1995, Starting as a Criminal Investigation Expert

The room was cramped, so the group didn't go inside but stood in the hallway.

"Old Xu, what's he looking at?"

Zhang Shenghua, the leader of the 803 Three Musketeers and the current head of the Criminal Investigation Corps, asked in a low voice.

He made the decision to ask Li Shu for help in studying the half fingerprint.

So when Li Shu finished reading the case file and asked to go back to the scene, he made a special effort to take the time to accompany him.

When the case occurred, he was the one who investigated it with his master, Duan Chengyan, so he was extremely familiar with the entire case.

Xu Qiang, clutching his briefcase, stared at Li Shu.

Li Shu had been standing on the stool, staring at the vent for almost ten minutes.

"You're using your brain, aren't you?" Xu Qiang said after thinking for a moment.

I've heard that geniuses, when they start thinking, become completely absorbed and focused, without any distractions.

Li Shu's reaction was like...

"Should we ask?" Chen Shengkang asked in a low voice from behind.

If you have any thoughts, feel free to share them. Or if you have any requests, such as recreating the scene, you can also mention them.

Chen Shenghua shook his head and said, "Forget it, don't bother him."

No sooner had he finished speaking than Li Shu made a move.

I simply picked up a pen and started writing and drawing in my notebook.

He wrote for a while, then stopped, still standing there, staring intently at the ventilation opening.

August 10, 1981, was a sweltering summer day.

A six-story residential building in the city.

This building is quite old. Underneath the residential building, there is an air-raid shelter that was built in the 1970s.

By the 1980s, this air-raid shelter had been converted into a hotel.

That afternoon, some guests reported a foul smell in the corridor. After searching, the staff found that the smell was coming from room 42.

After knocking on the door without getting a response, I used my key to open it.

Room 42 is only ten square meters in size and is a three-person room.

Staff found someone sleeping in bed and couldn't wake them up. They then remembered that this person had been sleeping in the same position the past two days when they came to clean the room.

Upon closer inspection, it became clear that something was wrong; there was blood at the corner of the mouth, and the person was already dead.

Call the police immediately.

The deceased was 28 years old and a purchasing agent from a prosthetic rubber parts factory in Shandong Province. According to the forensic examination, he died two days earlier, on the 8th, the night he checked into the hotel.

The victim had as many as seven electric shock marks on different parts of his face, and was determined to have died from electric shock shock.

The person had been dead for two days, but the hotel staff hadn't noticed and were still cleaning the room every day.

Therefore, the entire crime scene was essentially deliberately destroyed, and no useful physical evidence was found.

But since this person was electrocuted, electricity must be used.

The entire room was converted from an air-raid shelter, and there were no electrical outlets inside.

Only the single fluorescent tube at the top has an exposed wiring connection, providing access to electricity.

The fluorescent light is hung at the entrance of the room, and above the door is the ventilation duct of the air-raid shelter.

The material is common sheet metal, and the surface is painted with a light beige color that matches the wall color.

The air vents are louvered grille panels, and fingerprints are collected on the panel outside the vents.

The grille in front of us is not the one from the crime scene back then.

The one from the crime scene has been removed and sealed in the evidence room.

This was installed in the hotel; it's the same style.

After committing the crime, the suspect hid the tools used in the crime inside the ventilation duct.

The four fingerprints left outside the grille are from the right middle finger, left thumb, index finger, and ring finger.

In other words, the suspect opened the air vents with both hands.

Of all the fingerprints, the clearest is the one on the right middle finger.

After discovering the fingerprints, they found the electrical wire used in the crime inside the ventilation duct. It had been modified by the perpetrator, who had soldered a red women's headband onto it to act as a conductive medium.

Then, using the victim's delivery slip, they wrapped a 21-centimeter-long watermelon knife.

Unfortunately, no fingerprints were found on the wire headband or the knife.

The knife has a plastic handle that is rough and textured, making it unsuitable for extraction.

Back in 81, people didn't even have ID cards; registration and check-in relied entirely on letters of introduction.

My roommate was a man named Li Yiqing, who checked in with a letter of introduction from a traditional Chinese medicine hospital.

On the 9th, this person did not check out and secretly left.

Later investigation revealed that the letter of introduction was fake; there was no such hospital, and it was forged by the suspect himself.

However, this guy stayed at the hotel for a few days, and quite a few people saw him, so there is a composite sketch in the file.

But it was no use; we didn't know the person's true identity.

Then, 16 days later, a similar case of robbery by electrocution occurred in a city in Binh Chau province.

This time, the victim was lucky; he was woken up by the electric shock.

During the resistance, the suspect became frightened and jumped into the river to escape.

Then in September, two more robbery cases involving electric shocks occurred in two cities in Jangsi Province, resulting in the deaths of two people.

After the fourth case, the suspect disappeared without a trace for 14 years.

Li Shu closed his notebook and jumped to the ground.

The reason I came to the scene again was to simulate the posture in which the suspect exerted force at that time.

What kind of pressure will the fingers endure during the entire exertion process?

Once you have a clear idea of ​​what's going on, it will be very helpful to deduce the direction of the lines and find key features from the blurry fingerprint.

"Chief Chen, were only four fingerprints detected back then?" Li Shu asked.

I believed Chen Shengkang and his team wouldn't make such a basic mistake, but I still asked anyway.

Li Shu was mainly considering that during the process of removing the buckle, he wouldn't leave fingerprints on only four of his ten fingers.

Chen Shengkang hurriedly entered the room and pointed to the wind vents above to explain the situation.

This room was converted from an air-raid shelter; it's only about two meters high, and you can reach it with your hand outstretched.

Just as Li Shu had expected, there were traces of fingers on the inside of the grille and even the inside of the pipe.

However, unlike the panel, which doesn't collect dust and has a smooth surface, it has the potential to leave fingerprints.

After explaining the situation, Chen Shengkang asked, "Li Shu, what are your plans next?"

Li Shu looked around the room and said, "I'd better take a look and try it out first."

Just like in the Qiao Suqing case, the old method was used: try to deduce the direction of the fingerprint lines from the blurry fingerprints.

Or, to put it another way, use a microscope to look for tertiary feature points.

When comparing back, Liu Zhenping's topological theory can also be used.

Using just one finger for comparison might lead to mistakes.

However, if all four fingers have distinctive features and they all match, then it can definitely help in identifying the identity.

Upon returning to 803, Li Shu immediately began studying the fingerprints at the scene.

I also went to the evidence room and carefully examined all the physical evidence collected from the four crime scenes.

In the latter three cases, the suspects clearly improved; they gained experience and left behind even less physical evidence.

Songpu is a large city and is at the provincial level, so the physical evidence is very well preserved.

Sealed and protected from light.

This is a good thing.

What Li Shu needs to do now is not only to study the four fingerprints, but also to find clues from the 19 pieces of physical evidence from the four cases.

They had all been in contact with the suspect, which may have left some traces.

For example, when the suspect opened the air vent panel, he grabbed the inside of the grille and pried it outwards with force.

The grille itself is a narrow strip, and it's covered in dust, so it's impossible to brush it with powder to extract a complete fingerprint.

But Li Shu doesn't need a complete fingerprint; just one trace might be enough to help him pinpoint one or two key features.

Then, by piecing together all the features like a jigsaw puzzle, we might be able to achieve a breakthrough.

pity.

Li Shu spent two days working in Songpu, but progress was not smooth.

On this day, looking at the grid panel in the evidence bag in front of him, Li Shu suddenly had an idea: could he extract fingerprints from this thing again?