Bab 7: Chapter 7 Brake Marks_1
Zhou Ning's doubts did not halt the task assignment flashing on the screen; green characters continuously popped up.
Reminder:
Please note, those who bind with the system, viewing the task reward content defaults to accepting the task!
Emergency Mission:
Locate the vehicle and perpetrator responsible for causing the victim's injury resulting in death. The task must be completed within 48 hours. Reward for completion: Level 3 Forensic Field Studies. First-time failure results in a deduction of one reward level.
Subsequently, the other characters on the screen disappeared, leaving only a 48-hour countdown timer. A sense of urgency instantly emerged.
Zhou Ning: ...
He wanted to curse, this was totally unreasonable, damn it, why didn't you mention these rules earlier?
Just one skid mark, what can that tell us?
Wait, skid mark...
Suddenly, a section from the textbook Forensic Field Studies flashed in Zhou Ning's mind, automatically searching for content related to the investigation of traffic accidents, specifically an important section on skid marks.
With a ruler in hand, Zhou Ning measured the width of the skid mark on one side more carefully, as well as the distance between the two skid marks, and estimated the wheelbase from the number 8-shaped pattern.
He acquired three values: tire width 235 millimeters, track width 1586 millimeters, wheelbase 2841 millimeters.
Seeing these numbers, Zhou Ning looked up at Zhao Xinli.
"Do you know about cars? If not, find someone who does."
Zhao Xinli stood to the side, watching Zhou Ning scribbling and drawing. He was somewhat puzzled by the sudden question but still nodded quickly.
"Look down on someone, huh! From F1 to the tricycle we use at home, I've studied them all. At twelve, I could disassemble any car my dad needed to fix. I have a basic understanding of any car on the market in our country. In our criminal police team, if I say I'm the second best, no one dares to claim they're the first. Just tell me what you need."
Zhou Ning, upon hearing this, quickly handed the clipboard to Zhao Xinli.
"I don't know if you guys have studied these marks before, but I measured them and came up with these three values. Can you tell what car it is?"
"Let me see, the traffic police team came before and determined these were sedan marks; we didn't let them investigate further."
Zhao Xinli glanced at it, interest piqued, squinted his eyes, and rapidly started searching on his phone. Zhou Ning watched, feeling a bit uncertain — relying on Baidu might not yield accurate results.
After a moment, Zhao Xinli held up his phone to Zhou Ning; it displayed an image with various figures, seemingly official data.
"These numbers match the Volkswagen CC 2010 model, 2.0TSI Luxury Edition. Look, it's exactly the same as the data you provided."
Zhou Ning nodded vigorously, his excitement barely containable.
"Notify Xu Da, we've identified the car model; it'll narrow down the search range."
Zhao Xinli grinned from ear to ear, pleased to make the joyful call — a sign of Zhou Ning's trust. He quickly got up to make the call.
Zhou Ning stood up and walked about ten meters north, where he discovered another cone marker and a slightly fainter skid mark. Although it didn't form the number 8, it was still two opposing C-shapes.
After measuring, he found the data to be completely different from the previous car: tire width 357 millimeters, track width 1590 millimeters, wheelbase 2780 millimeters.
A thought suddenly surfaced in Zhou Ning's mind — if there were two cars, could it be...
He shook his head, perhaps he was overthinking it.
Returning to the bloodstained skid mark, he knelt on one knee and used a small shovel to collect some of the rubber from the road surface.
Just now, when searching for skid mark content, a test report followed.
The report stated to extract the rubber from skid marks on the ground and compare it with rubber from a suspect's vehicle's tires to confirm the suspect vehicle.
Thinking this, that report reappeared in Zhou Ning's mind. This time, he didn't skim through but read it thoroughly.
This paper explores the analytical conditions of rubber pyrolysis using Pyrolysis Gas Chromatography-Mass Spectrometry [1], and examines rubber evidence in a traffic accident case using the established method and Scanning Electron Microscope-X-ray Energy Dispersive Spectroscopy.
By comparing known samples with the evidence and the differences in rubber compounds and inorganic elements between various samples, it is possible to match the evidence to the samples and to find that the tread rubber and sidewall rubber of different tires are each unique, and even components of tread rubber and sidewall rubber on the same tire differ.
This has valuable implications for the extraction of comparative samples from rubber evidence, providing objective foundations for the adjudication and litigation of cases.
The more he read, the more Zhou Ning nodded in agreement, he skipped the English section and looked below at the [Journal Name].
