overtime until late at night, and the results came out one after another.

The five strands of hair matched up: one from Wu Liqun, one from his father, and one from his young son.

There was only one hair, which did not match any of the five victims.

For Li Shu, this was definitely an exciting result; perhaps this hair belonged to the suspect.

Especially the second suspect, who had a physical altercation with Wu Liqun, and it's possible that some of his hair fell out during the fight.

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