civil forensic

Chapter 79 Peaceful Breath
afternoon.

The sun shines in the yard, creating a peaceful atmosphere.

There are only six criminal policemen, and they are busy with great difficulty in order to send seven people and more people to prison.

"Magnetic powder is fine."

"Let's use ultraviolet light first."

"This... ninhydrin."

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

Some of them didn't quite get used to it at the beginning, but gradually, they became 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 strong technical personnel will eventually lead everyone to the same or similar technical indicators, otherwise, the work will not be able to continue.

In terms of fingerprints alone, the fingerprints scanned by the surveyors in Ningtai County were done for Yan Ge and Wang Zhong.The requirements of the latter two are about clarity and accuracy. If you can't do it, you won't say much, just think that your ability is not good enough.

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

However, the most important thing is that Jiang Yuan can give a clear plan, so as to get a clear fingerprint.

After leaving the school, several survey policemen really never enjoyed such "teaching".

It's like ninhydrin to reveal fingerprints, which should be the most commonly used technique, including books and classrooms, as well as many crime scenes.

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

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

It is no exaggeration to say that for the vast majority of on-site surveys, the most commonly used, most used, and even the only method that will be used is the powder method.

"Going around the world with a brush" is the daily state of most criminal investigations.

Not changing the type of powder.

All the technicians doing the survey today are technicians from the criminal squadron. In very rare cases, they still use ninhydrin and 502 to fumigate them.But today is a state where all the staff are dispatched, so there are so many technicians coming out.

In normal times, many small cases are put into storage by the criminal police and the police from the police station on the spot, and many of them don't know how to use ninhydrin and 502 fumigant at all.

In fact, the technicians of the criminal squadron are not very proficient in using ninhydrin and 502 fumigants because they are rarely used.

This is also easy to understand. If a person takes the same route to work every day and can reach the unit smoothly, then unless something unexpected happens today, the previous route is really impossible to go. Otherwise, why change it? What about other routes?

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

Everyone didn't even bother to change the type of powder.

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

This is equivalent to wind and rain, as long as the road is not washed away or blocked due to emergencies, it is basically the rhythm of not changing the road.

However, Yan Ge and Wang Zhong were the ones who needed to analyze fingerprints before, but now it is Jiang Yuan.

Jiang Yuan is like a unit that requires working hours, a unit that requires continuous reduction of commuting time.For on-site technicians, if they want to meet this standard, it becomes very important to choose the right path.

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

In criminal science and technology, this is the secret book of martial arts. It is not only the capital to live and work, but also a tool to improve oneself and self-improvement. Doing things is doing things, and most people are still willing to do a little bit better.

And anything, if you want to do it well, it 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" loudly.

But when you really ask: "Which ninhydrin formula do you usually use", [-]% of them have to misfire.

Only a technician like Wang Zhong who has really used ninhydrin can easily come up with the formula of 1g ninhydrin and 100g absolute ethanol, and said: "We used to use acetone more, but now the management is stricter. Acetone is not easy to take out too much..."

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

"Eh, the formula to add ether? Add... 60g?" Wang Zhong was thinking about the formula now, but he really didn't seem very clear.

Jiang Yuandao: "2g of ninhydrin is needed, then 33.5g of absolute ethanol, and then 66.5g of ether. Because the latent fingerprint to be done now is on the colloidal object, after adding ether, it will be clearly displayed It’s much clearer. The [-]:[-] ethanol formula you just used is fine on paper, but it won’t work well on gelatinous objects.”

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

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

Jiang Yuan moved his lips and made no further requests.

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

No one asked any more questions, so Jiang Yuan found an object that was not smooth and started to do it himself.

The inherent understanding of criminal police is to look for fingerprints on smooth objects.In other words, as far as everyone's technical level is concerned, it is not easy to figure out the fingerprints on smooth objects.

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

I saw him sprinkle the powder on the LV presbyopic leather bag to extract fingerprints, then raised the glue gun, sprayed out a thick gelatinous liquid, and heated it with a hair dryer.

The few surveyors next to him were stunned.

"Do we still have this equipment?" The head of the current survey was full of question marks.

"I found it in the warehouse." Holding the glue gun, Jiang Yuan began to run around, and said: "I guess when I bought it, I bought it as a set."

"That's for sure, it's all packaged now..." Xian Kan felt helpless looking at it, and suddenly felt that he knew nothing about the situation in the game.

(End of this chapter)