novice forensic medicine

Chapter 7 Brake marks
Zhou Ning's doubts did not stop the task release on that screen, and the green words kept popping up.

prompt:

Please pay attention to the binding person, if you choose to view the task reward content, you will accept the task by default!
temporary assignment:

To find the vehicle and the perpetrator who hit and injured the deceased, the task must be completed within 48 hours, and the reward for completing the forensic field study is three levels, and the first time the task fails, the reward will be reduced by one level.

Immediately, the other writing on the screen disappeared, leaving only a 48-hour countdown, and the sense of urgency came out instantly.

Zhou Ning: .
He wants to scold his mother, which is simply unreasonable. Ma Dan has such a rule, why didn't you say it earlier?
Just a brake mark, what can this thing indicate?
Wait, brake marks.
Zhou Ning's on-the-spot forensic science book suddenly popped up in Zhou Ning's mind, and he automatically searched for a section about the investigation of the scene of the car accident, and one of the most important sections was the brake marks.

Holding a ruler, Zhou Ning carefully measured the width of the brake marks on one side and the distance between the two brake marks more carefully this time, and estimated the wheelbase from the figure 8 marks.

Get three values: tire width 235 mm, wheelbase 1586 mm, wheelbase 2841 mm.

Seeing these values, Zhou Ning looked up at Zhao Xinli.

"Do you know cars? If you don't know, find someone who does."

Zhao Xinli stood on one side, watching Zhou Ning write and draw. Suddenly, he was a little dazed by such a question, but he nodded quickly.

"You look down on people, don't you! I have studied everything from F1 to the three-wheeled car used at home. I can dismantle the car my dad wants to repair at the age of 12. As long as the car on the market is available in China, I basically know a little bit. , As far as our criminal police team is concerned, I say second, no one dares to say first, what do you think you want to do?"

Upon hearing this, Zhou Ning quickly handed the splint 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's see, the traffic police came over and judged that it was a trace of a car, and we didn't let it go."

Zhao Xinli glanced at it, became interested, blinked his small eyes, and quickly turned on his mobile phone to look for it. Zhou Ning felt a little confused when he saw it. If he was looking for Du Niang, it might not be accurate.

After a while, Zhao Xinli held up the mobile phone in front of Zhou Ning. On it was a picture with various data, which seemed to be the content released by the government.

"These data are most consistent with the Volkswagen CC 2010 2.0TSI premium model. It seems to be completely consistent with the data you gave."

Zhou Ning nodded vigorously, with uncontrollable excitement on his face.

"Please inform Xu Da, if you find the model, the search range will be less."

Zhao Xinli smiled blindly, and asked him to call to announce the good news. This is Zhou Ning's trust in him, so he quickly got up and called.

Zhou Ning stood up and walked north for more than ten meters, and found that there was also a tower cone sign, a slightly lighter brake mark, although there was no 8 at the end, it was also two opposite C shapes.

After measuring the data, it was found that it was completely different from the one just now, with a tire width of 357mm, a wheelbase of 1590mm, and a wheelbase of 2780mm.

An idea suddenly appeared in Zhou Ning's mind. If there were two cars, could it be
He shook his head, maybe he was thinking too much.

Going back to the bloody brake marks, I knelt down on one knee and used a small shovel to scoop up some rubber on the road surface.

When I was searching for the content of the brake marks just now, it was followed by an inspection report.

The report stated that the rubber in the brake marks on the ground was extracted, and then compared with the wheel rubber of the suspect's vehicle to identify the suspect vehicle.

Thinking, that report reappeared in Zhou Ning's mind, this time he didn't sweep it all away, but looked at it seriously.

This paper explores the gas chromatography-mass spectrometry [1] conditions for rubber cracking, and uses the established method and scanning electron microscope-X-ray energy spectrometry to examine the rubber evidence in a traffic accident case.

By comparing the test materials and samples and the similarities and differences of the rubber compound and inorganic elements between different samples, the comparison and identification of the test materials and samples were realized, and it was found that the components of the tread rubber and sidewall rubber of different tires were different, and even the same tire There are also differences in the composition of tread rubber and sidewall rubber.

This has guiding value for the extraction of rubber material evidence comparison samples, and provides an objective basis for the trial and litigation of the case.

The more you look, the more Zhou Ning nods, stepping over the English part, under [Journal Name].

There is a [year (volume) period] 2016 (041) 005, Zhou Ning is stupid.

