Normal people's urine is usually colorless, transparent or slightly yellow. Although it contains a large amount of metabolic waste, it does not contain bacteria, so it can be drunk.
In addition, normal urine is weakly alkaline, so if people who are pursuing health must drink weakly alkaline water, urine can also be one of the choices.
At the same time, urine can provide a lot of information. Hospitals can use it to conduct urine tests, and criminal departments can also use it to obtain DNA.
Urine contains a small amount of exfoliated cells, and using them, DNA comparison can be done.
However, laymen know the ropes, and experts cannot pretend to be confused.
Although it is possible to extract DNA from urine, the difficulty is much higher than that from blood. First of all, the number of exfoliated cells contained in urine is relatively small, which requires more urine for easy extraction.
On the other hand, the urine at the scene was obviously poorly preserved. Good urine suitable for DNA extraction should be stored at low temperature.
Therefore, in the era when DNA technology was first promoted, that is, in the first decade of the 21st century, it was basically very difficult to extract DNA from urine, and there were very few similar cases. At that time, everyone compared DNA
It is still mainly blood and rice juice, and again it has to be oral epithelial cells such as toothbrushes and cigarette butts. Occasionally there is some hair, and it must have hair follicle tissue.
Nowadays, technology has improved, and the richness of DNA comparisons has become much higher. Not only does hair no longer require hair follicle tissue, but the requirements for extracting DNA from urine are also very low with the awesome DNA laboratory. By the way, a little trivia
If a man or woman suspects that the child is not his or hers, there is no need to take the child to an institution, and there is no need to draw blood to leave traces. Instead, he or she can take the child to urinate urine that can be collected, cover it with ice coke, and send it to the relevant testing agency.
, you can get the results soon. 47 is naturally more convenient for criminal suspects. Jiang Yuan used the wet cotton swab in front of him to collect as many urine spots as possible, and then merged several cotton swabs together.
Wrap it in filter paper and fold it into a beautiful triangle.
This method can maximize the integrity and original flavor of urine, which is the same as extracting blood spots.
Several trace inspectors from Chiyong City looked at Jiang Yuan's operations and were a little confused about his methods.
To be honest, there is nothing mysterious about Jiang Yuan's operation this time. It is the most basic and cautious approach, and few people can say whether it is good or bad.
However, the case seems to have made progress again, which is a very realistic result.
"Let the DNA laboratory rush." Jiang Yuan handed the urine sample to the trace examiner at the back and continued to search in the bathroom.
Liu Jinghui interrupted at this time and said, "There is a 90% chance that this person is closely related to the case and is probably a participant or insider in the case."
The detachment leader was only concerned about the case and immediately asked: "How to tell?"
Liu Jinghui said, "This is the den of the three-person gang. It should be said that it is the place where they plan to rob and dispose of the stolen goods. Except for the three people and the participants, it cannot be used to entertain guests."
The detachment leader nodded repeatedly after hearing this. He is not a policeman who is particularly good at solving crimes. In other words, he has certain criminal investigation abilities, but he focuses on management and has gradually become separated from front-line leadership. Let him make similar judgments by himself.
They didn't even believe themselves, but Liu Jinghui said it, and the detachment leader's mood immediately changed.
So, there should actually be four criminals? "The detachment leader used his brainpower to calculate 3 + 1.
Liu Jinghui glanced at Jiang Yuan and said with a smile: "The crime scene was at the victim's home. The perpetrators must be three people. As for the owner of the urine just found, I guess, guess, it must have been stolen." 1
The detachment leader was stunned, "Sale of stolen goods? Why?"
This answer was somewhat biased, and Liu Jinghui slowly explained: "First, this person does not seem to be an accomplice. The three suspects are all young men who are very young, and they are all young men who can fight hard.
What’s the use of having an accomplice like this when he has to urinate all the time? Just give him some money.”
"Second, there may be someone behind the scenes. But judging from the safe, he did not provide the corresponding items, such as an oxygen cutting machine. If there is a behind-the-scenes
If the latter is the boss, he should buy it or borrow it. But our investigation has made it very clear that the three of them went to the car scrapping factory to buy an oxygen cutting machine, which also shows that the three of them neither trust each other nor trust each other.
I don’t believe this guy.”
"Third, this man appeared at the foothold of the three-person gang. It must be because the three of them needed him, otherwise they would not have told him his location. Those three young men who had just committed a major crime and were about to run away needed him most.
What is it? It’s just money, documents, and a plan to escape.”
