1995, Starting as a Criminal Investigation Expert

Whether or not the case can be solved before the deadline will not affect the technical team.

If a leader wants to scold someone, he can't scold the technical police officer.

Here we can borrow a phrase from Liu Weikun.

This is science. If there is evidence, then there is; if there is no evidence, then there is no evidence at all, and there's nothing we can do about it.

But Li Shu wanted to solve the case.

It's not just because of Han Jianjun's so-called "technical police are still police, and they need to solve cases."

The main reason is that this is the first case I've truly handled since becoming a police officer.

The first fingerprint I compared was that of these two suspects.

Who wouldn't want to get off to a great start in their career?

But everything is difficult at the beginning.

I thought that optimizing the methods would improve efficiency, but I only realized how difficult it was when I actually started working.

"You said you've already bought a system worth millions, so what's the difference between these two scanners?"

Li Shu stared at the scanner he was working on, muttering to Tan Guoxiong beside him.

This first step alone stalled the progress.

The entire system includes an optical fingerprint scanner for direct fingerprint acquisition.

Existing fingerprint cards can only be scanned and entered into the system using a scanner.

Liu Weikun said that this is a top-notch machine at present, but it takes nearly ten seconds to scan a fingerprint card.

Let's do a simple calculation.

If it scans five images per minute, that's 300 images per hour, and if it runs non-stop 24 hours a day, that's 7,200 images.

With a five-day deadline and over 60,000 fingerprint cards, it wasn't enough time to register them all.

Tan Guoxiong propped his head up with his hand and said, "That's really bad. It costs over 100,000 yuan a unit. That's not a scanner; it's a Santana."

A high-precision scanner, imported, not cheap.

Li Shu rested his chin on his hand.

If it weren't for this, Li Shu would have mentioned it to Han Jianjun long ago.

The crucial point is that everyone is waiting for the data to be entered, and the wait is agonizing.

The fingerprint cards were screened long ago. In the past two days, we used the method of human eyes and hands to compare the fingerprints of the motorcycle owners that were checked in the first 12 hours. We haven't done any other practical work.

All the physical evidence at the crime scene was examined, but nothing was found.

Ballistic analysis was also performed, but it was of limited help.

They did produce an expert report confirming that the gun in the September 5th case and the August 25th case (the fourth case) was the same gun, but that was all the work they did.

Seeing the special task force working so hard, Li Shuzhen became anxious and even considered going out to help with the investigation himself.

The two slept in the same room, and Tan Guoxiong knew what Li Shu was thinking.

Patting Li Shu on the shoulder, Tan Guoxiong said, "Li Shu, don't rush. You have to be patient. Like Instructor Cao said, the most important thing for us technicians is to be able to sit still."

After Cao Junfei returned, he had a long talk with Li Shu, as was his custom.

After a pause, Tan Guoxiong added quietly, "And sometimes, not all cases can be solved."

Li Shu was taken aback, but immediately understood what Cao Junfei was talking about.

It's his father's case, which remains unsolved to this day.

Reaching out and patting Tan Guoxiong on the shoulder, Li Shudao said, "Brother Yong is right, we must have hope."

As it stands, all we can say is that we've implemented this system and hope it can match fingerprints.

There's also the possibility that even with the system, the fingerprint still won't match.

So we really have to keep a little hope in mind.

Just then, Liu Weikun excitedly approached Li Shu: "Li Shu, I have some good news for you."

Li Shu jumped up and hurriedly asked him if the software was finished.

"No."

Liu Weikun shook his head. That's writing software, not something you can just write and finish.

Considering the urgency of the case, the team is already working overtime and staying up all night writing code.

But I really can't finish writing it in a short time.

"What other good news could there be?" Li Shu sat back down.

Liu Weikun said, "Isn't it because of the methods you proposed that we have been greatly inspired? Our boss has spoken up and discussed it with the company, so we're giving you this amount as a reward."

He shook his right hand.

"Five hundred?" Tan Guoxiong was taken aback.

"Hey!"

Liu Weikun, true to his Anjing roots, retorted, "That's all the courage you have. Think bigger."

Li Shu was taken aback and asked uncertainly, "Fifty thousand?"

If it's 50,000, that would be really good news.

That's enough to buy a house.

Liu Weikun's momentum faltered, and he said awkwardly, "It's not that much, five thousand is quite a lot."

Li Shu immediately lost interest: "You should hurry up and write your code."

Liu Weikun stuck his head over and complained, "Brother, you're in a hurry. I'm only 29 this year, look at the amount of hair I have."

As they were talking, Tan Guoxiong nudged Li Shu and winked at the clock hanging on the wall.

It's twelve o'clock now, all three needles in one go.

Li Shu's heart sank; the case was still unsolved within the five-day deadline.

That evening, my mother called to ask if the case had been solved yet.

She saw on the news that the police were offering a reward of 20,000 yuan for information leading to the arrest of the suspect.

Li Shu remained silent. If things had come to this point, even if they hadn't reached the end of their rope, they were close enough.

After hanging up the phone and returning to his dormitory, Li Shu sat back down and continued his previous work.

Li Shu is still trying to study this half fingerprint.

