1995, Starting as a Criminal Investigation Expert

Wei Ranhui went outside and played a digitally captured video on his computer.

Chen Yan followed behind Li Shu, peeking out curiously.

Judging from the angle, the camera should be under the eaves, facing a courtyard.

Then it was still nighttime, and there was only light on the right side of the screen.

This should be the direction of the main room door, and then a light was turned on.

Wei Ranhui said, "Today is December 5th, right? This is a case that happened on the 13th of last month in Dangshan County, Su'an City, Anhui Province."

"Look, this is a cotton purchasing station in Su'an, in northern Wanyang. Cotton is usually harvested in October, and the peak season for cotton purchasing is in early November."

"The large volume of cash transactions is probably why criminals targeted this purchasing station."

As the introduction was being presented, the camera focused on the courtyard wall in the upper right corner.

The house faces south, and the camera is under the eaves, to the left of the main room door, diagonally facing the entire courtyard. Therefore, the wall that the criminals climbed over belongs to the east wall of the courtyard.

The two suspects skillfully scaled the wall and then crept along the base of the wall toward the entrance of the main room.

Wei Ranhui pointed at the screen and said, "Look, these two guys. The camera caught them. Neither of them was wearing a mask. But when they first climbed into the yard, they were in the dark. The light bulb on the main room door was always on, but it was a low wattage, only 15 watts, so it couldn't illuminate them clearly."

"Then, you see, when these two people came into the main room, after the lighting conditions improved, they happened to enter a blind spot of the camera. We looked at it frame by frame, and even in the best frame, it was like this."

He pulled up a frame of the image.

It's the frame before the two people disappear from the camera's view.

The person in front happened to be looking down, while the person behind was probably turning their head to look in the direction of the courtyard, so only half of their face was captured in the photo.

The fact that a cotton purchasing station proactively installed CCTV shows that the owner is security conscious and knows that he handles a lot of money at this stage, so he takes precautions.

But closed-circuit television equipment is expensive, so I doubt they'll install such a high-quality one.

Li Shu could guess this just by looking at the black and white image and seeing the severe ghosting.

Therefore, this frame of the image is not clear. It is viewed from above and is very blurry. On the screen, there is only half of the face, about the size of a fingernail. If you zoom in, it becomes a jumble of colors.

This is the entrance screen, and also the exit screen.

The two returned the way they came, climbed over the wall and left, clearly carrying a small backpack.

He was facing away from the camera, so his face wasn't even captured in the shot.

The invalid segments in the middle of the video were removed. Li Shu asked around and learned that the complete video was 24 and a half minutes long.

That's the time of the crime.

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Ordinary closed-circuit television, without a generator (character overlay device) to timestamp the video, cannot accurately determine the time of the crime.

Based on the forensic examination, we can infer that the crime occurred around 1 a.m.

Li Shu went back to look again and asked, "How much money was stolen? Did anyone die?"

When they climbed in, the two men were clearly wearing gloves and clutching pistols.

Wei Ranhui sighed and said, "This is the busiest time of year. The victim's parents came from the countryside to help, and with their 6-year-old son, all five of them are dead."

Chen Yan gasped softly from behind.

Li Shu's expression immediately turned serious. Annihilation of an entire family.

"Was it a simple murder to cover it up, or did the victim resist and the robbery escalate?" Li Shu asked.

The two men weren't wearing hoods and were carrying guns, so they might have come with the intention of leaving no survivors.

But generally not. Robbery and murder are completely different concepts. Unless someone is a heartless and ruthless beast like Zou Gang who enjoys killing, most people will leave themselves a way out.

Wei Ranhui said, "It seems to be a resistance. As for how much money was stolen, judging from the account book, it's estimated to be around 20,000 to 30,000, which is not a small amount."

Li Shu remained silent.

That's probably because they have too much money and can't bear to part with it, which is why they rebelled.

Wei Ranhui continued, "The people in Su'an have been investigating for a long time but haven't found anything. That's why they've turned their attention to this videotape and sent it to us. Let's see if we can think of a solution."

Nowadays, few police stations install CCTV cameras when handling cases. Even if they do, the recordings are often unclear and have limited value. They usually only resort to CCTV footage as a last resort.

"Li Shu, can you help me think of a way to deal with this?" Wei Ranhui asked.

Li Shu crossed his arms and played the video over and over again.

I think it's unlikely.

After a long pause, Li Shucai shook his head and said, "Take image processing as an example. We use Wiener filtering and constrained least squares. These methods only enhance the image, remove noise, make the picture cleaner, and sharpen the edges. In short, they make the image more expressive."

"But if we want to break through the information volume barrier, perform super-resolution reconstruction, restore unknown information, and make the unclear information clear, this requires a complex degradation model, which we cannot do."

Wei Ranhui should have known these words, but Li Shu was still saying them to Chen Yan behind him.

"The multi-frame super-resolution reconstruction I just mentioned can be used for video, but the current recording hardware is not up to par. It's only one frame per second, so as I said, it's almost unusable. We can only wait for the hardware to develop."

"However, if frame skipping is treated as a single image, it is still not feasible due to the limitations of the hardware."

There are actually ways to do it.

Image processing has always been a widely applied research field.

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It has a wide range of uses, including in astronomy, geography, military medicine, and more.

So image algorithms are constantly being iterated. According to system data, the concept of artificial intelligence, as seen in science fiction movies, has even emerged in the future, using artificial intelligence to calculate and enhance images.

These methods are too far-fetched and completely unnecessary.

