This case handled by the TZ City Criminal Investigation Detachment can be said to be quite a failure.
The real murderer was not found, and innocent people who were wrongly accused committed suicide in the detention center.
Lu Chuan could even imagine now how frightened the criminal police officer of the TZ City Criminal Investigation Detachment would be when he saw the photo sent by the restaurant owner.
There are also five bloody words left by the deceased on the wall of the detention center.
I was wronged!
Even if Lu Chuan was not present at the scene, he could still imagine how helpless and sorrowful these words must be.
"What do they want us to do?"
Liu Guodong sighed deeply.
The TZ City Criminal Investigation Detachment has handled the case to this extent, and now it's been sent to me for help. They must have discovered something, but they can't handle it themselves.
"Blood fingerprints."
Qin Yong pulled out the bloody fingerprint found on the murder weapon in the file.
"The most important evidence used by the TZ City Criminal Investigation Detachment to identify the criminal suspect is this bloody fingerprint."
Lu Chuan nodded. In general criminal cases, fingerprints are the most important criminal evidence.
Any fingerprints that appear at the crime scene are the most important evidence that must be taken seriously during the current investigation.
What's more, the fingerprint was found on the murder weapon.
In fact, fingerprints cannot be extracted from most crime scenes.
In terms of probability, only about 20% of criminal cases can be solved through fingerprint pointing, or even lower.
For example, the number of criminal cases involved in the fingerprint battle organized by the provincial department is not particularly large.
In addition, fingerprint extraction also has valid and invalid opinions.
Fingerprints can be collected at some scenes, but there is no murderer.
In some scenes, even if the murderer leaves fingerprints, it may not be possible to collect them.
Lu Chuan's fingerprint collection skills are specifically designed for fingerprint collection.
"Because of the existence of this fingerprint, the police handling the case directly targeted the so-called suspect who committed suicide in the detention center."
"Ignored some of the alibi proposed by the other party."
This point is introduced in the dossier.
The innocent man was eating in the restaurant. Although there were no surveillance cameras, the boss was not very impressed with the deceased at the time.
But there are cameras around the restaurant.
Yesterday, the TZ City Criminal Investigation Detachment obtained a video of the innocent suicide passing by during the time of the crime from the surveillance camera at the entrance of a photography building more than 200 meters away from the restaurant.
This was further supported by the photographic evidence brought over by the restaurant owner.
"After they figured it out, they conducted a more detailed analysis of the fingerprints and found this."
Qin Yong pulled out another piece of printing paper.
"There seems to be a layer of fingerprints on top of the fingerprints."
The pattern on the printing paper was still bloody fingerprints, almost exactly the same as the previous picture.
But with Lu Chuan's ability, he knew when he saw this picture that they really made a mistake.
"Someone used a fingerprint cover to simulate the fingerprints of an innocent person."
Qin Yong was not surprised that Lu Chuan could discover this.
"Yes, the Taizhou Criminal Investigation Detachment sent the fingerprints to the Provincial Technical Identification Center yesterday afternoon, but the extraction was not successful."
"The suggestion from the provincial department is for you to help me take a look."
"Are you sure?"
Lu Chuan frowned.
This type of superimposed fingerprint is not uncommon.
Superimposed fingerprints will appear at most crime scenes.
There are actually certain methods and techniques for doing this kind of fingerprint separation.
Fingerprint identification experts from the provincial department, such as Tian Rong and Lu Chuan, were also familiar with them when they participated in the last fingerprint battle.
It stands to reason that superimposed fingerprints would not be too difficult to identify and analyze in the hands of an expert of Tian Rong's level.
The reason why the provincial department has not solved this fingerprint is that
A reason.
The superimposed fingerprints are too light.
The murderer should have been wearing something like a fingerprint mold glove when he committed the crime.
The fingerprints left on the murder weapon were those of the innocent suicide, but the fingerprints of the real murderer were imprinted on the mold through pressure.
Due to the uneven texture of fingerprints, the mold pressure is unbalanced.
Therefore, there is a layer of fingerprints as delicate as a spider web, covering the blood fingerprints.
What Lu Chuan has to do now is to separate the spider web-like fingerprints from the blood fingerprints.
Then compare within the system.
"I've never done this type of fingerprint identification analysis before. I'll take it back and try it."
"Okay, it works. If it doesn't work, there's nothing we can do about it. After all, the experts from the provincial department have not succeeded in appraising it."
Qin Yong actually has no pressure.
Since the TZ City Criminal Investigation Detachment has come to find him, there is no reason not to help.
However, no one can guarantee whether it will work or not.
The current survey office.
Lu Chuan was staring at the computer in a daze.
General superimposed fingerprints can be processed using image layering.
But the premise is that the superimposed fingerprints are relatively clear, or the depth of the marks is similar.
But now this fingerprint is obviously not good.
The fingerprints of the real murderer were very inconspicuous because of the fingerprint mold gloves.
Painting software cannot even recognize the presence of superimposed fingerprints.
Lu Chuan had just tried the general image-to-digital transformation method of using data to enhance it.
Compared with spider-like covered fingerprints, the data flow of blood fingerprints is too large, and it is difficult to strip the data, let alone enhance it.
"How's it going? It's not easy to do?"
Lao Bai handed Lu Chuan a cigarette.
When Lu Chuan did fingerprint identification in the past, it was basically a one-screen data stream, and the results could be obtained in ten minutes, half an hour, or at most one or two hours.
Although Lao Bai couldn't understand the whole process, he could clearly feel a sense of ease.
This time was different. Lu Chuan had been staring at the fingerprints on the computer screen in a daze for half an hour, but he never made any move.
Taking the cigarette, Lu Chuan nodded.
"The superimposed fingerprints are too shallow and cannot be extracted using normal methods. I have to study it."
"Take your time, but if you can't handle it, probably no one in our province can handle it."
After Lu Chuan participated in the last fingerprint competition organized by the provincial department, he was already vaguely known as the first person in fingerprint identification and analysis in the province.
Recently, many other city criminal investigation detachments have come to help.
The mathematical transformation didn't work, and the image layering that came with the software couldn't be recognized. After studying for a long time, Lu Chuan decided that he could only rely on programming by himself.
In fact, the most important thing for separation and extraction of superimposed fingerprints is to layer the image.
The method Lu Chuancai adopted was more complicated.
The underlying blood fingerprint is dark in color and has heavy lines, while the overlying fingerprint is light in color and has thin lines.
In this case, the gray value of each fingerprint ridge is very different.
The grayscale values of blood fingerprints and covered fingerprints are in two ranges.
Theoretically, Lu Chuan can separate two superimposed fingerprints as long as he can distinguish the gray value of the image and then extract the images in different gray value areas.
