1995, Starting as a Criminal Investigation Expert

As dusk settles, the city lights begin to twinkle.

Xu Qiang strolled over to the technical team.

Upon entering, I was suddenly taken aback.

On one side of the large office, Li Shu stood in front of the blackboard, holding chalk, pointing at the blackboard and talking animatedly.

I listened to a few words.

It seems to be about alignment issues.

The system can automatically find an optimal rotation and translation method based on the overall flow of the ridges to perfectly align the feature points of the two fingerprints.

Then Han Jianjun and his group of eight or nine people gathered around the blackboard, listening intently.

Some people even had their laptops spread out on their laps, swiping away notes.

"Goodness, what are you guys doing? Is Xiao Li giving you... a lesson?" Xu Qiang walked over and patted Zhao Yong, who was standing on the outside.

Zhao Yong turned around and greeted them, then quickly said, "It was Li Shu who introduced the working principle of the AFIS system to us."

After saying that, he glanced at Li Shu, pursed his lips, and said incredulously, "You're really young, you know a lot about computers. Look at us, to be honest, I only know how to turn a computer on, and I'm afraid of breaking it."

How does the AFIS system work?

Upon hearing this, Xu Qiang immediately perked up and looked up at the blackboard.

I recognize all the individual characters, but I don't quite understand them when they're put together.

Moreover, there are not only words, but also pictures, including a coordinate system, which makes it even more incomprehensible.

I've never scored above 70 in math since I was a child.

Zhao Yong turned to Xu Qiang and asked what had come over.

"No rush."

Xu Qiang waved his hand.

He came here because of the case in the High-tech Zone.

Fingerprint matching is out of the question.

The existing clues have almost reached a dead end.

And today is September 1st.

It's been almost a week since the last case on the 25th.

Xu Qiang had thought about it himself.

The suspect either killed someone and is now on the run out of fear.

Either they're temporarily lying low, waiting for something big to happen.

He prefers the latter.

The suspect didn't steal much money, but he ended up with a life.

With two suspects, each only gets 10,000 yuan, yet they end up with a life. How can they not feel cheated?

Xu Qiang's intuition, honed from years of handling cases, told him that the suspect was holding back his pregnancy.

Moreover, once it takes action, it will definitely be a major case.

Originally, it was just a burglary, but now that he's killed someone and cut off his escape route, he has no choice but to do something big, make all the money he could in his life, and then run away.

Feeling uneasy, Xu Qiang could only think of another way.

He came over to discuss with Han Jianjun again, to see if they could dig out some more clues from the physical evidence at the scene.

For example, soil was extracted from the suspect's footprints.

There was also oil stains; oil stains were extracted from some drawers and safes. Perhaps we could analyze the composition in more detail and make some discoveries.

At this moment, Li Shu summarized in front of the blackboard: "Captain Han, that's what I mean."

"The AFIS system has an inherent disadvantage in comparing incomplete fingerprints, so by using this partitioned comparison method, the system can only compare local feature points, thereby helping us to complete a wide range of screening."

"Of course, to achieve this, the program needs to be optimized. To be honest, I don't understand computers, so I'll have to ask the manufacturer if they can implement this kind of local comparison function."

When the AFIS system performs an auto-comparison, it compares the feature codes.

Two fingerprint codes mark the fingerprint's characteristic points, orientation, and other information.

To make a comparison, you need to find a positioning anchor point first.

The system will establish a coordinate system with the top left corner as (0, 0), and then put the fingerprint into it to form a coordinate point.

Then, through algorithms, the fingerprint coordinates are rotated, translated, and scaled to find the maximum degree of overlap.

However, this process involves comparing the entire fingerprint.

Faced with an incomplete fingerprint, the system is unaware that it is only comparing a portion of it, thus becoming confused and unable to complete the comparison.

The so-called partition comparison method tells the system that I am only comparing a part of the fingerprint, not the whole fingerprint.

Therefore, further optimizations and adjustments are needed in the program to make the system understand this.

