Chapter 7 Brake Tracks
Zhou Ning's doubts did not stop the tasks from being released on the display screen, and green words kept popping up.
hint:
Please note that if you choose to view the task reward content, it will be deemed as accepting the task!
Temporary duty:
Find the vehicle and the person who hit the deceased. The task must be completed within 48 hours. The reward for completion is the third level of forensic on-site training. If the task fails, the initial reward will be reduced by one level.
Immediately, the other words on the screen disappeared, leaving only a 48-hour countdown, and the sense of urgency instantly emerged.
Zhou Ning: ...
He wanted to curse, this is simply unreasonable, damn, there is such a rule, why didn’t you tell me earlier?
It's just a brake mark. What can it tell us?
Wait, skid marks...
The book "Forensic Scene Science" suddenly popped up in Zhou Ning's mind, and he automatically searched for a section about the investigation of the car accident scene. One of the important parts was the brake marks.
Holding a ruler, Zhou Ning measured the width of the brake mark on one side and the distance between the two brake marks more carefully this time, and estimated the wheelbase at the figure-8 mark.
The three values obtained are: tire width 235 mm, wheelbase 1586 mm, and wheelbase 2841 mm.
Seeing these numbers, Zhou Ning looked up at Zhao Xinli.
"Do you know anything about cars? If not, find someone who does."
Zhao Xinli stood on one side, watching Zhou Ning writing and drawing. He was a little confused by such a sudden question, but he nodded quickly.
"You look down on me, don't you? I've studied everything from F1 to the tricycles we use at home. When I was twelve years old, I could dismantle the car my dad wanted to repair. As long as the car is on the market and available in China, I know a little bit about it. In our criminal police team, if I say I'm second, no one dares to say I'm first. What do you want to do?"
When Zhou Ning heard this, he quickly handed the splint in his hand to Zhao Xinli.
"I don't know if you have studied these traces before. I measured them and got these three values. Can you tell what kind of car it is?"
"Let me see. The traffic police came over and determined that it was a car, so we didn't let them go up."
Zhao Xinli took a quick glance , became interested, blinked his eyes, and quickly opened his phone to search. Zhou Ning felt a little unsure when he saw it. If he looked on Baidu, the information might not be accurate.
After a moment, Zhao Xinli held up his mobile phone in front of Zhou Ning. On it was a picture with various data, which seemed to be official content.
"The car that best matches these data is the Volkswagen CC 2010 2.0TSI Premium Model, which is exactly the same as the data you gave."
Zhou Ning nodded vigorously, his face showing uncontrollable excitement.
"Please inform Xu Da. If we find the model of the car, we can reduce the search area."
Zhao Xinli smiled with his teeth showing. He asked him to make the call to report the good news. This showed Zhou Ning's trust in him. He quickly got up and made the call.
Zhou Ning stood up and walked north for more than ten meters. He found that there was also a tower cone sign here and a slightly lighter brake mark. Although there was no 8 at the end, there were two opposite C shapes.
After measuring the data, I found that it was completely different from the previous one. The tire width was 357 mm, the wheelbase was 1590 mm, and the wheelbase was 2780 mm.
An idea suddenly appeared in Zhou Ning's mind. If there were two cars, could it be...
He shook his head, perhaps he was overthinking.
Go back to the bloody brake tracks, kneel on one knee, and use a small shovel to scoop up some rubber from the road surface.
When I was searching for the term brake marks just now, it was followed by an inspection report.
The report said that the rubber from the brake marks on the ground was extracted and then compared with the rubber from the wheels of the suspect's vehicle to identify the suspect vehicle.
As he was thinking about it, the report appeared in Zhou Ning's mind again. This time he did not just glance over it, but read it carefully.
This paper explores the gas chromatography-mass spectrometry analysis conditions of rubber cracking [1], and uses the established method and scanning electron microscopy-X-ray spectroscopy to examine rubber evidence in a traffic accident case.
By comparing the similarities and differences between the test materials and samples and between the rubber compounds and inorganic elements of different samples, the test materials and samples can be compared and identified, and it is found that the tread rubber and sidewall rubber compositions of different tires are different, and even the tread rubber and sidewall rubber compositions of the same tire are different.
This has guiding value for the extraction of rubber physical evidence comparison samples and provides an objective basis for the trial and litigation of the case.
The more he looked, the more Zhou Ning nodded, crossing the English part and below [Journal Name].
There was a [year (volume) issue] 2016 (041) 005, Zhou Ning was stunned.
