I am a super cop

Chapter 39 Detection method (recommendation ticket please)
The office space is limited. Faced with Zhao Heng's strange poisoning death, the only thing Gu Chen can think of is the modus operandi. As for the appraisal, the Technical Section of the Municipal Bureau is naturally responsible for the completion.

If the modus operandi cannot be found out, there will be no evidence of the murderer.

"Gu Chen, you can say whatever comes to your mind, there are no outsiders here." Police Officer Wang seemed to be relieved of his suppressed mood just now.

He knew that Gu Chen seemed to have made some new discoveries.

"Wait first." Gu Chen didn't answer right away, but handed the ledger information sent by Zeng Ke to Forensic Liu: "Forensic Liu, can you check this ledger for me?"

"Check the account book?" Comrade Liu, a senior forensic doctor, was a little confused for a moment: "Gu Chen, I can't read the account book."

"You don't need to understand." Gu Chendan said with a smile: "I mean, you just need to check for me, does it contain any highly toxic substances?"

"So that's how it is." Liu Fayi felt that he was a bit deviated from Gu Chen's thoughts, and said embarrassingly: "It's easy to say."

Then he called the forensic assistant: "Xiao Wu, help me get the toolbox."

While Liu Fayi was preparing, Gu Chen was not idle. He took out a glass of water from the water dispenser, put it on the table and said, "Senior Sister Lu, can you help me get the brochure beside Zhao Heng?"

"Is this the book?" Lu Weiwei hesitated, she was still not sure whether Gu Chen's actions would be effective, but she still handed over the book.

Gu Chen opened the textbook and soaked the footers of the pages one by one in water.

"Is there any residual substance on it?" Police Officer Wang gritted his teeth and asked, feeling that he was suddenly marginalized.

"Maybe this substance is colorless and odorless, so we can only try it first." Gu Chen replied lightly.

Any doubts need to be verified before they can be called evidence.

What Gu Chen has to do now is to verify whether his reasoning just now is correct.

You know, in a closed office, that's all the people who come in and out.

To say that Zhao Heng was able to die of poisoning shortly after the three of them left, the only possible clue was that he had been in contact with some colorless and odorless substances, which led to his death from poisoning.

Seeing Gu Chen soaking the footer of the document in clear water, Police Officer Wang at this time probably guessed the reason for Gu Chen's doing so without Gu Chen's explanation.

"Gu Chen." Officer Wang squeezed to his side, staring at the information book to prevent himself from being marginalized.

Gu Chen moved a small step, gave way to a position, and asked, "Senior Brother Wang, is there something wrong?"

Then continue to operate seriously.

Officer Wang saw Gu Chen's seriousness, so he couldn't help but say, "Do you think that Zhao Heng died of poisoning because he touched the footer of the document?"

"Senior Brother Wang, you finally guessed it." Gu Chendan laughed, and then threw the soaked information book aside.

"I think it should be coated with a colorless, odorless and highly poisonous substance, which is completely different from the bottle of poison we found beside Zhao Heng earlier."

"I see. You're saying that the bottle might be a blindfold, and what really caused Zhao Heng's death from poisoning might be the highly toxic substance left on the ledger data, and Zhao Heng's habit of licking his hands with his tongue led him to come into contact with it. A highly toxic substance in the footer of the ledger, right?"

According to Gu Chen's prompt, Lu Weiwei quickly followed her train of thought.

Gu Chen nodded: "Senior Sister Lu is really smart."

Being praised by this, Lu Weiwei felt that she was about to fly, and her heart was warm.

Afterwards, Gu Chen handed over the remaining clear water to Liu Fayi.

The forensic assistant looked astonished, and said involuntarily, "Gu Chen, you are stealing my job."

Clearly, forensic assistants also feel marginalized.

There is a division of labor in the technical department, which is generally composed of several senior forensic doctors, and assistants are allowed.

But for Jiangnan City, which has a population of nearly [-] million, the scale of the technical department is larger than that of ordinary counties and cities, and there are more things in contact with.

Liu Forensic Doctor currently has two forensic assistants on hand to form a working group responsible for the daily work of the police stations in all districts of the city.

Curling his lips, Forensic Doctor Liu called out to the assistant forensic doctor, "Xiao Wu."

"Master, I'm here." The forensic assistant hurried up.

"Be proactive in doing things, don't wait for things to be done, and take the initiative to find work. In my opinion, you lack the enthusiasm of Gu Chen."

Originally, I thought I would come here to do something, but I didn't expect to be trained, and the forensic assistant was also drunk.

Forensic Liu has always disliked lazy assistants, especially his own work, which ended up being snatched away by other departments.

"Yes, master." The forensic assistant nodded, and then... he stared fiercely at Gu Chen again.

Gu Chen's operation is very simple, a simple chemical reaction method, using the solution to react chemically with the detected substance, and by observing the reaction, the color and state of the reactant can be used to judge whether there is a certain substance.

This kind of basic operation can be understood by ordinary professionals, but Gu Chen is a trainee policeman, and has nothing to do with forensic science.

Knowing this is already invaluable.

Liu Fayi even had the idea of ​​replacing his apprentice.

"Young people, you should learn more skills." Liu Forensic, who finished packing up the tools in his hands, couldn't help but ask again: "Gu Chen, have you learned these?"

"No." Gu Chen shook his head.

"Gu Chen usually goes to the library after get off work, so I probably saw it there." Lu Weiwei, who had been silently paying attention to the younger brother, said something casually.

"It's good to know these things." Forensic Liu was also doing the operation while talking about it by the way.

"Our forensic testing generally uses chemical reaction methods, which have the advantages of simple operation, rapidity, and less time and place restrictions, but the sensitivity is not high and the specificity is not strong. Generally, it is only used as a preliminary experiment to narrow the scope of toxicological analysis. "

Gu Chen listened carefully: "It seems that the chemical reaction method is rarely used now, but in some cases, it can be used for confirmatory analysis."

"That's right." Liu Forensic Doctor nodded: "For example, according to the Prussian blue reaction, it can be judged whether the tested object contains cyanide, and according to whether the Grignard reaction appears red, it can be judged whether there is nitrite in the test solution. Makes sense."

"But chromatography is more popular now." Gu Chen said again out of the blue, his mind is full of knowledge now, it is really difficult for him to hold back.

"Chromatography is a method of separation and analysis." Liu Forensic took out the domestic Xinhua filter paper from the toolbox, and asked casually, "Do you know which one you use?"

Gu Chen hesitated for a moment, and said with a light smile: "No. 1 11μm is the most frequently used in daily filtration. The flow rate with medium retention is very widely used in laboratory applications to clarify liquids, and is typically used for sediments. Quantitative analysis of separations such as lead sulfate, calcium oxalate and calcium carbonate."

Liu Fayi snorted and said calmly: "You are right, but are you sure you use this number?"

Although what Gu Chen said is quite reasonable and detailed, but now it seems that he only understands the surface.

But these are already very rare in Liu Fayi's mind.

"No." Gu Chen shook his head and smiled, "If it were me, I would choose No. 5, which is 2.5μm."

Fayi Liu was stunned: "Go on."

"Because this is the most efficient qualitative filter paper." Gu Chen paused, and thought for a while: "It can be used to collect small particles, the flow rate is slow, and it is suitable for chemical analysis, clarification of suspended matter and water analysis."

When Gu Chen said this, everyone present was dumbfounded, and the forensic assistant standing aside immediately hated him even more.

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(End of this chapter)