Under the combined effect of genetics and environment, the repetition rate of fingerprints is extremely small, only about 1 in 15 billion, and it has a very important exclusivity in the criminal signature. Fingerprint extraction is a very common forensic technical means in the process of case investigation, and almost every case is involved in forensic work.

When Wei Chongyu took Mu Yuan to the laboratory, Liu Yihang was standing at the experimental table with a sad face. In the identification work, the signature analysis of the evidence is generally carried out in the most gentle and safe way, but because some of the evidence itself is very fragile, the damage to the evidence also occurs from time to time. However, Liu Yihang couldn't accept this reality, as an old technician, he made a mistake in such a trivial matter as extracting fingerprints, and he was really a little embarrassed.

"Last night, I mainly carried out the relevant identification work on the skeleton!" Liu Yihang explained, "Because this anti-evil charm is the only evidence found in this case, I decided to do it myself this morning." ”

Liu Yihang first made a simple measurement and analysis of the size and material of the spirit rune, but he obtained very little. There is nothing special about the material of this talisman, it is just ordinary yellow table paper, which can be seen everywhere in the market. Subsequently, he decided to try fingerprint extraction on paper, although this spirit rune has been smeared in the soil for ten years, and after being soaked and corroded by corpse fluid, the possibility of extracting fingerprints is very small, but Liu Yihang does not want to give up this test. Because this rune can be stored in such an extreme environment for ten years without damage, this ability is incredible, so it may not be a fantasy to extract a fingerprint from it.

"I configured the fumigation reagent and hung the spirit rune, but as soon as I turned around, this spirit rune burned by itself!" Liu Yihang said in annoyance, "At that speed, I can't even rescue it!" ”

Mu Yuan looked at the extraction equipment on the experimental table, which was a transparent plastic box, which had been smoked and blackened at this time. The box is about 50 centimeters long and 1 meter high, and a thin metal rod is placed in the center of the top, at this time, the clip on the thin pole also holds a piece of paper ashes, and the bottom of the box is also scattered with dust and debris.

"Chemical extraction methods?" Makihara muttered to himself.

Because the body surface is covered with secretions such as oil and sweat, fingerprints can be formed on the surface of other objects when they come into contact with them. For the appearance of fingerprints, there are two ways: chemical extraction and physical extraction. What often appears in TV and movies is the logistics method, which uses a brush dipped in a small amount of powder and scrapes the fingerprint attachment to make the fingerprint visible. However, the physical display method has high requirements for the material and time of the evidence. Chemical manifestation methods are also often used when dealing with exhibits made of special materials.

Liu Yihang used the ninhydrin method in chemical methods, which is also mostly used to show sweat stains on paper. α amino acids and ninhydrin are heated together in a weakly acidic solution, and after the reaction, they are decarboxylated by water loss to form aminoninhydrinhydrone, and then react with hydrated ninhydrin to form purple-red, and finally become a blue substance, thus showing the texture of handprints.

"Do you know anything about these technical qualifications?" Liu Yihang heard Mu Yuan's muttering and asked in surprise.

"I don't know!" Makihara smiled, "I'm a fan of American dramas, there are a lot of crime identification plots in the American drama "Crime Scene Investigation", and there are also a lot of explanations and elaborations on the principles of some identification techniques, and I have watched a lot, so I also know some." ”

Liu Yihang nodded with understanding.

"Liu Ke, have you ever extracted cinnabar from this spirit rune?" Makihara thought for a moment and asked.

"Yes!" Liu Yihang nodded and said, "I used an extraction cotton swab to dilute the surface of the spirit rune cinnabar ink, and then extracted a few samples, which have been used to analyze the ingredients!" ”

"Oh, that's no wonder!" Makihara nodded and said, "I think that's where the problem arises!" ”

"This can't be!" Liu Yihang frowned and said, "The liquid on the cotton swab is a standard extract, and there are no flammable substances, how can it be possible to ignite the spirit rune?" ”

"It is said that when the real talisman is made, it is infused with a mysterious power, which we can understand as a magnetic field, which is in a relatively stable state." Makihara explained, "And once an external force changes this magnetic field, the talisman loses its mana, or destroys itself. ”

"This is also what you see from American dramas?" Wei Chongyu asked.

"Haha!" Mu Yuan smiled and said, "No, I want to watch it, but there are no such things in American dramas!" ”

"This is too mysterious, there is no scientific basis at all!" Liu Yihang said.

"Science is not static, it is constantly evolving, even subversive!" Mu Yuan smiled and said, "In my opinion, Liu Ke, your sentence 'completely without scientific basis' itself has no scientific basis, and if you only use the scientific principles you have mastered to explain everything, it is like a blind man touching an elephant." For example, if a primary school student is asked to solve a junior high school or high school problem using elementary school mathematics, even if he is told the answer, he will probably say that this is completely unscientific. ”

Liu Yihang and Wei Chongyu glanced at each other, but neither of them spoke.

