I am a super cop

Chapter 820
In the lecture hall, Lu Weiwei's performance really shines.

Everyone knew that Lu Weiwei, like Police Officer Wang, was from the criminal investigation team of Furong Branch of Jiangnan City.

For forensic doctors, both of them are laymen, but the instructor Zhang Hui's question did not make it difficult for them.

This disappointed many forensic doctors who wanted to see a joke.

Zhang Hui was stunned for a moment, and then recovered from the astonishment in his eyes: "Very...very good, please sit down."

Lu Weiwei nodded, and after sitting down, she blinked her right eye at Gu Chen.

However, there was a sudden whisper at the scene.

"The police at the Furong Sub-bureau in Jiangnan City are really good."

"Yeah, two questions in a row, he blurted out, which shows that his knowledge reserve is not ordinary."

"Damn, are all the students sent by Jiangnan City this time? It's no wonder they can come to participate in the training."

……

It was also when everyone bowed their heads and whispered, and the bald instructor Zhang Hui coughed twice, the scene gradually quieted down.

"The female student said very well just now, yes, these characteristics make diatoms have a wide range of applications in red tide detection, aquaculture, water quality monitoring, resource investigation, paleoenvironmental analysis, oil exploration, forensic identification and other fields. "

"And diatoms belong to the diatom class of diatoms in the algae. They are a kind of phytoplankton. Where there is water stagnation on the earth, it is as small as a small puddle formed by rainwater accumulation, as large as 71% of the earth's surface. Diatoms can be found almost everywhere in the ocean.”

"There are also some diatoms, which grow as terrestrial types on moist soil surfaces and exposed surfaces of other objects, and some of them float in the air."

Looking up at Gu Chen's direction, Zhang Hui found that Police Officer Wang and Lu Weiwei were giving Gu Chen a high-five to celebrate.

Immediately, the slack brows were furrowed again.

Zhang Hui coughed twice and said absent-mindedly: "We all know that there are more than 16000 species of diatoms in the world, and the body length is generally 1-200 μm. Diatoms are sensitive to water quality. Different water environments have different diatom communities."

"The most obvious feature is that the cell wall is highly silicified except for a few species, forming two transparent shells, the upper and the lower, and the rings of the shell are combined to form a siliceous cell wall, which is hard and stable, not easy to be damaged, and not subject to corruption and death."

"Even if concentrated sulfuric acid and concentrated nitric acid are boiled, it is difficult to destroy its texture characteristics, so based on these characteristics, diatoms play a significant role in forensic detection."

The PPT picture quickly turned over and entered the next stage of blue background copywriting.

Zhang Hui stood up suddenly, went to the whiteboard of the podium, and wrote some copywriting materials on the whiteboard.

Glancing back at the crowd, Zhang Hui tapped the whiteboard with the back of his hand to draw key points.

"Pay attention to this. Everyone remembers this. Due to the active breathing of those who entered the water during their lifetime, diatoms can be inhaled into the alveoli along with the drowning, enter the blood circulation, and distribute to various tissues and organs."

"And through the qualitative and quantitative analysis and comparison of the organ tissue and diatoms in the water, not only can the cause of death be directly determined, but also help to infer the place of drowning."

When the forensic science students heard the words, they all copied them into their transcripts one after another.

Everyone may be aware of these, but after all, it is the first time for many people to understand the characteristics of diatoms.

Therefore, whether it is a forensic doctor who knows or does not know, everyone bows their heads and takes notes.

The painting style on the scene was very harmonious, but only Gu Chen in the corner of the back row was still unmoved.

But it's not that Gu Chen doesn't want to take notes, it's just because of this information, Gu Chen has read it in the city library a few months ago.

What the instructor Zhang Hui said just now, Gu Chen has already used his professional memory to perfectly record it in his mind.

Officer Wang and Lu Weiwei's answers just now are the best embodiment of verifying their memories.

Zhang Hui felt that Gu Chen was a bit disrespectful.

From the beginning of the lecture to the present, Gu Chen hardly writes, which is a very unusual existence in the dogmatic training system.

Zhang Hui frowned, and continued: "Next, we will talk about a long-standing problem, that is, the identification of the cause of death of the corpse in the water."

Seeing Gu Chen's indifferent face, Zhang Hui curled his lips and smiled: "I need a teaching assistant to help me write on the whiteboard. I don't know...Which student is willing?"

