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

Putting down the tea leaves, Lu Chuan continued to conduct technical identification and analysis of the garbage in the garbage bag.

Lu Chuan has already extracted the corresponding amount of some toilet paper and vegetable residues, and then sent them to the provincial technical identification center for trace evidence analysis.

The Dongzhou City Criminal Investigation Detachment does not have the ability to analyze trace species, so these technical identification work requires support from Shengcheng's Technical Identification Center.

The earliest we can get the result is tomorrow at noon.

From Lu Chuan's perspective, solving this case might not be particularly difficult.

Because the body fluids left by the suspect in the deceased's body have been extracted from the victim's DNA information.

The reason why this case is confirmed to be committed by the Red Killer is because the DNA information extracted from the victim's body is consistent with the DNA information extracted from the other 10 people.

Therefore, as long as the same DNA substance is found in the plastic bag, it can be determined whether the plastic bag was thrown by the murderer.

At the same time, if other clues can be used to determine who the owner of the plastic bag is, then the case may be solved.

Of course, this is only a theoretical statement. It is still uncertain whether the suspect can be identified in practice.

Because in the process of solving previous cases, the Dongzhou City Criminal Investigation Detachment also found some major clues.

With the help of crime-solving experts from the provincial department and experts dispatched by ministries and commissions to investigate the case, Lu Chuan found a number of directional clues in some files.

Unfortunately, 15 years have passed, and although there are many clues, the case has not been solved and the suspect has never been caught.

Another difference in this case is that the fingerprints and footprints left at the crime scene are not the same.

DNA information proved that the suspects in these cases were the same murderer, but the fingerprints and footprints extracted from the crime scenes did not point to the same person.

This is interesting.

Did this person have the assistance of other murderers when committing the crime, or did the other party simulate other people's fingerprints or footprints?
Soon Lu Chuan made some progress.

The method used to extract fingerprints from plastic bags is different from that of extracting other ordinary fingerprints.

The general powder method does not work, so Lu Chuan uses a powder method combined with fluorescent light irradiation.

It is easy to find fingerprints, but it is difficult to extract them and then conduct technical identification and analysis on them.

Lu Chuan usually uses a combination of multiple methods to extract fingerprints.

In this way, the generation of fingerprint breakpoints can be greatly reduced, and the probability of success in the fingerprint identification and analysis process may be greater.

The fingerprints taken on the plastic bag are mainly on the edge of the handle.

However, due to the irregular shape of the edges, the fingerprints taken were severely fragmented.

Previously, the on-site detectives from the Dongzhou City Criminal Investigation Detachment also planned to extract fingerprints from the plastic bag, but they were unsuccessful.

The main reason is that these fingerprints are too fragmented and have no shape at all. Even if they are extracted, they are just a scattered pile that cannot be pieced together, let alone identified and analyzed.

This time, fingerprint extraction was also a great challenge for Lu Chuan. He had never extracted fingerprints from such plastic bags when solving cases before. After fingerprint extraction, the most important step is to splice the fingerprints.

Even with Lu Chuan's top fingerprint identification technology and analysis skills, it was still quite difficult.

Lu Chuan wants to sort out these broken fingerprints one by one, and then virtualize the lines and breakpoints of these fingerprints.

This cannot be accomplished with the assistance of computers or other means; Lu Chuan has to compare them slowly by himself.

Not only are each person's fingerprints different, but this difference is reflected in multiple dimensions.

The first type is the specific shape of the fingerprint, which can be divided into three types: bucket shape, bow shape and dustpan shape.

It is very simple to classify fingerprints in this specific situation, and even ordinary people can tell them apart.

But for Lu Chuan, this kind of classification and analysis of specific shapes is completely unable to satisfy his fingerprint identification.

In general cases, most of the fingerprints left at the crime scene are obvious fingerprints, that is, fingerprints left on hard objects, such as tables and floors.

This type of fingerprint is generally visible to the naked eye and can be seen at many crime scenes, such as bloody fingerprints.

Another type of fingerprint that on-the-spot detectives often encounter is formed fingerprints.

This type of fingerprint is usually left on a soft carrier, such as on clay or candles. Fingerprints left on materials are all formed fingerprints.

Most of the fingerprints analyzed during the crime-solving process are actually the third type of fingerprints, called latent fingerprints.

Fingerprints are invisible to the naked eye and must be identified through some means or methods with the help of instruments such as ultraviolet lamps.

The main way latent fingerprints remain is through absorption by oil and sweat.

Theoretically, latent fingerprints can occur on the surface of any object.

Lu Chuan analyzed and sorted out these broken fingerprints, and the most important thing was to conduct virtual analysis of the texture direction of these fingerprints through the method of identifying feature points.

The fingerprints of different people have different bifurcation points, end points and intersection points.

However, the fingerprints of the same person will have different distribution trends. What Lu Chuan has to do now is to sort out these broken fingerprints one by one, and then find the fingerprints with similar width, similar texture and the same trend as these fingerprints, and then stitch them together to try to restore a complete fingerprint.

This is a technical job and a time-consuming job. Generally speaking, Lu Chuan analyzed that it would take several hours, or even a day, to analyze a fingerprint like this. Of course, it could take longer.

The fingerprints extracted from the garbage bag were too fragmented and their positions were irregular, so this time Lu Chuan might have to spend a day or even longer to piece the fingerprints together.

But for a top-level fingerprint like Lu Chuan, the criminal police first said that as long as the fingerprint exists, the other party will not be able to escape.

Even if there is no fingerprint of the target person in the system for comparison, as long as Lu Chuan has his eyes on this fingerprint, he can collect it from all the suspected criminal suspects and there is a chance of successful comparison.

While Lu Chuan was conducting a careful investigation and analysis of the black plastic bag, other groups were also advancing their work.

And there has been some progress. (End of this chapter)