When Liu Jinghui said this, he raised his chin and said: "Although from our point of view, documents and escape plans are definitely more difficult. But in fact, the most valuable and hardest to obtain is still money. The cash at the victim's home
Very few. The main things that were lost were jewelry, gold, watches, and toys... The three of them had to exchange these things for money before they could escape. Therefore, what they need most at this time is someone who can sell the stolen goods."
"It makes sense, it makes sense..." The detachment leader nodded repeatedly. He now saw hope of solving the case. Listening to Liu Jinghui's words again, he felt very comfortable.
The conversation between the two ended, and the room fell into silence for a while.
Liu Jinghui and the detachment leader both frowned.
This atmosphere is wrong.
When investigating a crime scene, it is normal for someone to talk from time to time, or even chat. It's like if you picked up a condom, and I picked up a piece of hard toilet paper, everyone should hand it over.
Only by streaming a bit can you determine whether there was one session or two sessions in the room.
Just now, several trace inspectors followed Jiang Yuan, and they kept muttering in low voices, like the background sound in the forest. Now they suddenly stopped talking, as if everything in the forest suddenly became silent, obviously
Unreasonable.
Liu Jinghui and the detachment leader moved forward and saw a few birds at the door of the bathroom... no, several trace inspection comrades, stretching their necks to look at something.
Going further inside, I saw Jiang Yuan holding a tablet in his hand and making gestures.
"What...are you doing?" the detachment leader asked curiously.
"Separation of overlapping fingerprints..." The oldest tracer looked back at the detachment leader, with a trace of despair clearly in his eyes.
The detachment leader was stunned: "Did we find an overlapping fingerprint? How were they separated?"
"That's right." Trace Inspection repeated.
Liu Jinghui looked at Jiang Yuan and asked in a low voice: "What are we doing now?"
"I found several fingerprints on the toilet, and they all overlapped when I took them. I want to separate one out first and see if I can match the fourth person." Jiang Yuan said it very simply.
There are many fingerprints in this rental house, and it is also very messy. Considering that the three-person gang has only rented it for a short time, it is conceivable that most of the fingerprints in the house may come from the landlord, previous tenants, and previous tenants, etc.
people.
Although it is possible to collect all these fingerprints and compare them together before screening them, Jiang Yuan has many means and is not willing to wait that long.
After all, now that DNA has been collected and it is the most convincing evidence, the main purpose of collecting fingerprints is to make it faster.
A pursuit can last almost an hour, and the murderer must not be given a chance to breathe. Only by making the fugitive feel suffocated can the pursuit be successful.
In view of this, Jiang Yuan's choice was very simple. He took his fingerprint directly from the flush button of the toilet.
The fourth person peed in the toilet. Normally, he would press the flush button. Therefore, there is a high probability that there will be the fourth person's fingerprint on the flush button.
At the same time, there will also be fingerprints of three other people or even more people on the flush button.
The problem at this time is that the overlapping fingerprints cannot be distinguished at all, let alone matched by software - but this is only the understanding of ordinary fingerprint examiners.
At Jiang Yuan's level, if he wanted to, he could separate fingerprints through texture features.
This process is not easy, but Jiang Yuan can do it.
It's just that this scene is really heartbreaking for ordinary trace inspectors to watch - this kind of technique is very difficult to learn without some talent and God's blessing.
It's Jiang Yuan, also
It is a texture-by-texture analysis.
Current fingerprint technology can theoretically decompose overlapping fingerprints through software, but the error rate is too high, and the overlapping fingerprints obtained are basically unusable. If you meet a knowledgeable lawyer or something, you will easily be slapped in the face in court.
.
At this time, the most reliable method is manual work, which is extremely difficult.
Jiang Yuan made it easily with a tablet.
After marking two more sets of characteristic points, Jiang Yuan was soon in the top ten, winning one person.
"Leifhan. This guy has a history of selling stolen goods, and he also deals in fake certificates... he has a complete range of categories." Jiang Yuannian looked at the information in the competition and felt that this person seemed to be tailor-made.
But the detachment leader slapped his thigh hard: "Did the three-person gang buy the fake certificate from him?"
"It's very possible." Jiang Yuan nodded.
"This must be the case. Sell the stolen goods and provide documents!" The detachment leader couldn't wait.
If the identity documents of the trio were purchased from a fourth person, it would be easy to determine the current location of the trio by catching Revhan.
Once someone is arrested, the whole case will come to a perfect conclusion.
The more the detachment leader thought about it, the happier he became. He picked up his phone and made arrangements.
At this point, Jiang Yuan agreed with his judgment. He turned to Mu Zhiyang and said softly: "You can buy a high-speed rail ticket and go home."