The scene was quiet for a few seconds, and several students in the front row raised their right hands one after another.

However, after Zhang Hui pretended to observe, he suddenly pointed at Gu Chen and said, "Just...that student, yes, it's you, sitting in the back row next to the female student who answered the question just now."

"Me?" Gu Chen was called on suddenly and stood up to confirm.

"Yes, it's you." Instructor Zhang Hui reconfirmed.

Only then did Gu Chen walk out of his seat, and walked up the stairs to the podium under the eyes of everyone.

Zhang Hui handed the oil-based pen to Gu Chen, and said with a smile, "Student, just stand here and help me write on the whiteboard."

"No problem." Gu Chen nodded slightly, took the oil-based pen, and went directly to the whiteboard.

Only then did Zhang Hui let out a long sigh of relief, thinking that the little comrade was standing on the podium listening to his lecture, so he should be able to concentrate, right?
Thinking about it is also for his own good...

So Zhang Hui sat back in his seat and continued to give lectures.

"We just talked about a long-standing and difficult problem, that is, the identification of the cause of death of the corpse in the water."

"Tuk tuk tuk..."

As soon as Zhang Hui finished speaking, Gu Chen had already written the six characters "Cause of Death Identification" on the top of the whiteboard.

Zhang Hui took a peek and was quite satisfied, so he continued: "Everyone should know that drowning is a death method caused by suffocation caused by liquid blocking the respiratory tract and alveoli, hindering gas exchange, lack of oxygen in the body, and carbon dioxide retention."

As soon as the voice fell, Gu Chen had already listed several key points, almost at the same time.

Zhang Hui didn't care, but continued: "According to the "Global Report on Drowning" released by the World Health Organization in 2004, 34.2 people drowned every year in the world, with an average of 42 deaths per hour."

"According to statistics, about 6 people drown in our country every year. Drowning is the third cause of accidental death in our country and the first cause of death for children under 3 years old."

After seeing himself finished speaking, Gu Chen suddenly stopped writing.

Zhang Hui glanced at him and reminded, "Write it down."

"Instructor, your data doesn't seem to be very accurate." Gu Chen didn't intend to continue, but instead questioned Zhang Hui.

The scene suddenly became lively...

Everyone didn't expect that Gu Chen would question instructor Zhang Hui's data in person. In everyone's opinion, is Gu Chen too floating?

For a while, everyone in the audience was talking about it.

Seeing this, Zhang Hui asked Gu Chen angrily, "This student, what's your name?"

"Gu Chen." Gu Chen said.

"Which unit are you from?" Zhang Hui asked again.

"The third criminal investigation group of the Furong Branch of Jiangnan City." Gu Chen said.

Zhang Hui suddenly snorted and said, "I said Gu Chen, I've seen your file, you shouldn't be a forensic doctor, right?"

Gu Chen nodded.

"Then why do you question that my data is wrong?" Zhang Hui asked again.

Gu Chen did not speak, but changed the "Global Report on Drowning" released by the World Health Organization in 2004 to 2014.

Subsequently, the data that 34.2 people drowned every year in the world was revised to 37.2.

Zhang Hui was stunned suddenly. He quickly looked down at the documents in his hand, but was suddenly startled.

There is nothing wrong with the data modified by Gu Chen, but there is a data error in the data on hand.

It is true that the statistical report is from 2014, but it is 2004 on my own data, a difference of 10 years.

In 2014, the number of drownings was 37.2, but the data on hand was 34.2, a difference of 3.

Zhang Hui was a little surprised...

"How did Gu Chen know this? He actually knew that my data was wrong? Isn't this incredible?"

Zhang Hui was terrified, but he picked up the materials in his hand, pointed to the assistant teacher Yang Ting and said, "Xiao Yang, you sorted out these materials, right?"

"Yes." Yang Ting nodded silently: "It was sorted out according to your manuscript."

"Look at you, you are careless." Zhang Hui threw the A4 paper documents on the table, and said angrily: "You typed these data wrong."

"Did you make a big mistake?" Yang Ting hurriedly checked herself when she heard the words: "No way? Why did you make a mistake?"

Zhang Hui picked up the manuscript, tapped his fingers and said: "On my manuscript, it is clearly stated that according to the "Global Report on Drowning" released by the World Health Organization in 2014, 37.2 people drown every year in the world, an average of 42 deaths per hour. people."

