Afternoon.

The sun was shining in the yard, creating an atmosphere of peace.

Only six criminal investigators were working hard to send seven or more people to prison.

"Magnetic powder will do."

"Let's use ultraviolet light first."

"How about ninhydrin?"

Jiang Yuan had been at the crime scene for a few hours and easily gained control of the situation.

At first, some of the investigators were not used to his methods, but they gradually became familiar with his style.

The crime scene was like a workshop or office, where the presence of a skilled technician would lead everyone towards a common or similar technical standard. Otherwise, the work would not be possible.

For example, the fingerprints found by the investigators in Ningtai County were sent to Yan Ge and Wang Zhong. Their requirements were simply that the fingerprints be clear and accurate. If they couldn't do it, they wouldn't say much and just admit their own limitations.

Jiang Yuan's requirements were much higher because he knew what he was capable of. For fingerprints used for comparison and those that needed to be stored, Jiang Yuan's demands were naturally higher.

However, the most critical point was that Jiang Yuan could provide a clear plan to obtain clear fingerprints.

Several investigators had never received such guidance since leaving school.

For example, ninhydrin was the most commonly used technique, including in textbooks, classrooms, and many crime scenes.

It was a chemical reaction with a complex mechanism, but in terms of effectiveness, the ninhydrin method was able to clearly reveal latent fingerprints on light-colored paper, documents, and even wooden objects. It was a very useful and powerful technique.

However, in reality, criminal investigators rarely used this method.

To put it bluntly, the most commonly used and even the only method used in most crime scene investigations was the powder method.

"Brushing the world with one brush" was the daily routine of most criminal investigations.

They didn't even change the type of powder.

Today, the technicians doing the on-site investigation were from the Criminal Science Department. In very rare cases, they would use ninhydrin and 502 fuming, but only when everyone was present.

In normal cases, many small cases were handled by the criminal investigators and police officers on the spot, and many of them didn't even know how to use ninhydrin and 502 fuming.

In fact, because they were rarely used, the technicians from the Criminal Science Department were not very skilled in using ninhydrin and 502 fuming.

This was also easy to understand. If a person takes the same route to work every day and can always reach their destination smoothly, why would they change their route unless there was an unexpected situation that made it impossible to take the usual route?

The technicians in Ningtai County were like this. If fingerprints could be found with powder, they would definitely use powder. They were even too lazy to change the type of powder.Unless it's a non-smooth surface, textiles, or fingerprints that can't be revealed by powder and are important, technicians will use ninhydrin.

This is like driving on the same road unless it's washed away or blocked due to unforeseen circumstances.

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

Jiang Yuan is like a company that requires punctuality and constantly reducing commuting time. For on-site technicians, choosing the right route is very important if they want to meet this standard.

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

In forensic science and technology, this is like a secret martial art technique. It's not only the capital to survive but also a tool for self-improvement and self-improvement. Most people still want to do a little better.

And anything that wants to be done well is actually a bit difficult.

For example, ninhydrin. Anyone who has studied in a police school for three or four years can confidently say, "I'm familiar with this."

But when asked, "Which ninhydrin formula do you usually use?" Eight out of ten people will be stumped.

Only technicians like Wang Zhong, who have actually 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's not easy to get too much acetone out..."

Jiang Yuan gives a merciless response, "I suggest adding ether."

"Huh, we need to add ether to the formula? Add... 60g?" Wang Zhong is now trying to remember the formula, but it seems that he's not very clear.

Jiang Yuan says, "You need 2g of ninhydrin, then add 33.5g of anhydrous ethanol, and then 66.5g of ether. Because the latent fingerprints we're dealing with now are on a gelatinous object, adding ether will make it much clearer. The one-to-one hundred ethanol formula you just used may work on paper, but it won't be effective on gelatinous objects."

"You're saying that I've learned this formula before." Wang Zhong hits his forehead. He has indeed learned it before, but after only using it for a few years, he can't remember it.

Wang Zhong then prepares the ninhydrin on-site and brushes it onto a leather bag.

Jiang Yuan doesn't make any further demands.

The ninhydrin takes one to two hours to develop, but there are other ways to speed up the process. However, there is still plenty of time, so Jiang Yuan doesn't need to be too picky.

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No one else asks any questions, so Jiang Yuan starts working on non-smooth objects himself.

The inherent understanding of the detectives is to find fingerprints on smooth objects. Or to put it another way, given everyone's technical level, it's not easy to identify fingerprints on smooth objects.

Jiang Yuan then takes out a glue gun from the on-site investigation box.

He sprinkles powder on the LV reading glasses case where the fingerprints need to be extracted, then picks up the glue gun and sprays thick glue onto it, and heats it up with a hairdryer.

The other on-site technicians are stunned.

"We have this equipment?" The on-site technicians are full of question marks."It was found in the warehouse." Jiang Yuan held up the glue gun and began to move around, saying, "I guess they bought it as a set."

"That's for sure, now they are all packaged together..." The on-site investigator looked helpless and suddenly felt like they knew nothing about the situation.