After wiping the cup, wipe the glass. After wiping the glass, wipe the mirror. After wiping the smooth ones, wipe the coarse ones. After wiping the coarse ones, wipe the fine ones. After wiping the fine ones, wipe the soft ones. After wiping the soft ones, wipe the hard ones...
Exploration work, from a large perspective, is all kinds of things, but from a detailed perspective, it is all trivial and trivial.
The police all say that the investigation of cases is based on the accumulation of resources, which can be reflected during the on-site investigation.
Just like wiping DNA and fingerprints, laymen often think that as long as the suspect leaves DNA or fingerprints at the scene, he 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
For example, fingerprints are divided into 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 means are also based on the location and material of the fingerprint.
Different, adopt different solutions. Or powder, or pipeline, or smoke, or chemical reagents, or different chemical reagents, or different chemical reagents...
In view of this, in order to obtain a fingerprint, the on-site survey or trace inspection personnel first need to determine where the fingerprint may exist, and then observe it. The observation method can be with the naked eye using light or angle, or by breathing on a smooth surface. The same can be done
Observe with a magnifying glass or ultraviolet light. After determining the location of the fingerprint, the fingerprint can be extracted with powder, or chemically extracted with iodine fumigation or silver nitrate or other reagents.
Therefore, if a spider-man really climbed across the ceiling, the person doing the on-site investigation would most likely not find fingerprints on the ceiling.
DNA is even more troublesome than fingerprints.
After all, fingerprints can be seen, and sometimes DNA can be seen, but sometimes it can only be guessed.
It is common to extract DNA from the victim's toothbrush. Naturally, the police doing the extraction can't see anything. They can only guess that there is a high probability of DNA on the toothbrush.
If you switch to items with less high probability, such as shirts, bedsheets and other intimate clothing, or items such as drinking glasses and porcelain bowls, whether there is DNA on them is completely a matter of guessing.
The ability to do spot investigation is very obvious at this time. Some spot investigators think from the perspective of the criminal suspect, guess the opponent's movements, thereby finding possible clues, and then paint the powder in an orderly manner.
; Some of them just pack shirts, sheets and the like back, or just cut out a few pieces randomly, regardless of whether they are really useful...
However, in general, the more people involved in the investigation, the more capable they are, and the more time and energy they invest, the higher the probability of discovering clues and evidence.
Jiang Yuan's operating techniques seemed to Wang Zhong to be very strong, but during the murder case, he felt that it was more appropriate. If it were a theft case, it would be almost impossible to do what Jiang Yuan did.
Regarding the cost of DNA, the reagents alone cost 100 yuan less, and the number of times it can be done per unit time is even more limited. It is very likely that the line of biological test materials will not be able to queue up for a long time...
"Let's clean the bathroom again." Jiang Yuan took care of the bedroom, and the sky was getting dark.
Wang Zhong patted his head after hearing this, pointed to a large box of evidence bags, and said, "Why don't we come back tomorrow? There are hundreds of copies of these. Give them all to the laboratory, and they will go crazy."
Jiang Yuan explained: "There are more than half of them. It is estimated that no DNA can be extracted, so no reagents can be used. The murderer did it too cleanly. Look at the bedroom, the fingerprints in many places have been wiped clean. Again.
In addition, the victim shed so much blood, the murderer must have spent a lot of time in the bathroom, rinsing rags, or even taking a shower and washing clothes. The probability of DNA being mentioned in the bathroom is very high."
"Xiao Hu and the others also guessed the same, and they all checked it carefully." Wang Zhong said.
"The wipe was still too rough." Jiang Yuan had paid attention to the operations of Xiao Hu and others when dealing with the corpse, and there was nothing taboo about it at this time.
"Oh... Okay, I'll work overtime with you today." Wang Zhong didn't think so before, but now he began to realize that the skills of several spot investigators in the team were indeed a bit casual, as if they were doing their own fingerprints.
The technology is the same, and the best evaluation is probably "it works".
And just in the past few hours, the missing fingerprints that Jiang Yuan found may not necessarily solve the case, but they have proved that he and Lao Yan are not "usable" enough.
"Well..." The old man at the door couldn't stand still and said, "We have to go home for dinner."
"Just sign and go back." Wang Zhong actually didn't expect the old man to stay for long. The witnesses were all like this. They were either unwilling to get involved, wandering around and talking, or just impatient.
Wang Zhong had no idea of educating others, so he directly took the on-site inspection record, turned to the signature page, asked the two of them to write their names, then opened the door and let them out, only saying: "What you saw and heard today,
You can only tell the truth when asked by the court or relevant departments, and you cannot leak it out, otherwise you will be held criminally responsible."
The two old men went out and nodded impatiently and said, "I know, I know."
