Chapter: 43

Wang Zhong took the key from the office, lifted the security belt casually, opened the door and entered, and then locked the door to change clothes. He asked the two retired old men who were under the age to stand in a corner, not allowed to speak, not move, and not allowed to take pictures.

"Where do we start?" Wang Zhong didn't plan to come, and he didn't have the confidence to come for a re-examination, but Jiang Yuan had an idea, so he still came along.

Jiang Yuan looked around and said slowly: "Let's start from the beginning."

Following his voice came the translucent interface that the system slowly unfolded:

Mission: start from scratch

Task content: Conduct repeated investigations on the scene of Xue Ming's case to obtain clues and evidence.

Jiang Yuan stared at the system interface for a few seconds before it disappeared.

"Start from the beginning?" Wang Zhong listened a little silly, then leaned closer to Jiang Yuan, and asked in a low voice: "Is it necessary?"

"Try it." Jiang Yuan said, spread out the equipment, then picked up a glass from the shoe cabinet at the door, soaked some water with a cotton swab, and wiped it gently.

Although the time period of acquaintance, my qualifications are a little deeper. But deep down, Wang Zhong is convinced of Jiang Yuan. For skills such as fingerprints, the gap in strength is too easy to show.

After standing still for a moment, Jiang Yuan's actions made Wang Zhong speechless.

Ordinary surveyors wipe the cup, or in other words, when the surveyors in Ningtai County wipe the cup, they directly use a cotton swab to wipe around the mouth of the cup. Although this method can also wipe out possible DNA, it has never It's all just a shorthand. Or rather, a common practice of incompetence.

Jiang Yuan's rubbing method, but Wang Zhong has only seen it on rare occasions. I saw that Jiang Yuan first dipped the cotton swab in water, and then squeezed it until it was half dry. When wiping, he will not wipe a large area, but choose a position on the mouth of the cup, rub the cotton swab up and down, and wipe it three to four times evenly, trying to wipe the DNA that may exist on it.

After wiping one point, Jiang Yuan wiped again at a certain point after a period of time. After several times, the DNA extraction of a cup was completed.

Doing so will naturally take more time than swiping around in a circle, but the probability of extracting DNA is also much higher.

Although Wang Zhong had never tried Jiang Yuan's method of swabbing DNA before, but based on the details Jiang Yuan showed, Wang Zhong knew that Jiang Yuan's rank was really higher than the team's current survey.

For example, a cotton swab that is semi-dry but not wet transfers DNA more easily than a cotton swab that is dry rubbed, and it is also easier to transfer DNA than a cotton swab that is saturated with water. The so-called don't mix with mud, don't get wet.

Using the way northerners understand it as an example, a cotton swab is like a bath towel. If you rub your dry skin with a dry bath towel, you won’t get much off the skin, and a bath towel soaked in water will only slip back and forth. If you can't remove much dirt by rubbing, you have to use a half-dry towel to rub the skin that is half-dry and not wet. The effect is the best, and the most things can be rubbed away.

To use the way non-northern people understand it as an example, a cotton swab is like a tongue. If you wipe your tongue dry to lick the dry skin, you won't be able to lick much. The effect of moistening the tongue with water is not good. The half-dry tongue must lick the half-dry skin for the best effect and the best state of friction.

Similarly, Jiang Yuan's method of wiping at one point is more effective than the method of wiping around a circle. Still using the way northerners understand it as an example, this is like rubbing at fixed points with a scrub towel, and using a scrub towel to pull a big saw, and the rubbed things cannot be counted. Using the way of understanding of non-northern people as an example, licking a spot is more effective than licking all over the place.

Jiang Yuan really has something, so Wang Zhong stopped talking, and simply followed Jiang Yuan to help him.

After working in the trace inspection position of the Criminal Division Squadron for several years, Wang Zhong has long understood that there are some things that you understand when you see them, or even easy to understand, but it doesn’t mean that you can think of them, and it doesn’t mean that you can think of them. If you use it correctly, it doesn't mean that you use it well, and if you use it well, it doesn't mean that you use it quickly.

Using a way that anyone who has participated in nine-year compulsory education can understand as an example, there are a total of five formulas in Eulerian geometry, and a total of one hundred and ten formulas in Newton’s three laws. Normal people can understand it after listening to the class, but they may not be able to understand it when they see the questions. No matter which formula you use, you may not use it right if you think about it. If you use it right, you may not use it well, and if you use it well, you may not use it quickly.

Wang Zhong also appeared on the scene all the year round to do surveys. Seeing that Jiang Yuan could do it meticulously, quickly, and quickly, he was too surprised. Fortunately, when he was doing fingerprints, he was used to helping Jiang Yuan. Once he was acquainted with him, he gradually became smoother. He even felt quite comfortable doing it.

After wiping the cup, wipe the glass, after wiping the glass, wipe the mirror, after wiping the light, rub the rough one, after the thick one, wipe the thin one, after wiping the thin one, wipe the soft one, after wipe the soft one, wipe the hard one...

Survey work, from a large perspective, is of all kinds, but from a detailed perspective, it is all small and trivial matters.

The police say that the detection of the case is based on the accumulation of resources, which can be reflected during the investigation period.

Just like wiping DNA and fingerprints, laymen often think that as long as criminal suspects leave DNA or fingerprints at the scene, they will be found by on-site investigators, but in fact, there are no advanced instruments in the world that can accurately detect All fingerprints and DNA within a certain range

Like fingerprints, first of all, there are three types: dominant, plastic and recessive. The former two can be seen, while the latter, as the name suggests, requires certain means to see. And these methods also adopt different schemes according to the different materials of the location where the fingerprint is located. Or powder, or pipe, or smoke, or chemical, or different chemical, or different chemical...

In view of this, in order to obtain a fingerprint, the surveyor or trace inspection personnel first need to judge where there may be fingerprints, and then observe. The observation method can be carried out by naked eyes with the help of light or angle, or by breathing on a smooth surface. Observe with a magnifying glass or ultraviolet light. After the location of the fingerprint is determined, the fingerprint is extracted by brushing powder, or using iodine smoke or silver nitrate or other reagents for chemical extraction.