This is an article written six years later, so wouldn’t the forensic on-site knowledge I have acquired also be useful as teaching materials in a few years?
According to the system prompts, what I have now obtained is the second-level forensic on-site training, and the third level is more detailed and advanced knowledge.
This discovery made Zhou Ning's heart beat faster with excitement.
His shoulders sank, and Zhao Xinli's big face moved closer.
"What are you thinking about, Xiao Zhou, forensic doctor? Didn't you hear me talking to you?"
Zhou Ning exhaled, suppressed his excitement, put the extracted rubber particles into an evidence bag, and stood up.
"What's wrong? I didn't pay attention to what you said."
"The boss said he'll be here soon."
Zhou Ning said "oh" and felt a little worried when he thought about the 48-hour deadline.
Just then, there was a sudden brake sound not far away, and a figure quickly got out of the car, crossed the cordon, and ran to their side. The person was Xu Dayuan, and the smile on his face could no longer be suppressed.
"Sure, Xiao Zhou, you've given me many surprises today. Are you sure about the model of the car?"
Zhou Ning shook his head honestly.
"I'm not sure, but there is no problem with these three sets of data. Zhao Xinli is very familiar with cars. He found a promotional poster of the Volkswagen CC 2010 2.0TSI and compared it with the one found at the scene."
Xu Dayuan nodded and looked at the records in Zhou Ning's hand.
"Professionals are professionals. Our people found brake marks, but we didn't get much information. We just knew it was a sedan and it was speeding. I didn't expect to be able to match these. I'll give you credit."
As he said that, Xu Dayuan made a phone call and asked the person about the data. The other party gave an accurate answer, and he finally breathed a sigh of relief.
"It's confirmed. It's the Volkswagen CC 2010 model. Does Xiao Zhou have any other findings?"
Zhou Ning thought about it and walked to the edge of the bloodstain.
"The deceased was standing here when he was stabbed, and he did not move. He was then knocked away. According to the distance of 112 meters that the body flew, and the weight of the vehicle , even if the car braked for 4.5 meters, the speed was more than 100 miles per hour, so the speed before the brakes would be even higher.
According to rectal temperature, the time of death was 2:23 in the morning. In the report, Forensic Doctor Liu asked me to write between 2:00 and 3:00. During this time period, the car was driving at such a high speed. The key is that I found brake marks of another car running parallel to this car. I wonder if someone was illegally racing?"
Zhao Xinli and Xu Dayuan both looked at Zhou Ning. After they finished speaking, they both fell silent. Zhou Ning was a little nervous for a moment. Could it be that his guess was outrageous?
At this moment, Xu Dayuan kicked Zhao Xinli with anger on his face.
"You bastard, I went to check the identity of the deceased and asked you to lead the team to search for traces at the scene, but you didn't even look at shit!"
Zhou Ning was stunned and didn't dare to speak.
"Xiao Zhou, forensic doctor, take me to see the brake mark you found ."
Zhou Ning led them over and glanced at Zhao Xinli apologetically, only to find that this boy had no idea what embarrassment was. He followed with great interest, still smiling.
"Don't worry, leader. I just saw that the marks here are somewhat similar. However, compared to the brake marks with blood, these are much lighter and the braking distance is also longer."
Xu Dayuan waved his hand.
"Don't make up for them. Check it out quickly. What is the data? Can you tell us the model of the car?"
Zhao Xinli was already eager to try at the side. He glanced at the three data and quickly browsed them on his mobile phone. After looking through them for a long time without any follow-up, Xu Dayuan had already raised his leg.
Zhao Xinli dodged to the side, his fingers seemed to be enlarging the picture, and then he let out a cry of surprise.
"Oh my god, is this true? Is there anyone in our county who drives such an expensive car?"
…
PS:
【1】Pyrolysis gas chromatography-mass spectrometry:
In traffic accidents, the scraping and bumping of vehicle tires and other objects, and the sliding friction between the brakes and the ground will cause rubber particles to be transferred to the contacted objects or left on the ground to form brake marks. Testing these rubber particles can provide evidence for restoring the truth and identifying the vehicle that caused the accident.
Automobile tires are mostly made of natural rubber (NR), butadiene rubber (BR) and styrene butadiene rubber (SBR) alone or in combination, with the addition of organic or inorganic additives such as vulcanizers, accelerators, antioxidants, fillers, etc. The ability to accurately identify the type of rubber based on characteristic pyrolysis products and combined with SEM-EDX method can be used to conduct a comprehensive analysis of the organic components and inorganic elements in rubber, which has become an important means of rubber inspection and identification in recent years.