This is a problem that only the manufacturer can solve; Li Shu himself doesn't have that ability.

The crowd remained silent, each appearing deep in thought.

Han Jianjun crossed his arms, his eyebrows furrowed in thought.

Li Shu explained it very clearly and directly, and even this old guy understood it.

His intuition told him that Li Shu's so-called partitioning comparison method was feasible.

It's a simple principle: you can compare the whole, but you can't compare the parts.

But the key issue is not the method, but rather that there must first be such a system.

Li Shu also brought up this point, and asked sincerely, "Captain Han, can't we implement an AFIS system?"

Without this system, we can only use manual input.

Even with a locator, the efficiency wouldn't be very high, since it's a partial comparison of incomplete fingerprints.

Each adjustment requires a comparison, which is too time-consuming.

Han Jianjun hugged his arms tightly, lost in thought and remained silent.

At this moment, Guo Xiangyang suddenly spoke up, saying, "Old Han, Li Shu is right. This thing will have to be installed sooner or later. You should talk to Director Tang about it. If all else fails, since the imported ones are too expensive, we can just install a domestic one first."

"You know Lao Hu from Peng'an, right? I'm very familiar with him. He mentioned to me that the domestic system they installed at the beginning of the year only cost a little over one million."

Han Jianjun glared at him.

Judging from your tone, it sounds like it's only worth a hundred or so yuan.

That's ten thousand.

Looking up and seeing Li Shu still staring at him expectantly, Han Jianjun said helplessly, "Li Shu, your method is excellent. It's remarkable that you could come up with such a method and understand the AFIS system so well."

Li Shu himself said that he often bought professional journals at school and learned about the AFIS system through various channels.

Such a motivated child deserves praise.

"As for whether or not to log into the system, that's a big deal. I'll think about it some more. It's getting late, everyone should go home now."

Han Jianjun told everyone to leave work.

Li Shu knew this was no small matter, and it wasn't something a trainee police officer like himself could decide.

Anyway, he's already explained the method; now it's up to Han Jianjun to put in the effort.

The day the call came, Li Shu knew that he also wanted to implement an AFIS system.

Upon seeing Xu Qiang, Li Shu stepped forward and greeted him.

"Not bad, that's good."

Xu Qiang patted Li Shu with a smile, without saying anything more.

Li Shu called Tan Guoxiong, who was still a bit dazed, and they packed their things to get ready to leave work.

Han Jianjun also saw Xu Qiang. He first saw Guo Xiangyang out, then returned and waved to Xu Qiang before going into his office.

Upon entering the office, Han Jianjun didn't offer to pour water; he simply sat down in a chair.

Xu Qiang had to do it himself.

Just as he poured the drink, Han Jianjun jumped up and said, "Old Xu, come with me to find Director Tang."

He thought about it.

The most important reason why the bureau has never adopted the AFIS system is definitely money.

This is not a small amount of money.

The bureau is poor, but there are many places where money is needed.

Another reason is that Director Tang and his colleagues believe that even if the system is purchased, no one will know how to use it, or will use it poorly.

This is also why Han Jianjun was so eager to recruit that undergraduate student.

But their hopes were dashed; the man was detained by the provincial authorities.

But things are different now.

We need people who understand AFIS systems, and Li Shu is one of them.

They've already offered optimization suggestions, what more do you expect?

With people, the basic conditions for accessing the system are met.

Moreover, Han Jianjun came up with another reason.

Li Shu proposed the so-called partition comparison method, which is specifically designed for incomplete fingerprints.

This isn't targeting any one specific case, but all similar cases.

Previously, there wasn't a very good solution when encountering incomplete fingerprints.

If this method is used in the system now, it will solve the problem of comparing incomplete fingerprints, which is equivalent to improving the technical capabilities of the technical team.

They always talk about innovation, urging us to focus on science and technology to improve our case-handling skills.

Now that the solution is right in front of us, it wouldn't be appropriate not to support it.

Before Xu Qiang could speak, Han Jianjun dragged him out of the office.