This is an article six years later, so the forensic on-the-spot studies I got are not the textbooks a few years later?
According to the system prompt, what I got now is the second-level forensic on-site study, and the third-level is more detailed and more avant-garde knowledge.

This discovery made Zhou Ning's excited heart beat faster.

His shoulders sank, and Zhao Xinli's big face came closer.

"Xiao Zhou, forensic doctor, what are you thinking? Didn't you hear me talking to you?"

Zhou Ning exhaled, suppressed his excitement, packed the extracted rubber particles with a physical evidence bag, and stood up.

"What's wrong, I didn't pay attention to what you said."

"The boss said, he will be here soon."

Zhou Ning let out a sigh, thinking of the 48-hour deadline, he was still a little worried.

At this moment, a sudden brake came from not far away, and a figure quickly got out of the car, crossed the cordon, and ran to their side. It was Xu Dayuan who came, and the smile on his face could no longer be suppressed.

"Okay, forensic doctor Xiao Zhou, you have given me a lot of surprises today. Are you sure about the model?"

Zhou Ning shook his head honestly.

"I'm not sure, but these three sets of data are all right. Zhao Xinli is very familiar with cars. He found the publicity poster of the 2010 Volkswagen CC 2.0TSI. After comparison, it is indeed the same as the one found on the spot."

Xu Dayuan nodded, and looked at the record in Zhou Ning's hand.

"Professionals are professionals. Our people found the brake marks, but they didn't get much information. They knew it was a car and it was in a speeding state. I didn't expect to be able to compare these. I will give you a credit."

After speaking, Xu Dayuan made a call and asked the person for the data, and he was relieved when the other party gave an accurate answer.

"It's confirmed, it's the new Volkswagen CC2010, did Xiao Zhou's forensic doctor find anything else?"

Zhou Ning thought for a while and walked to the edge of the bloodstain.

"The deceased was stabbed standing here at the time, did not move after that, and then was knocked into the air. According to the distance of the body flying 112 meters and the weight of the vehicle, even if the car braked for 4.5 meters, the speed exceeded 100 miles per hour. The previous speed will be higher.

Calculated according to rectal temperature, the time of death of the deceased was 2:23 in the morning. In the report given, Forensic Doctor Liu asked me to write between 2:00 and 3:00. During this time period, driving at such a high speed, the key point is that I found that there is still a The brake marks from cars parallel to this one, I guess someone is racing illegally? "

Both Zhao Xinli and Xu Dayuan looked at Zhou Ning. After this sentence, the two of them fell silent. Zhou Ning was a little nervous for a while. Could it be that his guess was outrageous?
At this moment, Xu Dayuan kicked Zhao Xinli with anger on his face.

"Biaozi, I'm going to check the identity of the deceased, and I asked you to lead a team here to find traces of the scene, you've seen the fart!"

Zhou Ning was taken aback for a moment, and didn't dare to speak directly.

"Forensic doctor Xiao Zhou, hurry up and take me to see the brake marks you found."

Zhou Ning led them over, glanced at Zhao Xinli apologetically, and found that this kid didn't know what embarrassment was, and followed with interest, still smiling.

"Leader, don't worry, I just saw that the traces here are somewhat similar, but compared with the brake traces with blood, this place is much shallower, and the braking distance is also longer."

Xu Dayuan waved his hand.

"Don't make up for them, quickly check, how much is this data, can you know the model?"

Zhao Xinli was already eager to try on one side, glanced at the three data, and quickly browsed it on the phone. After looking through it for a long time, there was no text, and Xu Dayuan had already raised his leg.

Zhao Xinli dodged to the side, his fingers seemed to be zooming in on the picture, and then he let out an exclamation.

"I'll go, really, someone in our county drives such an expensive car?"

PS:
【1】Pyrolysis gas chromatography-mass spectrometry:
In traffic accident cases, the scraping and bumping of vehicle tires and other objects, and the sliding friction between brakes and the ground will cause rubber particles to transfer to the contact object or leave on the ground to form brake marks.Inspection of these rubber particles can provide evidence for restoring the truth and identifying the vehicle involved in the accident.

Automobile tires use natural rubber (NR), butadiene rubber (BR) and styrene-butadiene rubber (SBR) alone or in combination, and add organic or inorganic additives such as vulcanizing agents, accelerators, anti-aging agents, and fillers.It can accurately judge the rubber type according to the characteristic cracking products, and the combined application with the SEM-EDX method can conduct a comprehensive analysis of the organic components and inorganic elements in the rubber. In recent years, it has become an important means of rubber inspection and identification.

(End of this chapter)