In addition to using the partition comparison method to extract feature points from incomplete fingerprints and delineate partitions, Li Shu also found another method in the system.

It's less of a method and more of an experience-based approach.

The term "incomplete fingerprint" has a definition in school textbooks.

Due to various complex factors such as the movement of the fingers, the shape and smoothness of the object's surface, different attachments on the fingers and the surface of the object, and the magnitude of the force exerted when forming fingerprints, incomplete, partially or mostly blurred, and deformed fingerprints are ultimately formed.

Faced with such fingerprints, some veterans who have worked in the field for a long time will try to deduce the complete fingerprint based on their accumulated experience.

For example, if the lines are blurry, he can look at the direction and trend of the adjacent lines, and then refer to the fact that the distance between the lines is the same, so he can infer the lines in the blurry area to a certain extent.

Furthermore, by using spatial imagination, one can predict what kind of deformation will occur on a curved surface due to different finger pressure.

Then adjust and restore the real fingerprint.

Li Shu is doing this job now: looking at the magnified, incomplete fingerprint under the light, studying the deformed areas, and then drawing it.

It may not be correct; it's all based on intuition.

But you can make multiple copies and compare them together later, which is like winning by sheer quantity. What if you're lucky and guess right?

Surprisingly, doing this can actually increase experience.

On the system side, the experience in fingerprint identification has increased to over a thousand.

On the sixth day after the crime, despite the reward offered and numerous phone calls received, the case still had not made any breakthroughs.

On the contrary, the reward brought many seemingly plausible but ultimately unsubstantiated clues.

You can't let this lead go; you have to verify and investigate it.

This actually increased the difficulty of the task force's work.

All the technical team could do was wait, wait for the fingerprints to be recorded, and wait for Liu Weikun to finish modifying the program.

It's impossible for everyone to focus entirely on this case.

In a city with a population of several million, cases keep happening.

Li Shu continued to study fingerprints and came up with a method to simulate the deformation caused by pressure using his own fingerprints, thereby accumulating experience.

By the seventh day after the incident, he had attempted to reconstruct five fingerprints that he felt might be accurate.

On that very day, Liu Weikun and his team completed the program modifications.

The program was updated around 2 PM that afternoon.

"The program is complete, but the fingerprint card registration isn't finished yet," Zhao Yong said, looking worried.

I know that the speed is already very fast. People like Pingyu next door spent more than half a month to complete the fingerprinting.

But it still feels slow.

It's been a week since the incident, and some people think the suspect may have fled to another place.

Liu Weikun shrugged and said, "Well, there's nothing I can do about it. To be honest, you guys are making pretty fast progress."

Of the more than 60,000 fingerprints, nearly 40,000 have already been recorded.

In another two or three days, the data entry should be completed.

At this moment, Li Shu suddenly said, "Captain Han, why don't we start the comparison now?"

Seeing everyone looking at him, Li Shu said, "We also have priorities when we're recording."

To avoid omissions, the conditions were relaxed.

For example, the age range is 20 to 40 years old.

But in reality, the suspect is definitely not that young or that old.

Therefore, when registering fingerprints, priority is given to those around thirty years old.

"Now that two-thirds of the fingerprints have been recorded, which means that the fingerprints that are likely to match have been recorded, I think we can start the comparison process," Li said.

Han Jianjun and Zhao Yong exchanged a glance, already understanding Li Shu's meaning.

"Captain Han, let's have a race then. I've been wanting to see just how fast this thing really is," Zhao Yong said.

Han Jianjun thought for a moment and nodded.

Li Shu turned around and went to get the fingerprint.

The original fingerprint, plus five fingerprints that I analyzed and deduced, made a total of six. I had Liu Weikun operate the system to directly input them into the system.

"Then I'll begin."

Liu Weikun turned to look at everyone, and after Han Jianjun nodded, he pressed enter.

The area has been defined, and the fingerprints have been processed. Li Shu couldn't help but feel a little nervous about whether it would work.

The computer hummed as it ran.

Soon after, the results were reported.

It is highly efficient; it can compare nearly 40,000 fingerprints in the blink of an eye.

Fingerprint number 1 returned 100 results.

It doesn't mean that the comparison was successful.

Instead, the system sorted the fingerprints from highest to lowest similarity and then provided the top 100 results.

Also, being ranked first doesn't mean it's highly similar. It's possible that the similarity is very low, but it's still the highest in the system's fingerprint database.

Therefore, manual verification is still required.

Everyone crowded around the computer screen to see the fingerprint that had the highest similarity.

It really does look a bit like it.

Liu Weikun's hands kept moving, constantly comparing the fingerprints with the other five.

Fingerprint number 2 is most similar to another fingerprint.

After all, this is an incomplete fingerprint, so it's normal to get different results.

At first glance, it does look like it, but whether it is or not remains to be confirmed.

Then it's number 3, and number 4.

When he got to number 4, looking at the fingerprint with the highest similarity, Li Shu suddenly had a strong intuition.

I feel like this is it.

These days, Li Shu studies this half of the fingerprint every day, and even dreams about it at night.

So now when I see this fingerprint that has the highest similarity, I have a strong intuition that it is it.