Wang Zhong nodded as usual, closed the door and went back to the house, continuing to help Jiang Yuan wipe his DNA and fingerprints.
The lighting in the bathroom is not good, making it more difficult to clean.
Jiang Yuan wiped it very vigorously.
Crime Scene Investigation LV4 not only improves his operational ability, but also his cognitive level.
Various crime theories actually explain the same truth: the longer the criminal stays at the crime scene, the more things he does, and the more flaws he exposes.
For example, the murderer this time seemed to have carefully cleaned up the crime scene and even took a bath calmly. But as far as Jiang Yuan understood, this just reflected the murderer's amateurism and arrogance.
Today's DNA technology can even identify identity information from sweat. It is absolutely impossible to clean the bathroom flawlessly in a short period of time. If you are a little more professional, you should at least cover the bathroom
Plastic, if the plastic is taken away directly and buried or burned, much less physical evidence information will be leaked.
However, in that case, there will be traces of tape or sticky on the scene...
Jiang Yuan was actually not sure where the murderer's DNA could be found. He was just young and had good physical strength, so he wiped it like crazy.
wipe.
Scratch...
Jiang Yuan is still in the excitement stage of a novice. He has just obtained the Crime Scene Investigation LV4 skill. The only scene he has ever really investigated is this one. Naturally, he tries and practices as much as he can.
Among the skills of current exploration, technique is of course very important, and meticulousness is indispensable. On the other hand, physical strength, concentration and other abilities are the key to reaching a higher level. This is like Xue Huaiyi falling out of favor with Wu Zetian,
Is it because he has gained more experience and improved his skills that he is disliked? Obviously not. In the same way, the Zhang brothers will not fall out of favor because they are young, reckless, and impulsive.
Wang Zhong lacked more than one or two of the above. However, although he was a little tired, he was led by Jiang Yuan and tried his best to support him.
Jiang Yuan especially carefully wiped the ceiling and corners of the bathroom.
The further he goes, the more careful and confident he becomes.
This house does not have dry and wet separation, but the bathroom area is small. When taking a shower, the probability of water splashing on the walls and ceiling is not low, and it is impossible to clean it thoroughly in a short time. The only problem is that it can
There is a question of whether DNA has been wiped off. The blood stains may have been washed away or destroyed, but if you want to wash away all traces of DNA, this person is probably still an amateur.
Ordinary people who commit unplanned murders will not normally learn relevant skills in advance. Even if they learn, they may not have to work hard and seriously, and they may not be proficient in learning, so there is a high probability that they will work hard and study hard and become proficient.
The police found him.
At night.
Jiang Yuan and Wang Zhong dragged their large and small bags back to the police station and went straight to the DNA laboratory.
Nowadays, there are more and more cases where DNA is used to directly solve crimes, and the police department’s investment in DNA laboratories is also increasing. Even Ningtai, a poor county, is under the guidance of various subsidies and policies, in accordance with the guidelines given by the ministries and commissions.
standards and built a DNA laboratory.
This is also the gold-eating beast unit of the police station. A total of three people work in the laboratory, which consumes more than 10% of the police station's funds every year, and the amount increases from time to time.
However, unlike what Wang Zhong expected, the DNA laboratory just silently accepted the piles of evidence bags and did not raise any objection.
They didn't even carefully check and criticize the biological test materials sent by Jiang Yuan and Wang Zhong.
"How come the old money man from DNA has become so easy to talk to?" Wang Zhong followed Jiang Yuan directly to the medical examiner's office and began to mutter.
In the forensic office, Wu Jun did not go home. Like most criminal police officers, he sat in the office and sorted out the information he had done during the day. Standing up and rubbing his eyes, Wu Jun said slowly: "In the afternoon, the team leader also issued
As for Temper, the problem now is that there are no clues, and the DNA laboratory is eager for you to send the test materials so as not to have nothing to do."
Jiang Yuan listened happily: "If you don't work at night, does it mean you have nothing to do?"
"The captain didn't even go home." Wu Jun said: "If nothing can be found, they will have to re-examine it themselves."
Wang Zhong looked at Jiang Yuan, tsked twice, and said: "It's in vain if they go. As far as their current investigation level is concerned, I don't mean to say that they can just forget about ordinary cases..."
Wu Jun interrupted Wang Zhong: "Do you think they don't know?"
"Uh..." Wang Zhong was speechless and returned to his office silently.
Jiang Yuan was quite satisfied, so he packed up and rolled out the camp bed in the office.
Until the noise started, the policemen who had been up all night started to quarrel.
"The DNA comparison has selected a person, Captain Liu took the person there." Wang Zhong was the first to rush into the office, with secretions still hanging from the corners of his eyes.
