This time, the express delivery left two clues, one was the movement trajectory and the other was the express delivery.

A large number of police forces were investigating the investigation, and at the same time, a detailed investigation was also begun to be conducted on the express parcel, mainly targeting three key evidence.

First of all, the mineral water bottle was carefully inspected. Although only the fingerprints of the front desk, administrative manager, Liang Yongqing and others were found on it, I was very lucky to extract more than a dozen kinds of dandruff and biological tissue residues from the mineral water bottle, including a saliva residue.

This is a key clue, and these organizations were sent to monitor DNA and the results were soon released.

The DNA of these biological tissues and dander comes from five different people, and the most samples left behind is the DNA from a completely stranger, which is also the DNA that leaves saliva residues.

This person is likely the sender, and it is easy to imagine the situation at that time. Maybe when preparing this thing, the person picked up an empty mineral water bottle at hand and started making express parcels. Although he carefully erased his fingerprints, it was difficult for him to remove biological residues, so these were taken to the secret service department.

The second is the letter on A4 printing paper. This letter also reveals a lot of information. First of all, the inks. The chemical composition of the printing inks of each manufacturer is different. The printing inks in the font are analyzed molecularly, and then the inks that often appear on the market are compared. I quickly found that one batch of inks from an ink manufacturer is the same as the ink on the printing paper.

Taking this batch of ink as a clue, the ink was finally sent to three provinces and regions, and the agents who distribute this batch of ink were framed out.

Continue to track down the sales of ink, locking down every sales person who appears under the surveillance camera. Extract their videos and compare them with the portraits of the characters at hand now.

The source of paper can also be traced. Each paper mill has different execution processes for the types and content of chemicals used on the paper. Even under the same set of technology, there will be differences between different batches.

Through this difference, it is easy to lock the source of paper, and the ink sales area can be used to collect paper samples that have appeared in these areas, and soon the paper manufacturers and production batches are searched.

Then search for the sales area and dealers of this batch to find the degree of overlap with the ink dealer, use this degree of overlap to retrieve the corresponding monitoring, and find people to compare portraits.

The third key evidence is the express delivery form, which is the express delivery form filled out by the suspect himself. The font left on it can reveal a lot of information.

The font on the express delivery form was sent to the expert who specialized in taking notes and analyses, and soon a psychological portrait was enough:

......This is a young male, between the ages of 22 and 27, his life is relatively simple, and there is no overly complicated social relationship. This person has poor social experience. Maybe he is a student or a position that does not have frequent contact with others. This person is introverted and not good at socializing, similar to a technician. This person may have achieved some achievements, showing a certain degree of self-confidence and control in his brushstrokes, is satisfied with his current life, and is full of hope. He is in a high mood recently. Maybe he encounters some good things or is in a successful relationship. If it is the latter, maybe his girlfriend will be more beautiful, far beyond his psychological expectations...

A series of information is summarized. The Secret Service Department needs to combine all this information, and then compare all the selected people to find possible suspects.

At this time, the entire secret service department felt the huge workload and extremely low efficiency. At this time, Liu Huaiyi couldn't help but miss the big data system that Li Menghua was developing. If there were computer help, these tasks would be the matter of pressing a few buttons, right?

At this time, Liu Huaiyi also understood that, like a case like looking for a needle in a haystack, having a useful auxiliary detection software at hand is more important than anything else. A software is often as good as hundreds or even thousands of well-trained agents. The key is that it is not tired and always accurate. The data can be fully compared, which is much stronger than individual agents in information communication and comparison.

Now that the big data software has not been developed yet, the secret service department can only make things simple and keep investing in manpower, just rely on people to build up!

The surveillance videos related to ink dealers and paper dealers were searched repeatedly several times, but no useful clues were found, and only DNA, psychological portraits and character portraits were left.

The local survey of the address of the answer also showed results. After carefully visiting thousands of people, five people reported seeing the person in the portrait, or the person dressed in this outfit.

These five people were taken back to the secret service department for in-depth investigation. After various instrument tests, as well as hypnosis and awakening of memory, it was found that three of them had false alarms, which were entirely due to misleading by police officers' language.

This phenomenon is quite common. Some people have done statistics. When describing the appearance of the criminal and accusing the criminal, the error rate is often as high as more than 60%.

Because the brain memory of the human body has reprocessing attributes, the first visual image obtained by a person is first processed once after the picture enters the human brain.

How is this processing done?

First, a picture enters the brain, and the brain begins to recognize the picture, compare the differences in vision between the eyes, transform the plane image in the picture into a three-dimensional figure, forming a three-dimensional cognition of spatial position in the brain, and at the same time, the different color blocks and lines in the picture begin to be classified into this three-dimensional figure, which belong to one object, which belongs to another object, which is the ground, which is the house, and which is the human body. This requires the brain to process it step by step.

Camouflage clothing and spatial visual illusion use this characteristic of the brain to confuse the brain and form wrong cognition and classification.

There are also the kind of puzzles that specifically deceive the brain. Many people will see completely different patterns after seeing it. This is the brains of different people. They are different processing results in the process of visual abstraction, classification, and generalization.

Because the memory formation of the human brain is a process of visual signal reprocessing, it will be affected by many factors. After verbal hints, a person often changes his memory beyond recognition.

The three people who were falsely reported belonged to this type of person. They had not actually seen the suspect, but the police took the portrait in front of them. They looked at the painting carefully and unconsciously processed a false memory in their brains, believing that they had seen this person at some point.

The false positives were eliminated, and the valuable information provided by the two people I had actually met was very leisurely. They could only remember the approximate vague time period and just knew which direction the person went in which direction, so there was no other valuable information.

Next, an agent suggested that since there is a copy of printing paper, there are two types: one is that the paper was printed by the suspect at his home or his workplace, and the other is printed by him on the road. Since the express delivery mailing location has been locked, why not search for the surrounding typing and copying stores?

This is an idea. Print shops with a radius of five kilometers centered on the express delivery point were included in the search scope. Local police officers visited them one by one, but they still found nothing and found no trace of the suspect.

At this point, the case was in a deadlock again!

ps: Is it a great update today? Comrades, too, support me strongly!
Chapter completed!