"I'm sorry, I seem to be off topic!" Mu Yuan scratched his head, made an embarrassed look, and said, "My way of thinking has always been weird, too divergent. The conclusion just now is just my guess! ”

"Well, it's very divergent!" Liu Yihang nodded and said, "But it seems to make sense, but I still don't know how to write this report!" ”

"Liu Ke, can you give me a few photos of the spirit runes?" Makihara asked.

"This ...... It seems a bit out of line with the charter! Liu Yihang was stunned for a moment, and then said in embarrassment, "At present, the case is still in the process of being solved, and any evidence information cannot be leaked!" ”

Mu Yuan looked at Wei Chongyu and hoped that he could help say a few good words, but Wei Chongyu shook his head slightly, because he had no choice. It is within the scope of the law to bring Makihara over to "touch" the exhibits, but if Makihara is allowed to take the photographs of the exhibits, it will be beyond the regulations. In the process of solving a case, sometimes in order to collect more clues and information, some evidence will be released to the public, but of course, this case is not within this scope.

"Then if I wait for the case to be solved, can I apply?" Makihara asked unrelentingly.

"Oh, this should be fine!" Liu Yihang said, "As long as this case is not classified as a confidential case, the subsequent case files can be made public!" ”

"Okay, thank you!" Mu Yuan nodded, but he was bitter in his heart, and when the case was solved, when would he wait.

Leaving the Criminal Investigation Technology Department, Wei Chongyu invited Mu Yuan to sit in the office, but Mu Yuan refused on the grounds that he wanted to attend class, he actually didn't want to see Meng Yan, the current state of that Tyrannosaurus Flower was extremely close to the Tyrannosaurus Rex, since there was nothing to discuss with Wei Chongyu now, he had better go around first.

After leaving the Public Security Bureau, Mu Yuan's mind was still on the town charm, thinking about how to get the photo as soon as possible. At this moment, Mu Yuan's phone rang, and when he took out his mobile phone, he saw that it was Yin Hao calling.

"Mouse, what's wrong?" Makihara asked.

"Congratulations!" Yin Hao said excitedly, "It's finally time for business!" We're opening! ”

"Business? Opened? Mu Yuan was confused and asked, "Mouse, you have a virus in your brain!" Where do I have any business? ”

"Mu Yuan, your words are the biggest insult to me!" The mouse said dissatisfiedly, "I'm talking about the website, huanti point cn!" ”

"What did you find?" Makihara asked.

"Someone uploaded some photos this morning and sent out a message asking for help!" Yin Hao said, "It's not clear on the phone, the message has been sent to your mailbox, you can find a place to surf the Internet, or come to my dormitory, there will be classes in the afternoon!" ”

"What kind of picture?" Makihara asked.

"Very spooky photos! Creepy kind! Yin Hao said, but did not disclose the slightest content of the information.

"What time do you have class in the afternoon, if there is no conflict, come to my classroom." Mu Yuan said, "At two o'clock in the afternoon, the 7221 classroom of the Seven Teachings! ”

"Okay!" Yin Hao agreed.

Hanging up Yin Hao's phone, Mu Yuan found that there were several unread text messages in his phone.

Article 1: I've signed you up for the magic show, use snacks, don't mess me up, otherwise!

Article 2: How did you think about the things you promised me?

Article 3: I changed my number, this is my new number, remember it! Wait for me to come back and drink!

Article 4: Boy, you are dead, there are more ice cubes in the bedroom, maybe you can use it that day!

Mu Yuan looked at it blankly, I went, four text messages, all of them were unfamiliar numbers! Who is this! Mu Yuan read it again, and seemed to be a little frowned, the first one should be Xia Xue's, and the fourth should be Meng Yanmeng's Grand Police Officer, this kind of character who swears force at every turn is very right with her.

"What a level!" Mu Yuan pouted and said, "As a people's criminal policeman, with this culture, there are actually two typos in a text message!" ”

If Meng Yan knew that Mu Yuan had damaged her so much, she would probably go crazy again, and her lungs would explode, who would care about any typos.

So who sent the second and third articles? Especially the third one, Makihara is really worried about his IQ! I know who you are, and you drink another day, with this IQ, it's absolutely normal to forget to bring your wallet, and it's not necessarily who pays!

Putting away his thoughts, Mu Yuan thought of Yin Hao's phone call again, weird photos? The creepy kind?

What is it exactly? I'm really looking forward to it!

Suddenly, the text message rang out again.

"At eight o'clock tonight, please come to my house for dinner, address XXX, introduce someone to you, Liu Yihang!"