Diary of a Criminal Investigator

Lu Chuan had system-awarded skills in tire tread pattern identification and analysis.

Within trace identification, it includes different tire types, different tire pressures, different degrees of tire wear, and even different tire models and types, affecting the trace.

Simply put, even tracks left by the same tire on different surfaces can vary.

Or, the tracks left by the same tire on the same surface can differ because of different tire pressures.

The impact of tire tracks is controlled by several factors, such as pressure, temperature, surface conditions, and the degree of tire wear.

It is an extremely complex identification and analysis process with high comprehensive difficulty.

This identification and analysis performed by Lu Chuan was relatively simple, as the burst marks caused by tire compression and cuts from sharp tools were completely different.

During the manufacturing process, tires are made to keep a specific thickness of the sidewalls and tread as much as possible.

However, in actual use, after wear, the thickness of the sidewall, especially the tread, can become unevenly worn.

This wear can lead to some parts of the tire being thinner and others thicker.

Moreover, during driving, the tire inevitably experiences some bumps, causing the tread or sidewall to peel.

This would result in certain areas of the tire being much thinner than others, and during compression, the thinner areas are weaker and likely to burst first, forming tear marks.

For all four tires, Lu Chuan found the results to be natural tears, with no signs of neat cuts from sharp tools.

Therefore, from this perspective, the suspect apparently had not tampered with the tires.

Brakes.

Next, Lu Chuan focused on inspecting the brake hydraulic system.

Most passenger cars use hydraulic brake systems.

Thus, the pressure of the brake hydraulic fluid is a crucial factor in determining the braking power.

Moreover, hydraulic hoses are generally exposed, making it relatively easy for a suspect to tamper with them by simply crawling under the car and cutting the hydraulic hose, which could cause brake failure.

Although the vehicle had been compressed, parts of the undercarriage’s oil system were still visible.

Due to compression, the vehicle’s oil system was damaged, and the entire undercarriage was a black mess of oil, making it difficult for Lu Chuan to assess just by looking.

"Engineer Zhang, you’re familiar with vehicles, help me find the brake hydraulic pipeline?"

Engineer Zhang was the operator of the compression machine.

"Alright, alright, I’m familiar with this, let me take a look."

Realizing the gravity of his mistake, the operator was more than eager to assist to make amends.

"Here, this is the brake hydraulic hose of the left front wheel."

Being a true professional, he found a greasy hose in no time.

Brake hoses are typically made from one of two materials: metal and rubber.

Older vehicles had brake hoses made of rubber, but since rubber deteriorates over time, this can cause damage to the hydraulic hose, resulting in low hydraulic fluid pressure and brake failure. Eventually, higher-end models switched to using metal hydraulic hoses.

However, due to cost reasons, many lower-end models continue to use rubber hoses.

The police car driven by Ren Qiang was purchased just three years ago, and its features were fairly decent, ensuring at least some level of safety, or otherwise, Ren Qiang wouldn’t have only broken a leg and an arm.

The brake hoses of the vehicle were also made of metal.

Theoretically, due to the compression, the hose should have been damaged or burst, but the hose found by Engineer Zhang showed no signs of bursting, only some deformation.

All four hoses were still on the ground, showing only minor deformations; even the connectors were intact.

"This... doesn’t add up, why didn’t the hose burst after compression?"

The compression machine operator also noticed an anomaly.

Lu Chuan picked up the hose and examined it closely, discovering a small sawed hole on the hose initially fitted to the left rear wheel.

"The brake fluid likely all leaked out from this small hole."

With no brake fluid, the brakes would naturally fail, which was the culprit behind Ren Qiang’s car accident at North Mountain.

This evidence pointed to a human cause behind the car accident.

After placing the hydraulic hose into a bag to be used as evidence, Lu Chuan intended to conduct an examination later; if the perpetrator was careless and didn’t wear gloves, fingerprints might be found on the hose.

"Secure the vehicle and allow no one to touch it."

"Don’t worry, I’ll personally supervise it to ensure no one tampers with it at all."

Having instructed Engineer Zhang, Lu Chuan returned to find Zhang Hui.

Zhang Hui, who was investigating the reporting records of the tow truck, should have found some leads by now.

Parking lot office.

Upon seeing Lu Chuan return, Zhang Hui immediately asked, "How did it go? Did you find anything?"

"Yes," Lu Chuan replied, pulling out the evidence bag containing the brake hose: "The brake hydraulic hose for the left rear wheel has a small sawed hole."

"The hole isn’t very big, so the brake fluid wouldn’t have leaked out immediately, meaning everything was probably fine when Brother Qiang started driving. However, after frequent use of the brakes, the brake fluid completely leaked from this hole, leading to brake failure when reaching North Mountain, resulting in the accident."

As suspected, the car accident was deliberately engineered, and now, concrete evidence was finally found.

"Damn it, these people have some nerve!"

Zhang Hui, having worked as a detective for so many years, had never encountered such a situation before.

Moreover, it was a highly unnerving matter upon further consideration.

Why would someone target Ren Qiang?

Ren Qiang’s return from Liangzhou City was a last-minute decision, not a planned arrangement.

Clues about the Songbei Mining case couldn’t have been known beforehand, right?

Additionally, the car Ren Qiang drove was a police vehicle, so how did the perpetrator even find this particular car?

And how did they know where it was parked?

Upon careful reflection, these questions appeared very puzzling.

"Brother Hui, how are things on your end?"

"Switched license plates, the tow truck had fake plates."

The reason the tow truck in the video could enter the parking lot was that the barrier system at the entrance recognized the truck’s license plate number.

That license plate was indeed registered with the traffic police department.

However, after a call verification just now, it was confirmed that all the vehicles with that plate number were under repair, torn apart into pieces at the repair shop for the past week, making it impossible for that tow truck to have been at North Mountain to tow away the police car today.

Hence, it’s certain that the perpetrator forged the license plate number and then entered the parking lot at North Mountain.

"I’ve already asked the traffic police to investigate. The tow truck can’t just vanish after leaving the parking lot. Given its size, let’s see if we can find it."

Zhang Hui, who’s meticulous in procedural matters, wouldn’t make rookie mistakes.

"This is roughly our situation here, we need to report back to Captain Qin."