Chapter 79

Afternoon.

Sunlight sprinkled in the courtyard, a peaceful atmosphere.

Only six criminal police officers were working hard and excellently to send seven people and more people to prison.

"Magnetic powder is okay."

"Better use ultraviolet light first."

"This... ninhydrin, let's use."

Jiang Yuan stayed at the crime scene for several hours and easily gained the right to speak at the crime scene.

A few people were a bit unaccustomed at the beginning, but gradually, they began to become familiar with Jiang Yuan's style of doing things.

The crime scene at this time is like a workshop or an office. The existence of technical experts will eventually lead everyone to a same or similar technical indicator; otherwise, work cannot be carried out.

Just in terms of fingerprints, the fingerprints scanned by the Ningtai County crime scene investigators were for Yan Ge and Wang Zhong to do. The requirements of the latter two were about clarity and accuracy. If they couldn't do it, they wouldn't say much, just thinking that their ability was insufficient.

Jiang Yuan's requirements in this regard were extremely different, because he knew to what extent he could do it, so for the fingerprints used for comparison, for these fingerprints that need to be processed into the database, Jiang Yuan's requirements were naturally higher.

However, the most critical point is that Jiang Yuan can provide a clear plan, thereby obtaining clear fingerprints.

Several crime scene investigation police officers, after leaving school, really hadn't enjoyed such "teaching."

It's like ninhydrin revealing fingerprints; this should have been the most commonly used technology, including books and classrooms, and many crime scenes.

It is a chemical reaction, and the mechanism itself is relatively complex, but in terms of effect, the ninhydrin method can clearly reveal latent fingerprints on light-colored paper, tickets, and even wooden products. This is a very easy-to-use and awesome plan.

But at the actual crime scene, criminal police rarely use this plan.

It is no exaggeration to say that the vast majority of crime scene investigations use the powder method most commonly, most frequently, and even the only plan they will use.

"A brush walks the world" is the daily state of most criminal investigations.

And they don't change the type of powder.

The people doing the crime scene investigation today are all technicians from the Criminal Investigation Squadron. On very rare occasions, they will still use ninhydrin and 502 fumigation. But today is a state where everyone is dispatched, so there will be so many technicians out.

Usually, many small cases are scanned for fingerprints on the spot by the criminal police and police station police officers who go to the scene, and many of them don't know how to use ninhydrin and 502 fumigation at all.

In fact, because they use it less, the technicians of the Criminal Investigation Squadron are not very proficient in using ninhydrin and 502 fumigation.

This is also easy to understand. If a person takes the same route to work every day and can successfully reach the unit, then unless an accident occurs today and the previous route really cannot be taken, why change to other routes?

The technicians in Ningtai County are like this. As long as the fingerprints can be scanned out with powder, they will definitely be scanned with powder.

Everyone is even too lazy to change the type of powder.

Unless it is a non-smooth surface, textiles, fingerprints that really cannot be revealed with powder, and they must be important fingerprints, only then will technicians use ninhydrin.

This is equivalent to wind and rain; as long as the road is not washed away, and not blocked by sudden events, it is basically a rhythm of not changing the road.

However, in the past, when facing fingerprints, the people who needed to parse fingerprints were Yan Ge and Wang Zhong, but now it is Jiang Yuan.

Jiang Yuan is like a unit that requires working hours, a unit that requires continuously reducing commuting time. If the technicians at the scene want to meet this standard, choosing the right road becomes very important.

Of course, the important thing is that everyone is also willing to reduce commuting time, or rather, willing to cooperate with Jiang Yuan to improve the quality of fingerprints in the database.

In criminal science and technology, this is a martial arts secret book. It is both the capital to settle down and a tool to improve oneself and improve oneself. Doing things is doing things, and most people are still willing to do it better.

And anything, if you want to do it well, is actually a bit difficult.

For example, ninhydrin; anyone who has studied in police school for three or four years can loudly say "I am familiar with this."

But when really asked, "Which ninhydrin formula do you usually use," 80% of people will have to be dumbfounded.

Only technicians like Wang Zhong, who have really used ninhydrin, can easily take out the formula of 1g ninhydrin and 100g anhydrous ethanol, and say, "We used more acetone in the past, but now the management is relatively strict, and it is not easy to take out too much acetone..."

Jiang Yuan gave a ruthless response: "It is recommended to add ether."

"Eh, a formula that requires ether? Add... 60g?" Wang Zhong thought of the formula on the spot, and it really didn't seem very clear.

Jiang Yuan said, "Need 2g of ninhydrin, then add 33.5g of anhydrous ethanol, and then 66.5g of ether. Because the latent fingerprint to be done now is on a colloidal object, after adding ether, it will be significantly clearer. The one-to-one hundred ethanol formula you just used is okay on paper, but on colloidal objects, the effect will not be good."

"You say my brain, the formula I learned before." Wang Zhong patted his forehead. He had learned it, but he had only used it for a few years, and it was basically a plan he couldn't remember.

Wang Zhong said, and then prepared ninhydrin on the spot, and then brushed it onto a kraft paper bag.

Jiang Yuan moved his lips and did not make further requirements.

The color development time of ninhydrin is one to two hours, but there are other ways to speed it up, but now time is still abundant, and Jiang Yuan doesn't need to be nitpicky.

No one asked any more questions, so Jiang Yuan found a non-smooth object and did it himself.

The inherent understanding of criminal police is to find fingerprints on smooth objects. Or rather, in terms of everyone's technical level, it is not easy to clarify fingerprints on smooth objects.

Jiang Yuan took out a glue gun from the crime scene investigation box.

I saw him sprinkle powder on the LV old flower leather bag from which fingerprints were to be extracted, then raise the glue gun, spray out thick glue-like liquid, and heat it with a hair dryer.

Several crime scene investigators next to him were stunned.

"Do we still have this equipment?" The person doing the crime scene investigation was full of question marks.

"Found in the warehouse." Jiang Yuan raised the glue gun and began to run rampant everywhere, saying, "It is estimated that when it was bought, it was bought as a set."

"That's for sure, now they are all packed in bags..." The crime scene investigator looked very helpless, suddenly feeling that he knew nothing about the situation in the bureau.