Chapter 1178: Not Easy

"Screening?"

Busy until dark, the Image Investigation Team Captain sought out Jiang Yuan for instructions.

Their progress in the early stages was very fast; in just half a day, they had found the surveillance footage of the suspicious vehicle. If not for the fact that the night-vision capabilities of several cameras were too weak, this case should have been a classic example of a swift resolution.

For the same reason, in a situation where the existing surveillance footage was useless, all the Image Investigation Team could do was conduct a large-scale screening of vehicles during the time of the incident.

Logically speaking, the suspicious vehicle drove past the wall of the stolen-from company at 4:10 AM and turned around 300 meters ahead at 4:50 AM, so the time of the crime was basically determined. If they extended the time slightly and checked the vehicle checkpoints on the national highway and expressway—especially the national highway checkpoints—there was a high probability they could catch the suspicious vehicle.

However, this job was definitely not easy.

Traffic around Changyang City was busy; even at 4:00 AM, there were still many vehicles coming and going, especially freight vehicles, some of which specifically ran at night.

Without knowing other information about the vehicle, screening vehicles passing through the national highway for an hour or even longer—especially with so many out-of-province vehicles—would be a workload on the level of Xu Taining.

Jiang Yuan had done quite a few similar screening tasks. If nothing else, to quickly obtain vehicle information, they would have to send people to other provinces or even different cities. For those who were difficult to talk to, or where local work was busy, someone would have to coordinate, and the forces mobilized would include but not be limited to Yu Wenshu, Jiang Yuan, the Provincial Department, and even the Ministry...

And once the screening reached this point, according to Xu Taining's screening theory, it would be best to screen the vehicles passing through the expressway as well. Although the probability was low, since they had already reached this point, increasing the quantity by several times was a minor matter...

"Although it's a method, the efficiency is too low." Jiang Yuan had been thinking about this the whole time. At this moment, he didn't completely reject the Image Investigation Team Captain's opinion, but he looked at Liu Jinghui and asked, "What does Director Liu think?"

"If we are to screen like this, the clues we currently have are not enough." Liu Jinghui analyzed calmly: "We initially determined it was an inside job. After screening the relevant vehicles, we also have to compare them with the factory's staff list and former staff list... In a normal process, this investigation strategy is definitely fine, but for a super-large-scale screening, the evidence we have obtained so far is too insufficient."

Wang Chuanxing, who had been following along to take notes, said leisurely: "Determining the perpetrator is an insider—that's your deduction, Director Liu."

Liu Jinghui looked at Wang Chuanxing with sharp eyes: "Deduction! Not evidence! Don't talk about evidence!"

The Image Investigation Team Captain also realized that the screening he mentioned represented a huge workload and investigation cost, as well as the responsibility he would have to bear, and couldn't help but want to back out: "Since Director Liu has started talking about evidence, then we should indeed look for more evidence."

Liu Jinghui felt his waistline expanding with anger and repeated: "Deduction is a judgment given after synthesizing evidence from all sides... How about screening footprints?"

Liu Jinghui was extremely familiar with the skills Jiang Yuan had mastered.

The most common evidence in theft cases is of two types: one is fingerprints, the other is footprints. For ordinary criminal police, the former is the most common, but for higher-level theft cases, footprints are a lethal weapon. Thieves can avoid fingerprints by wearing gloves, but they can't float in mid-air to enter and exit homes.

Although the footprints at the crime scene were numerous, messy, and often damaged, in the final analysis, they were just the footprints of a few dozen people. If Jiang Yuan were to identify them one by one and investigate these few dozen people separately, it would be a viable path.

Jiang Yuan lowered his head and glanced sideways at Liu Jinghui: "The factory workers have little span in height, weight, and age, and they are engaged in the same profession, all wearing acid-and-alkali-resistant work shoes issued by the factory. Plus, with repeated trampling, it's very difficult to match the footprints to the individuals."

"Does 'very difficult' mean it can be done, but it's laborious?" Liu Jinghui tried to translate.

"Not only that," Jiang Yuan said. "To compare them one by one, we need samples."

Liu Jinghui translated again: "In other words, theoretically, we could bring in the footprints of all current employees for analysis and comparison. If there are footprints at the scene that aren't from current employees, we can judge them to be the suspect's. But to determine the identity of that suspect, we still need footprints for comparison, which means we'd have to send criminal police to find all the former employees and take their footprints..."

Without Jiang Yuan needing to say more, Liu Jinghui realized the difficulty: "The number of former employees is large, and they might not all still be in the province. Moreover, the criminal might deliberately avoid our investigation... Well, if it's a conspiracy, the footprints left at the scene could even be from a perpetrator who is completely out of sight."

The last point was the most fatal, lowering the feasibility of footprint screening by more than two grades. Of course, it wasn't that it couldn't be used; if there were absolutely no other clues, this plan could barely be tried.

An investigation direction that guarantees a 100% answer is harder than catching a blade with bare hands.

"Let me think again..." Liu Jinghui entered a state of self-innovation.

Jiang Yuan, however, had been thinking for a long time. Seeing this, he said, "In that case, I think we should just analyze the vehicles."

"How to analyze?" the Image Investigation Team Captain asked immediately. He had been watching the video for so long and still had no ideas.

"We can't see the suspicious vehicle from the surveillance footage, but look here..." Jiang Yuan took out the footage of the vehicle turning around and said, "Although we can't see the shape of the car, the image of the vehicle's headlights shining on the ground is still very clear."

"This..." the Image Investigation Team Captain looked at Jiang Yuan, not knowing what to say or what to ask.

Jiang Yuan said directly, "I think we can analyze the arrangement characteristics of the vehicle's headlights. The headlight arrangement of different vehicles is different. Although there are 'nesting doll' cars, if we can determine a brand, it can still reduce a lot of workload."

"Can it be done?" Liu Jinghui's spirits lifted, and his ongoing thinking stopped.

Jiang Yuan nodded: "We can try."

Jiang Yuan also had LV3 Vehicle Trace Identification. Combined with corresponding image investigation technology, narrowing down the scope shouldn't be a problem.

Wei Shiyan, who had been listening with ears pricked up, leaned over, looked at the two blurry beams of light on the screen in front, and asked hesitantly, "How do we analyze this? Using math?"

"Do you have any ideas?" Jiang Yuan asked Wei Shiyan in return.

Wei Shiyan really thought about it, then his whole body trembled violently, and he whispered tentatively: "Using linear algebra?"

Although he hadn't studied it seriously, he had indeed been buried by linear algebra for two days.

Jiang Yuan looked at Wei Shiyan and asked curiously, "How to use it?"

"Calculate based on the projected area?" Wei Shiyan tried to say: "Maybe we can estimate the height of the vehicle or something..."

Jiang Yuan listened earnestly, then nodded and said, "You can try it. Just treat it as your homework."

"Oh... wait, do I do it myself? What about you?" Wei Shiyan asked hurriedly.

"We'll go to the scene to experiment." Jiang Yuan gestured on the screen with his fingers and said, "At the scene, just measure the distance between these two points, and we'll know the headlight spacing. Then find a car, drive it to the same position, and look at the position of the headlights, and we can judge the vehicle height..."

Jiang Yuan explained it roughly, and the few people beside him all understood.

Wei Shiyan also understood, but he didn't understand and asked, "So, what is linear algebra used for?"

Looking up, Jiang Yuan and the others had already walked far away. ===== CHAPTER 1179 =====