"And look at what you have organized? 2014 has become 2004, and 37.2 people have become 34.2 people. Are you too careless?"

"Really?" Yang Ting panicked suddenly.

She hurriedly took out the manuscript that Zhang Hui had given her from the document bag, and opened a few pages for verification.

After a while, Yang Ting was dumbfounded: "It's really a mistake."

Glancing at Zhang Hui, Yang Ting bowed her head and apologized, "I'm sorry, maybe I typed too fast and didn't check clearly. I'm really sorry."

"Okay, be more careful next time." Zhang Hui also waved his hand, telling Yang Ting to sit down first, and then said:

"Our work must be rigorous. This time it is just a report. Next time, if there is a data error in the laboratory operation stage, it will not be serious. It is very likely that everyone's hard work will be in vain."

"Yes yes yes, my fault." Yang Ting also had the courage to bear the mistake, but she didn't quite understand: "But... how did Gu Chen know that my data was wrong? Didn't he read this manuscript? "

"Yes, how did Gu Chen know?"

There are still many people who have doubts like Yang Ting.

Can this kind of data be known?My heart said, you shouldn't even memorize the Xinhua dictionary, right?
Zhang Hui was also stunned. Yang Ting's question just now made him feel puzzled.

There was an error in his own data, but Gu Chen was able to find the problem in the first place.

More importantly, he was able to accurately express the real statistical data, which shows that Gu Chen also understands the report.

Zhang Hui looked Gu Chen up and down, and then asked him: "Gu Chen, how do you know?"

"I have read the "Global Report on Drowning" released by the WHO in 2014." Gu Chen said.

"Have you seen it?" Zhang Hui was dubious, and continued to ask him: "Have you even touched this?"

"A few months ago, I saw it in our Jiangnan City Library." Gu Chen said.

Zhang Hui squeezed his chin, but he couldn't believe it: "But... It's been a few months, and you can even remember these data now?"

"Yes, but I also recall that the WHO estimated that the actual number could be twice as high."

"That's very good." Seeing that Gu Chen could tell the data accurately, Zhang Hui's eyes on Gu Chen changed.

It feels like this young man has a superb memory, which is far superior to others.

After blushing for a while, Zhang Hui picked up the writing pen on the table, corrected the data, and then said:

"After all, due to the dense network of rivers, lakes and seawater in our country, the number of drowning corpses that need to be identified every year is huge."

"Among the drowned corpses found in rivers, lakes and seas, most of them belong to the accidental death of the drowning person, but there are also cases of suicide or homicide among the drowning person, and it is not ruled out that the dead body is thrown into the water after death and faked as accidental drowning. .”

Zhang Hui glanced at Yang Ting, who immediately switched slides.

At this moment, a picture of a city river is displayed on the screen.

One side of the river in the city was cordoned off, and beside the river was a blue tent temporarily erected by the police.

Zhang Hui coughed twice, and continued: "In recent years, drowning deaths have occurred from time to time, but detection is also very difficult."

"It's okay to have witnesses, and the cause of death can be determined, but for those drowning victims who have no witnesses, detection technology needs to be used."

"As for corpses in fresh water, drowning identification can be carried out through the typical signs of drowning such as fungal foam in the mouth and nose, water emphysema, and sediment in the respiratory tract."

"However, when more than 80% of the corpses in the water were found, they showed a high degree of corruption, and all signs of drowning disappeared."

"In addition, autopsy and histological examination, whether there are specific pathological changes related to drowning, and the identification of the cause of death has become a world-recognized problem, and the cause of death is the key to the qualitative nature of the case."

After a pause, Zhang Hui saw that Gu Chen had already written the main points, so he couldn't help but say, "This involves the handling of the police."

"Because the cause of death is unknown, the case cannot be determined, which can easily lead to dissatisfaction among family members, as well as public speculation and media hype."

"That's why our forensic doctors must conduct accurate tests to find out the cause of death and give the family a satisfactory explanation, otherwise we will cause big trouble."

Seeing Gu Chen's tacit cooperation on the whiteboard, Zhang Hui's attitude improved a lot, and he casually asked Gu Chen, "Gu Chen, do you know any famous examples?"

Gu Chen stopped writing, and after thinking about it carefully, he said: "The 'Lan Ke'er incident' that happened in the United States in February 2013 is a typical example."