A file number: 2016(041)005, and Zhou Ning felt stunned.
This was an article six years later; could it be that the forensic field knowledge he had acquired was also from textbooks years ahead?
According to the system's prompt, what he had now was second-level forensic field knowledge, with the third level being even more meticulous and cutting-edge.
This discovery made Zhou Ning's heart race with excitement.
A weight on his shoulder, Zhao Xinli's large face moved in closer.
"Doctor Zhou, what are you thinking about? I've been talking to you, and you didn't hear me?"
Zhou Ning exhaled, suppressing his excitement, and packed the extracted rubber particles into an evidence bag before standing up.
"What's up? I didn't catch what you said."
"The boss said he'll be here soon."
Zhou Ning responded with an "Oh," thinking about the 48-hour deadline and still feeling some concern.
Just then, a sound of a car brake screeched nearby, a figure quickly got out of the car, crossed the police cordon, and ran up to them—it was Xu Dayuan, unable to contain the smile on his face.
"Not bad, Doctor Zhou, you keep surprising me today. Have you confirmed the car model?"
Zhou Ning truthfully shook his head.
"I'm not sure, but these three sets of data are correct. Zhao Xinli is familiar with cars; he found a Volkswagen CC 2010 2.0TSI advertisement and confirmed it matches with what we found at the scene."
Xu Dayuan nodded and glanced at the records in Zhou Ning's hand.
"Professionals are professional indeed. Our people found the brake marks but didn't get much information, only that it's a sedan, that it was speeding, and I didn't expect you to be able to match them up. I'll credit you for this."
As he spoke, Xu Dayuan made a call, inquired about these data, and received an accurate reply, which allowed him to breathe a sigh of relief.
"Confirmed, it's a Volkswagen CC 2010, the new model; Doctor Zhou, any other findings?"
Zhou Ning thought for a moment, then walked to the edge of the bloodstain.
"The victim was standing here when he was stabbed and didn't move afterward. Then he was hit and flung. Considering the distance of 112 meters the body was thrown and the car's own weight, even if the car braked for 4.5 meters, the speed was still over 100 mph, so it must've been even higher before braking.
Based on the rectal temperature, the estimated time of death is 2:23 a.m. Doctor Liu's report asked me to write between 2:00 to 3:00 a.m. During this time, with such high speed, the key is I also found brake marks from another car parallel to this one, and I'm wondering if there was illegal racing involved?"
Zhao Xinli and Xu Dayuan both looked at Zhou Ning. After he finished speaking, both were silent, and Zhou Ning suddenly felt nervous. Was his speculation too far-fetched?
At that moment, Xu Dayuan kicked at Zhao Xinli in anger.
"You idiot! I went to check the victim's identity, and asked you to lead the team here to find the scene marks, and you saw nothing!"
Zhou Ning was taken aback and dared not speak.
"Doctor Zhou, quickly show me the brake marks you found."
Zhou Ning led them over, glancing apologetically at Zhao Xinli, only to find the young man completely unfazed and keenly following along with a still cheerful grin on his face.
"Take it easy, boss. I just noticed these marks looked similar, but compared to the ones with the bloodstains, these are much lighter and longer in brake distance."
Xu Dayuan waved his hand dismissively.
"Stop making excuses for them, check quickly. What is this data, and can you tell the car model?"
Zhao Xinli was already on the side, ready to jump in, glanced at the three sets of data, and quickly started browsing on his phone. After a long search with no conclusion, Xu Dayuan raised his leg already.
Zhao Xinli dodged to the side, his fingers seeming to zoom in on a picture, then he exclaimed in surprise.
"Damn, is this even real? Does someone in our county drive such an expensive car?"
......
PS:
[1]Pyrolysis Gas Chromatography-Mass Spectrometry:
In traffic accident cases, the friction and skidding of vehicle tires with other objects, including brake action against the ground, often transfer rubber particles either to the contact object or leave them on the ground, forming brake marks. Examining these rubber particles can provide evidence for reconstructing the facts and determining the culpable vehicle.
Automobile tires are often made of natural rubber (NR), polybutadiene rubber (BR), and styrene-butadiene rubber (SBR), used singly or in combination, with the addition of vulcanizing agents, accelerators, antioxidants, fillers, and other organic or inorganic additives. It is possible to accurately determine the type of rubber based on characteristic pyrolysis products. In combination with SEM-EDX, it allows for comprehensive analysis of both organic components and inorganic elements in rubber, becoming an important means for rubber examination and identification in recent years.
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