Attending ex-girlfriend's wedding, arresting the groom's officer on the spot

The case of the Criminal Investigation Detachment of TZ City can be said to have been quite a failure.

The real murderer was never found, and the wronged innocent people committed suicide in the detention center.

Now Lu Chuan can even imagine how terrified he must be when he saw the photo sent by the restaurant owner as a criminal policeman of the TZ City Criminal Investigation Detachment.

There are also five blood words left by the deceased on the wall of the detention center.

I am wronged!
Even if Lu Chuan was not there, he could imagine how helpless and sad these words should be.

"What do they want us to do?"

Liu Guodong sighed deeply.

The criminal investigation detachment of TZ City has handled the case to such an extent, and now it has sent it to itself for help. It must have discovered something, but I can't figure it out.

"Blood fingerprints."

Qin Yong took out the bloody fingerprints found on the murder weapon in the file.

"The most important evidence for the TZ City Criminal Investigation Detachment to lock down the suspect is this blood 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 paid attention to by the survey.

What's more, this fingerprint was found on the murder weapon.

In fact, fingerprints cannot be extracted at most crime scenes.

In terms of probability, only about 20.00% of criminal cases can be detected through fingerprints, or even lower.

For example, the fingerprint battle organized by the Ministry of Finance did not involve a particularly large number of criminal cases.

Also, there are valid and ineffective claims about fingerprinting.

In some scenes, fingerprints can be collected, but there are no murderers.

And in some scenes, even if the murderer left fingerprints, they might not be able to collect them.

Lu Chuan's fingerprint collection skills are specifically for fingerprint collection.

"Because of the existence of this fingerprint, the police handling the case at that time directly locked 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 restaurant where the innocent were eating, although there were no surveillance cameras, the boss was not impressed with the dead at the time.

But there are cameras around the restaurant.

Yesterday, the criminal investigation detachment of TZ City captured the video of the innocent suicide victim passing through the surveillance at the entrance of a photography building more than 200 meters away from the restaurant.

Further corroborating the photo evidence brought by the restaurant owner.

"When things were cleared up, they did a more detailed analysis of the fingerprints and found this."

Qin Yong pulled out another piece of printing paper.

"There appears to be a layer of fingerprints on top of the fingerprints."

The lines on the printing paper are still blood fingerprints, almost exactly the same as the previous picture.

But with Lu Chuan's ability, in fact, when he just saw this picture, he knew that they were really wrong.

"Someone used a fingerprint sleeve to simulate the fingerprints of innocent people."

Qin Yong was not surprised that Lu Chuan discovered this.

"Yes, Taizhou Criminal Investigation Detachment sent the fingerprints to the Technical Appraisal Center of the Provincial Department yesterday afternoon, but they were not successfully extracted there either."

"The suggestion from the provincial department is for you to help take a look."

"Are you sure?"

Lu Chuan frowned.

This superimposed type of fingerprint is not uncommon.

Superimposed fingerprints will appear in most crime scenes.

In fact, there are certain methods and skills to do this kind of fingerprint separation.

The fingerprint identification experts of the provincial department, such as Tian Rong and Lu Chuan, were also familiar with them when they participated in the fingerprint battle last time.

It stands to reason that superimposing fingerprints in the hands of an expert of Tian Rong's level would not have too much difficulty in identification and analysis.

There is only one reason why the Ministry of Finance did not get this fingerprint.

Superimposed fingerprints are too light.

When the murderer committed the crime, he should have been wearing something like a fingerprint mold glove.

The fingerprints left on the murder weapon belonged to the innocent suicide victim, while the fingerprints of the real murderer were printed on the mold by pressure.

Due to the uneven texture of fingerprints, the mold pressure is unbalanced.

So there is a layer of fingerprints that are as delicate as a spider's 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 haven't done this type of fingerprint analysis before, so I'll take it back and try."

"Okay, it's successful, and there's nothing to do if it doesn't. After all, the experts from the provincial department didn't make a successful appraisal."

Qin Yong was actually under no pressure.

Since the Criminal Investigation Detachment of TZ City came here, there was no reason not to help.

However, no one can guarantee whether it will be successful or not.

Surveying the office now.

Lu Chuan was staring at the computer in a daze.

General superimposed fingerprints can be processed by image layering.

But the premise is that the superimposed fingerprints are relatively clear, or the depth of the traces is similar.

But now this fingerprint is obviously not good.

The fingerprint of the real murderer, because the indentation left by the fingerprint mold glove is very inconspicuous.

Paint software can't even recognize the existence of superimposed fingerprints at all.

Lu Chuan has just tried the general map number transformation and the method of using data to strengthen it.

Compared with the spider-like covered fingerprints, the data flow of blood fingerprints is too huge, and it is difficult to strip data, let alone enhance things.

"How about it, it's not easy to handle?"

Lao Bai handed Lu Chuan a cigarette.

In the past, when Lu Chuan was doing fingerprint identification, it was basically a one-screen data stream, and the results could be produced 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 it was different. Lu Chuan had been staring at the fingerprints on the computer screen for half an hour in a daze, but he hadn't started any action.

After taking the cigarette, Lu Chuan nodded.

"The superimposed fingerprint is too shallow, and there is no way to extract it with general methods. I have to study it."

"Take your time, but if you can't handle it, no one in our province can handle it."

After Lu Chuan participated in the fingerprint competition organized by the provincial department last time, he has already faintly been called No. 1 in fingerprint identification and analysis in the whole province.

Recently, many criminal investigation detachments from other cities have come to help.

Mathematical transformations didn't work, and the image layers that came with the software couldn't be recognized. After studying for a long time, Lu Chuan decided that he could only program by himself.

In fact, the most important thing in the separation and extraction of superimposed fingerprints is to layer the image.

The method Lu Chuancai adopted was more complicated.

The underlying blood fingerprints are dark in color and heavy in lines, while the covering fingerprints on top are light in color and thin in lines.

Since this is the case, the gray value of each fingerprint ridge line is very different.

The gray value of the blood fingerprint and the coverage fingerprint are in two ranges.

Theoretically speaking, as long as Lu Chuan can distinguish the gray value of the image, and then extract the images of different gray value areas, he can separate the two superimposed fingerprints. (end of this chapter)