Chapter 79 Peaceful Breath

Afternoon.

The sun shines in the yard, and there is a peaceful atmosphere.

There are only six criminal police officers, working hard to send seven people and more to prison.

"Magnetic powder is fine."

"Let's use ultraviolet light first."

"This... ninhydrin."

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

Some people were not quite used to it at the beginning, but gradually, they began to get familiar with Jiang Yuan's style of doing things.

At this time, the crime scene is like a workshop or an office. The presence of technical experts will eventually lead everyone to the same or similar technical indicators, otherwise, the work cannot be done.

For fingerprints alone, the fingerprints scanned by the current surveyors in Ningtai County are for Yan Ge and Wang Zhong to do. The requirements of the latter two are probably clarity and accuracy. If they can't do it, they won't say much, just think that they are incompetent.

Jiang Yuan's requirements in this regard are very different, because he knows what he can do, so for the fingerprints used for comparison and for those fingerprints that need to be stored and processed, Jiang Yuan's requirements are naturally higher.

However, the most critical point is that Jiang Yuan can give a clear solution to obtain clear fingerprints.

Several on-site investigation police officers have never enjoyed such "teaching" after leaving school.

Just like ninhydrin to show fingerprints, this should be the most commonly used technology, including books and classrooms, and many crime scenes.

It is a chemical reaction, and its mechanism is relatively complex, but in terms of effect, the ninhydrin method can clearly show latent fingerprints on light-colored paper, tickets and even wooden products. This is a very useful and awesome solution.

But in real crime scenes, criminal police rarely use this solution.

It is no exaggeration to say that for most on-site investigations, the most commonly used, most used, and even the only solution is the powder method.

"One brush to go around the world" is the daily state of most criminal investigations.

Don't change the type of powder.

Today, the technicians of the Criminal Division Squadron were all doing the on-site investigation. In very rare cases, they would still use ninhydrin and 502 fumigation. But today, all the staff were mobilized, so there were so many technicians.

Usually, many small cases were scanned and stored by the criminal police and police officers of the police station on the spot, and many of them did not know how to use ninhydrin and 502 fumigation.

In fact, because they were rarely used, the technicians of the Criminal Division Squadron were not very skilled 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 arrive at the unit smoothly, then unless there is an unexpected situation today and the previous route is really impossible to take, otherwise, why change to another route?

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

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

Unless it is a non-smooth surface, textile, or fingerprint that cannot be revealed by powder, and it must be an important fingerprint, technicians will use ninhydrin.

This is equivalent to wind and rain. As long as the road is not washed away or blocked by emergencies, the road will basically not be changed.

However, in the past, it was Yan Ge and Wang Zhong who needed to analyze fingerprints, but now it is Jiang Yuan.

Jiang Yuan is like a unit that requires working hours and a unit that requires continuous reduction of commuting time. If the technicians on the scene want to meet this standard, it becomes very important to choose the right road.

Of course, it is important that everyone is willing to reduce commuting time, or in other words, willing to cooperate with Jiang Yuan to improve the quality of fingerprints stored in the database.

In criminal science and technology, this is a martial arts secret book, which is not only the capital for survival, but also a tool for self-improvement and self-improvement. Doing things is doing things, and most people are willing to do a better job.

And anything, wanting to do it well, is actually a bit difficult.

For example, ninhydrin. Anyone who has studied in the police academy for three or four years can say "I know this well".

But when asked, "Which formula of ninhydrin do you usually use?", most people will be speechless.

Only technicians like Wang Zhong, who have really used ninhydrin, can easily come up with a formula of 1g ninhydrin and 100g anhydrous ethanol, and say, "We used to use more acetone, but now the management is stricter, and it is not good to take out too much acetone..."

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

"Huh, a formula that requires ether? Add... 60g?" Wang Zhong was thinking about the formula, and it really seemed that he was not very clear.

Jiang Yuan said: "We need 2g of ninhydrin, then add 5g of anhydrous ethanol, and then 5g of ether. Because the latent fingerprint we are going to make now is on a colloid object, after adding ether, it will be much clearer. The 1:100 ethanol formula you used just now is OK for paper, but it won't work well for colloid objects."

"You said that I have learned the formula before." Wang Zhong patted his forehead. He learned it, but he only used it for so many years and couldn't remember the formula at all.

As Wang Zhong said this, he prepared ninhydrin on the spot and brushed it on a kraft paper bag.

Jiang Yuan moved his lips, but didn't make any further requests.

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

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

The inherent understanding of criminal police is to find fingerprints on smooth objects. In other words, in terms of everyone's technical level, it is not easy to figure out fingerprints on smooth objects.

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

He sprinkled the powder on the LV old flower leather bag where the fingerprints were to be extracted, then raised the glue gun, sprayed out a thick glue-like liquid, and heated it with a hair dryer.

Several investigators nearby were stunned.

"We still have this equipment?" The investigators were full of question marks.

"Found it in the warehouse." Jiang Yuan held up the glue gun and started to move around, saying, "I guess they bought it in sets."

"That's for sure, now they are all packed in packages..." Xiankan looked helpless and suddenly felt that he knew nothing about the situation in the bureau.