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

Chapter 1144 Discovering clues
When it comes to on-site investigations, Lu Chuan still believes in his own judgment. The details of each on-site investigation by the criminal police are different.

Lu Chuan had already seen in the file that the criminal police from Tianzhou City Public Security Bureau also collected fingerprints from the door, and the comparison showed nothing unusual.

But just because others didn’t notice it doesn’t mean Lu Chuan didn’t notice it. Otherwise, how could there be differences in business skills?
However, Lu Chuan also knew that it had been a week since the crime occurred, and Wang Hong still lived in the room every day, so many traces might not have been left at the crime scene.

The fingerprints collected from the door handle may not be the fingerprints taken at that time. Even if there were fingerprints at that time, they may be covered because the internet celebrity opens and closes the door every day.

But it doesn't matter. Collecting fingerprints is better than not collecting them, and it can also be compared with the fingerprints collected by the Tianshan District Criminal Police Brigade on the same day.

According to some details described in the file, the room was cleaned at that time.

The on-site investigators from the Tianshan District Criminal Police Brigade did not collect any fingerprints or footprints of strangers during the first investigation.

From this point of view, the scene should have been cleaned.

However, there were obvious signs of rummaging at the scene, but not all cabinets were opened.

Otherwise, if someone committed a crime, or a robbery or murder, they would not have left behind Wang Lili's bank card with more than 4 yuan in it.

This time, Lu Chuan started his inspection from the entrance door and scanned inside inch by inch, not missing a single detail.

All the debris in the gaps between the floor tiles and in the door cracks were picked out and placed in collection bags.

This time, Lu Chuan conducted the on-site investigation according to the standards of criminal cases.

Every step, including on-site survey and photography, on-site excavation, ultraviolet light irradiation, etc., was done extremely meticulously.

Following behind him was the on-site investigation detective from the Tianshan District Criminal Police Brigade. He was the one who conducted the first on-site investigation. This time, seeing that Lu Chuan, deputy director of the High-tech Zone Branch, was personally doing it, he quickly took out a small notebook to record some relevant details.

They had heard of Lu Chuan's name a long time ago, but unfortunately they had never had the chance to study with him. This opportunity was rare and could not be missed.

Other criminal police officers, including Wang Dongtian, were also carefully observing Lu Chuan's movements.

Wang Dongtian himself is a former criminal policeman. As a criminal policeman, he sometimes does not necessarily bring on-site investigation police with him when he goes to the scene, so criminal police generally also have some on-site investigation techniques.

Moreover, the so-called fingerprint detectives and on-site investigation detectives have gradually emerged in recent years as the criminal investigation technology has developed and the conditions for competing for personnel have improved.

In the past, it was basically field police who did these tasks part-time.

The reason why some of the better detectives are so good at solving cases is because they are very meticulous and can discover details at the crime scene that other detectives cannot.

Wang Dongtian was a leader here back then. He could always find things at the crime scene that others didn't notice.

It is precisely these inconspicuous things, things that others easily overlook, that Wang Dongtian can often find key information from these clues.

It is also because of this that Wang Dongtian has been able to step by step reach his current position and become the deputy director of the Tianshan District Public Security Bureau.

Now watching Lu Chuan doing the on-site investigation was simply a kind of enjoyment, and Wang Dongtian also followed behind to watch and learn. Although there were signs of cleaning at the scene, Lu Chuan still believed that as long as the murderer had been at the crime scene, there would definitely be some material exchange information left behind.

When he was in police academy, Lu Chuan took a course called crime scene reconstruction.

The so-called crime scene reconstruction is to infer the location information of the victim and the murderer at the time of the crime based on some details of the crime scene.

No single most important law is Locard's law of exchange.

Theoretically speaking, as long as a person has been to a space, no matter how long he stays in this space, he will eventually leave some traces of his in this space.

For example, smell footprints, fingerprints, etc.

Even if the other party has cleaned these traces, it is impossible to completely eliminate them. For example, fingerprints contain human sweat and oil.

Theoretically, although fingerprints can be removed, the residual substances cannot be eliminated 100%. It’s just that current scientific and technological means are unable to extract 100% of these substances.

For example, the human body is in the process of metabolism all the time, and necrotic cells fall off the body every moment.

These substances are invisible to the naked eye, and may not even be discovered by a microscope. The substances will definitely remain at the scene, but it depends on whether you can discover them, or whether you have the ability to discover them.

Facts have proved that Lu Chuan's on-site investigation ability is indeed stronger than that of most people.

Starting from the entrance door, he went inside step by step, inch by inch. Lu Chuan did not miss any details, including under the sofa, under the table legs, etc. Qin Chuan did not miss any details.

The entire on-site investigation lasted a very long time. Everyone watched Lu Chuan conduct the investigation in silence, and quickly an hour passed.

What Lu Chuan is holding in his hand now is a piece of information provided by Wang Hong, which is the kitchen knife found on the refrigerator.

This kitchen knife is a bone-cutting knife that is not often used in Wang Hong’s family.

According to the internet celebrity, this kitchen knife is usually kept in the kitchen cabinet and is not often taken out for use, so he did not notice it at the time. Moreover, the kitchen knife was found on the top of the refrigerator. If he had not wiped the dust off the refrigerator that day, he probably would not have found it.

Through careful observation, Lu Chuan found that there were separate gaps on the kitchen knife, some of which were relatively fresh, but some were relatively old.

"This round, curled edge is probably left by chopping bones."

Although there was no blood on the kitchen knife, just by looking at the gaps, Lu Chuan knew roughly how these gaps were formed.

According to the internet celebrity, this kitchen knife has not been used for a long time. The old gaps should be left by chopping bones in the past, but what about the fresh gaps?

"Director Wang, I'll take this knife back to the Criminal Investigation Division. The equipment in the Investigation Office is more complete, and some special trace evidence can be identified through the equipment there."

When Lu Chuan was working in the Criminal Investigation Detachment, the on-site investigation equipment there underwent a lot of updates. Basically, the Criminal Investigation Detachment has the most popular and cutting-edge equipment on the market, and its laboratories are one of the best in the province.

(End of this chapter)