The office space is limited, and in the face of Zhao Heng's strange poisoning death, the only thing Gu Chen can think of is the modus operandi, and in terms of identification, it is naturally completed by the technical department of the Municipal Bureau.

If the modus operandi cannot be found, the evidence of the murderer's guilt cannot be determined.

"Gu Chen, say whatever you want, there are no outsiders here. Officer Wang's suppressed mood just now seemed to be relieved because of this.

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

"Wait. Gu Chen didn't answer immediately, but handed over the account book information sent by Zeng Ke to Forensic Doctor Liu: "Forensic Doctor Liu, can you help me check this account book?"

"Check the account books?" Comrade Liu, a senior forensic doctor, was slightly puzzled for a while: "Gu Chen, I can't read the account books." ”

"You don't have to read it. Gu Chen smiled lightly: "I mean, you just need to help me check if it contains highly toxic substances?"

"I see. Forensic Doctor Liu felt that he had deviated a little from Gu Chen's thoughts, and said embarrassedly: "This is easy to say." ”

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

While Forensic Doctor Liu 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 bring the information next to Zhao Heng?"

"Is this the book?" Lu Weiwei hesitated a little, she was still not sure whether Gu Chen's action was effective, but she still handed over the account book.

Gu Chen opened the information book and soaked the footers in the water one by one.

"There's a residue on this, right?" Officer Wang asked, gritting his teeth, feeling like he was suddenly marginalized.

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

Any suspicion needs to be verified before it 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 there is to it.

To say that Zhao Heng was able to die of poisoning soon after the three of them left, the only possible clue is that he had been exposed to some colorless and odorless substances, resulting in poisoning and death.

Seeing Gu Chen soaking the footer of the information in clear water, Officer Wang at this time no longer needed Gu Chen to explain, and probably guessed the reason why Gu Chen did this.

"Gu Chen. Officer Wang squeezed to his side, his eyes fixed on the data book, to prevent himself from being marginalized.

Gu Chen moved a small step slightly, gave up a position, and asked, "Is there something wrong with Senior Brother Wang?"

Then he continued to operate in earnest.

Seeing that Gu Chen was so serious, Officer Wang couldn't help but say, "Do you think that Zhao Heng's poisoning death was because he touched the footer of the information with his hand?"

"Senior Brother Wang, you finally guessed. Gu Chen smiled lightly, and then threw the soaked information book aside.

"I think that this should be coated with a colorless and odorless highly toxic substance, which is not the same as the bottle of poison we found next to Zhao Heng before. ”

"I know, you mean that the bottle may be a trick, and what really caused Zhao Heng's poisoning and death may be the highly toxic substances remaining on the ledger materials, and Zhao Heng's habit of licking his hands with his tongue caused him to come into contact with the highly toxic substances in the footer of the ledger, right?"

According to Gu Chen's prompts, Lu Weiwei quickly followed up with the train of thought.

Gu Chen nodded: "Senior Sister Lu is so smart. ”

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

Subsequently, Gu Chen handed over the remaining clear water to Forensic Doctor Liu.

The forensic assistant looked stunned, and couldn't help but say, "Gu Chen, you're robbing me of my job." ”

Clearly, forensic assistants also feel marginalized.

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

However, for Jiangnan City, which has a population of nearly 10 million, the scale of the technical department is larger than that of ordinary counties and cities, and there are more things to be exposed to.

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

Pouting, Forensic Doctor Liu shouted at the forensic assistant, "Xiao Wu." ”

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

"Be positive in doing things, don't wait for things to do, take the initiative to find work to do, in my opinion, you lack Gu Chen's enthusiasm. ”

I originally thought that I would come over and have something to do, but I didn't expect it to be a training, and the forensic assistant was also drunk.

Forensic Doctor Liu has always disliked lazy assistants, especially the work he does, and as a result, he was robbed by other departments.

"Yes, master. The forensic assistant nodded, then ...... He stared at Gu Chen fiercely.

Gu Chen's operation is very simple, a simple chemical reaction method, using the solution to have a chemical reaction with the detected substance, by observing the reaction, the color and state of the reactant to determine whether there is a certain substance.

This kind of basic operation can be understood by ordinary professionals, but Gu Chen is a probationary police officer and has no intersection with the forensic science department at all.

Being able to understand these is already precious.

Forensic Doctor Liu even came up with the idea of replacing his apprentice.

"Young people should learn more skills. After finishing the tools in his hand, Forensic Doctor Liu couldn't help but ask again: "Gu Chen, have you learned this?"

"Nope. Gu Chen shook his head.

"Gu Chen usually goes to the library after work, and he probably saw it there. Lu Weiwei, who has been silently paying attention to the little junior brother, said in passing.

"It's nice to know that. "Forensic Doctor Liu is also operating at the same time, by the way.

"Our forensic testing generally has a chemical reaction method, which has the advantages of simple operation, rapidity, and less time and place restrictions, but the sensitivity is not high, and the specificity is not strong, and it is generally only used as a pre-experiment to narrow the scope of poison analysis. ”

Gu Chen listened very seriously: "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. Forensic Doctor Liu nodded: "For example, according to the Prussian blue reaction, to determine whether the sample contains cyanide, according to the Grignard reaction to determine whether there is nitrite in the sample, these are all the same truth." ”

"But chromatography is more popular now. Gu Chen said again coldly, his mind is full of knowledge now, and it is indeed a bit difficult for him to endure it.

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

Gu Chen hesitated for a moment and said with a light smile: "No. 1 11μm is the most frequently used in daily filtration, with a medium-retention flow rate, which is very widely used in laboratory applications, clarifying liquids, and is typically used for the quantitative analysis and separation of precipitates, such as lead sulfate, calcium oxalate and calcium carbonate. ”

Forensic Doctor Liu snorted and said indifferently: "You're right, but are you sure you use this number?"

Although what Gu Chen said was quite reasonable and detailed, it seems that now he only understands a little bit of skin.

But that's all, in Forensic Doctor Liu's heart, it is already very rare.

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

Forensic Doctor Liu was stunned: "You go on." ”

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

Gu Chen's words stunned everyone present, and the forensic assistant standing on the side suddenly hated him even more.