More recent methods, such as bilateral filtering and TV noise reduction, might improve the picture quality.

However, the same problem remains: the image is more expressive, but the information that was not captured clearly in the first place cannot be restored.

The foundation for achieving image restoration is continuous displacement, using models to construct the image.

Moreover, even if we were to develop our own algorithm now, we would first need to find a math expert to discretize the mathematical formula.

That's easy, I know people, like Geng Zheng.

Then, we use languages ​​like [language name] to complete the compilation, gain a deeper understanding of the algorithm, and solve the program's problems.

Wei Ranhui and his team can also do this step.

But even after the program is written, it still needs to be adjusted and adapted to different recording devices and recording formats.

Finally, after extensive testing, simulation, and verification, the program can be optimized.

This whole process can take several months to complete.

Li Shu could work with Wei Ranhui to get the TV denoising and other algorithms working, but for the current case, it was clearly too late to use them.

The available methods are either to start from other directions, such as fingerprints or NA, or to try to reconstruct the suspect's appearance from the video footage, as used in the Yu-Chou case.

But this video recording, though it looks long, over twenty minutes, only shows the suspect being exposed to the camera for a few seconds.

In the Yuzhou case, the suspect was in front of the camera for five minutes, which is 300 frames.

Furthermore, the case in question occurred at night, with a 15-watt light bulb constantly burning, resulting in extremely poor lighting conditions.

In the Yuzhou case, it wasn't dark yet, and the jewelry store was brightly lit, making the scene bright and the changes in light and shadow relatively clear.

The difficulty is on a completely different level.

Li Shu pulled out a chair and sat down, instructing, "Chen Yan, go get me a drawing board and pencils."

Chen Yan hurriedly left.

Wei Ranhui frowned and said, "What, we still have to use the old method?"

Li Shu nodded, explained the difficulties, and said, "I can only say I'll give it a try. Here, give me the contact information for the Su'an Municipal Public Security Bureau, and I'll ask them later."

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This is a family annihilation case; five lives were lost.

Then it was another gang crime, with both of them carrying guns. Once they committed this crime, it was impossible for them to stop.

Many criminals, after committing murder by accident, understand that once they are caught, they will face certain death. In such cases, their crimes often escalate without any restraint.

Therefore, these criminals must be caught as soon as possible; otherwise, it is highly likely that they will be part of a series of serious crimes.

Wei Ranhui nodded and said, "Okay, you're the expert, you decide."

Li Shu is different from them; he is a criminal investigation expert who actually participates in solving cases and has solved many major cases.

Chen Yan brought the drawing board, but there was someone following behind her.

Sun Bomin!

Li Shu hurriedly stood up to greet him.

Sun Bomin sat down with a smile and said that he had just arrived and wanted to talk to Li Shu about something.

He glanced at the screen casually and asked curiously, "Is there a case? Someone died?"

Li Shu nodded and gave a brief explanation.

Upon hearing that five people had died, Sun Bomin's smile vanished instantly. He frowned, sighed softly, and said, "Li Shu, I'm starting to understand you a little."

He smiled, stood up, and said, "Li Shu, I've already discussed everything with Lao Liu. We'll handle the details. It's just benzenesulfonic acid, no big deal. It'll be ready in a month at most. Just wait for the inspection."

Li Shu clearly defined the chemical modifiers; for a prestigious institute of chemistry under the Chinese Academy of Sciences, such a minor matter is a piece of cake.

"And then, Li Shu, just wait to win the award and become famous in the chemistry world for your work on magnetic extraction."

He laughed again, patted Li Shu on the shoulder, and left with a flourish.

Clearly, they saw there was a case and didn't want to waste Li Shu's time.

Famous in the chemical community?

Wei Ranhui looked at Li Shu with a strange expression.

He just finished teaching a group of computer experts, and now he's going to make a name for himself in the chemistry world. That's quite a leap.

Sun Bomin didn't have time to explain the specifics of the discussion, and Li Shu didn't ask either.

With Liu Yaoqing involved, he's unlikely to treat me unfairly.

Then, with a clear objective, I wanted magnetic beads to get the technology for testing wastewater working.

That's fine then.

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But thinking about the NA subtype immediately gave me a headache again.

Picking up the drawing board, Li Shu stopped thinking and began playing the video.

Chen Yan brought over a drawing board and paintbrushes, but didn't leave. She stood quietly to the side, watching curiously.

"What, you want to learn?" Li Shu asked.

Chen Yan hummed in agreement. A composite sketch? Within the public security system, only a handful of people possessed this dragon-slaying skill. How could she not want to learn it? Then, embarrassed, she said, "The problem is, I've never been good at drawing since I was little."

She's good at science, but she's really bad at things like drawing, which are more humanities-oriented and artistic.

Because I lack something, I like what I lack, which is why I like art, watching movies, and listening to music.

Li Shudao said, "It's okay. I was just like you. I couldn't draw at first either. But when you learn, it's just basic sketching. I'm not asking you to become a painter. With more practice, you'll naturally get the hang of it."

He immediately gestured for Chen Yan to pull up a chair and sit down, then pointed to the screen and said, "Let's not draw yet, let's analyze the gait first."

If you're going to teach, then teach everything; gait analysis can be learned just as well.

"By the way, Director Wei, could you contact Su'an and have them send over the shoe prints collected from the scene?"

The suspect climbed over the wall and must have left shoe prints at the scene.

Wei Ranhui nodded and left.

Li Shu then pulled Chen Yan aside and taught her how to deduce a person's height and age by observing the changes in the center of gravity of their shoe prints.

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