"That's right." Zhang Hui nodded slightly, and said to the audience: "So, if the investigation is not thorough, it will cause many social problems. This requires our work to be rigorous, so this puts forward higher requirements for our forensic testing. "

Glancing at Gu Chen, Zhang Hui said again: "Gu Chen, do you know what experiments we forensic scientists have done to solve the problem of identifying the cause of death of corpses in water?"

The scene was suddenly quiet, and everyone was sweating for Gu Chen.

I thought to myself that Zhang Hui, the instructor, is relying on Gu Chen?

You can't pick just one wool, can you?Don't you give others a chance?
In fact, many forensic doctors in the audience also knew something, but Zhang Hui only gave Gu Chen the opportunity to answer, and also wanted to test the true level of this young man.

After Gu Chen meditated briefly for a few seconds, the data flow in his brain began to tumbling rapidly, and soon appeared in his mind.

Gu Chen raised his head and said, "Forensic scientists have successively studied methods such as diatom test, blood biochemical test, foreign body element test, plant pollen spore test, and chlorophyll-a test."

"However, except for diatom testing, other methods are limited to experimental research and have not been applied in forensic practice."

"That's very good." Zhang Hui was satisfied with Gu Chen's answer, so he smiled and said, "So diatom testing, as I said, is the 'gold standard' for drowning diagnosis."

"As for how to judge whether to enter the water before death or throw the body into the water after death, diatom detection has always been the most commonly used method in forensic practice."

"But there are also doubts and disputes." Gu Chen directly refuted it back.

Zhang Hui frowned, a little unhappy, thinking that Gu Chen is here to smash the scene, right?

But what Gu Chen said was correct. Just as Zhang Hui was about to speak, another first-class police inspector sitting next to him said, "Gu Chen, you said that there are also doubts and disputes about diatom testing. Why?"

"Because at present, most forensic doctors at home and abroad use optical microscopes to detect diatoms in the organs and tissues of drowning victims."

"Although the method of diatom detection technology cannot directly determine the exact cause of death of drowning victims, the comparison of the type and quantity of water samples at the drowning place of drowning deaths can help determine the death location of drowning deaths. positive effect."

Gu Chen connected seamlessly, expressed his opinion, and then said:

"Although diatom detection has been used in the diagnosis of drowning for more than 100 years, the value of diatom detection has always been controversial, mainly because there are many diatom detection techniques and methods used by the forensic circles in the world. .”

Speaking of this, Gu Chen directly picked up the oil-based pen, wrote on the whiteboard and said: "The main method is to use the diatom enrichment method and diatom observation method after the sample is extracted and digested."

Looking back at the audience, Gu Chen stepped forward and explained to everyone: "Because diatoms are widely distributed in nature, they are commonly found in fresh water, sea water, air and food, especially vegetables."

"Combined with the passive pollution of corpses in the water, atypical drowning and corpses entering the water after death, corpses that died in some waters lacking diatoms, and the pollution problem of the experiment itself, in fact, including many influencing factors such as containers and reagents, diatoms The role of the test in diagnosing drowning has been controversial.”

When everyone heard the words, they also nodded frequently, as if what Gu Chen said made sense.

However, Gu Chen's old problem happened again, and he instantly took this place as the scene of the crime, and explained to everyone involuntarily: "Actually, domestic and foreign diatom testing laboratories have always used strong acid boiling to digest, centrifuge enrichment, and light microscope observation. technology."

"These traditional technologies actually have significant defects. In addition to the above-mentioned pollution problems, they are also manifested in...the low recovery rate of diatoms extracted from organ samples, poor detection sensitivity, and high false negative rate."

"The diatoms are small and low in content, and are limited by the magnification of the light microscope, so they are prone to missed and false detections."

"Cough cough." Seeing that Gu Chen took away his right to speak, instructor Zhang Hui complained a little, and coughed twice as a reminder.

However, Gu Chen didn't pay attention at all, snapped his fingers and continued: "The diatom test needs to identify the species of the diatom to be tested."

"However, forensic inspectors usually lack the professional knowledge of diatom taxonomy and misjudge other foreign body attributes as diatoms, which to a certain extent restricts the application of diatom testing in the diagnosis of drowning."

"Okay...Okay." Seeing that Gu Chen was eloquent and didn't intend to stop, the instructor Zhang Hui was a little flustered, and hurriedly interrupted: "Gu Chen, you'd better sit back."

……

(End of this chapter)