CHAPTER 1265: CHAPTER 1192: NOT EASY

"Are we going to investigate?"

As it got dark, the Chief of Image Investigation came over to seek instructions from Jiang Yuan.

Their progress was swift in the early stages. Within half a day, they had retrieved the surveillance video of the suspect vehicle. If it weren’t for the poor night shooting capability of several cameras, this case should have been a textbook example of a quick solve.

For the same reason, given that the current surveillance videos were unusable, the only thing the Image Reconnaissance Brigade could do was to conduct a large-scale investigation of vehicles during the time of the crime.

Theoretically, the suspect vehicle passed by the wall of the robbed company at 4:10 AM, and turned around 300 meters ahead at 4:50 AM. The crime time was basically determined. If the time was slightly extended and they checked the checkpoints for vehicles on the national and highway roads, especially the national road checkpoints, the suspect vehicle could most likely be caught.

However, this task was definitely not easy.

The traffic around Changyang City was busy, even at 4 AM, there were still quite a few vehicles coming and going, especially freight vehicles, some of which specifically operated at night.

In the absence of other vehicle information, investigating vehicles passing through the national road for an hour, or even a bit longer, especially with so many vehicles from other provinces, would be work of Xu Taining’s level.

Jiang Yuan had also done similar investigations quite a few times. To quickly obtain vehicle information, one had to send people to other provinces, or even different cities. Some places were hard to deal with, or local work might be busy and would require someone to assist and coordinate, utilizing forces including but not limited to Yu Wenshu, Jiang Yuan, the provincial department, and even the ministry...

Once the investigation reached this point, by Xu Taining’s investigation theory, it was best to investigate all vehicles passing through the highway once. Although the probability was low, having reached this stage, increasing the quantity by several times was actually a minor issue...

"Although it’s a method, the efficiency is too low." Jiang Yuan was constantly pondering and didn’t entirely dismiss the Chief of Image Investigation’s suggestion but instead looked at Liu Jinghui and asked, "What does Director Liu think?"

"If we are to investigate this way, the clues we currently have are insufficient." Liu Jinghui calmly analyzed, "We preliminarily identified it as an inside job. After investigating the related vehicles, we also need to compare them with the employee and ex-employee lists of the chemical factory. Normally, this investigation strategy would have no problem, but for an ultra-large investigation, the evidence we’ve gathered so far is too inadequate."

Standing beside them, Wang Chuanxing, who had been taking notes, calmly said, "Determining that the perpetrator was an inside job was your inference, Director Liu."

Liu Jinghui shot a sharp glance at Wang Chuanxing, "Inference! Not talking about evidence!"

The Chief of Image Investigation also realized the enormous workload, investigation costs, and the responsibility he had to bear from his suggestion of investigation, and was hesitant too, "Since even Director Liu is talking about evidence, we really should find more evidence."

Liu Jinghui felt his waistline expanding due to anger, repeating, "Inference is a judgment made when evidence from all sides is integrated... How about conducting footprint analysis?"

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

For theft cases, the most commonly used evidence is of two types: fingerprints and footprints. For regular detectives, the former is most commonly used, but for more advanced theft cases, footprints are the killer weapon. Thieves can avoid fingerprints by wearing gloves, but they can’t enter and exit houses floating in mid-air.

Although the footprints at the crime scene were messy and oftentimes damaged, ultimately, they were only the footprints of dozens of people. If Jiang Yuan could identify them one by one and then investigate these dozens of people separately, it would be a viable approach.

Jiang Yuan tilted his head and looked askance at Liu Jinghui, saying, "The factory workers have little range in height, weight, and age. Since they perform the same job and wear the same acid and alkali resistant work shoes issued by the factory, coupled with repeated trampling, it’s very difficult to match footprints to individuals."

"Does ’very difficult’ mean it can be done but is laborious?" Liu Jinghui attempted to translate.

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

Liu Jinghui translated again, "So theoretically, we could collect the footprints of all current employees for analysis and comparison. If there are footprints at the scene from non-current employees, we could consider them suspects. However, to confirm the suspect’s identity, we’d still need footprints for comparison, meaning detectives would need to be sent to find former employees and collect their footprints..."

Without Jiang Yuan saying more, Liu Jinghui already realized the difficulty: "The number of former employees is large and they may not all still be in the province. Moreover, the criminal might deliberately avoid our investigation... And if it was a conspiracy, the footprints left at the scene might belong to completely uninvolved accomplices."

The last point was the most lethal, reducing the feasibility of footprint investigation by two notches. Of course, it’s not that such an approach can’t be used, if there are no other clues at all, this plan can be reluctantly tried.

Investigation paths that guarantee a 100% answer are even more difficult than catching a blade barehanded at a hundred percent.

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

Jiang Yuan had already thought for a long time and, seeing this, said, "In that case, I think we might as well analyze the vehicle."

"How do we analyze it?" The Chief of Image Investigation immediately asked. He had also watched the video for so long and still had no idea.

"We can’t see the condition of the suspicious vehicle from the surveillance video, but look here..." Jiang Yuan pulled up the surveillance from when the vehicle turned around, saying, "Although the car itself is not visible, the image of the headlights projected onto the ground is very clear."

"This..." The Chief of Image Investigation looked at Jiang Yuan, not knowing what to say or ask.

Jiang Yuan plainly stated, "I think we can analyze the headlight arrangement characteristics of the vehicle. The headlight arrangements of different vehicles are still different. Although there are copycat cars, determining a brand can still reduce a lot of workload."

"Can this be done?" Liu Jinghui suddenly got interested, halting his ongoing thought process.

Jiang Yuan nodded, "We can give it a try."

Jiang Yuan still had LV3 vehicle trace identification skills, and with the appropriate image investigation techniques, narrowing down a certain range should not be a problem.

Wei Shikan, who had been listening in with his ears perked, came over at this moment, looking at the two blurry beams on the screen ahead, hesitantly asking, "How do you analyze this? Using math?"

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

Wei Shikan really thought for a moment, then shivered slightly, cautiously suggesting, "Using linear algebra?"

Although he hadn’t seriously studied it, he really had been buried under linear algebra for two days.

Jiang Yuan looked at Wei Shikan curiously and asked, "How would you use it?"

"Calculate based on the projection area?" Wei Shikan tried to say, "Maybe we can estimate the vehicle’s height..."

Jiang Yuan listened seriously, then nodded and said, "You can try it; just consider it your homework."

"Oh... huh, I do it myself? Then what about you?" Wei Shikan hurriedly asked.

"We’ll just go to the scene and experiment." Jiang Yuan pointed to the screen with two gestures, saying, "At the scene, directly measure the distance between these two points, and you’ll know the distance between the headlights. Then find a car, drive it to the same position, and see the headlight positions; you can then determine the vehicle height..."

Jiang Yuan roughly explained, and the few people around all understood.

Wei Shikan also understood, but didn’t understand enough to ask, "So, what is linear algebra used for?"

Raising his head, Jiang Yuan and the others had already walked away.