civil forensic

The urine of normal people is usually colorless, transparent or slightly yellow. Although it contains a lot of metabolic waste, it does not contain bacteria, so it can be drunk.

In addition, normal urine is weakly alkaline, so if people who pursue health must drink weakly alkaline water, urine can also be one of the choices.

At the same time, there is a lot of information that can be provided in urine.Hospitals can be used to do urine tests, and criminal departments can also be used to produce DNA.

Urine contains a small amount of exfoliated cells, which can be used for DNA comparison.

However, laymen look at the doorway, and experts can't pretend to be confused.

Although DNA can be extracted 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 to facilitate extraction.

On the other hand, the urine on site was obviously not well preserved, and 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 21 years of the 10st century, it was basically very difficult to extract DNA through urine, and there were very few similar cases.At that time, the DNA comparisons were still mainly based on blood and beetroot, and again, oral epithelial cells such as toothbrushes and cigarette butts, and occasionally some hair, and hair follicle tissue.

Nowadays, with the improvement of technology, the richness of DNA comparison is much higher.Not only the hair follicle tissue is no longer needed, but the awesome DNA laboratory also has very low requirements for extracting DNA from urine.By the way, a piece of cold knowledge, if a certain man or woman suspects that the child is not his own, there is no need to take the child to an institution, and there is no need to draw blood to leave traces, just take the child to urinate that can be collected, and use ice cola to calm down. Send it to the relevant testing agency, and you will get the result soon. 47 Naturally, it is more convenient for criminal suspects.Jiang Yuan collected as many urine spots as possible with a wet cotton swab, then combined several cotton swabs, wrapped them with filter paper, and folded them into a beautiful triangle.

This method can maximize the integrity and original taste of the urine, which is the same as extracting blood spots.

Several trace inspectors from Chiyong City watched Jiang Yuan's operation, and were a little confused about his way.

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't tell whether it is good or bad.

However, the case seems to have progressed again, which is a very realistic result.

"Let the DNA laboratory expedite." Jiang Yuan handed the urine sample to the trace examiner behind, and continued to search in the bathroom.

Liu Jinghui interjected at this time, saying, "There is a [-]% chance that this person has a strong connection with the case, and most of them are participants or insiders of the case."

The detachment leader only cared about the case, and immediately asked, "How do you say it?"

Liu Jinghui said, "This is the den of the three-person gang. It should be said that it is the place where they are going to rob and dispose of the stolen goods. Except for the three and the participants, it is impossible to use it to entertain guests."

The detachment leader nodded repeatedly.He is not a policeman who is particularly good at solving crimes. In other words, he has certain criminal investigation skills, but he is more focused on management, and he has gradually separated from the front-line leaders.Let him make a similar judgment by himself, the detachment leader himself didn't believe himself, but Liu Jinghui said, the detachment leader's mood changed immediately.

So, there should be 4 actual criminals? "The detachment leader exhausted his brainpower and calculated 3+1.

Liu Jinghui glanced at Jiang Yuan, and said with a smile: "The crime scene, that is, the victim's home, the perpetrators must be three people. As for the owner of the urine just found, I guess, well, guess, it should be sold." 1
The detachment leader was taken aback, "Sold stolen goods? Why?"

This answer is a little off, but Liu Jinghui slowly explained: "First, this person doesn't look like an accomplice. The three suspects are all young men who can fight and fight hard. This man runs around every time he urinates, what's the use of having such a partner? Just give him money."

"Secondly, it might be the mastermind behind the scenes. But judging from the matter of the safe, he did not provide corresponding items, such as oxygen cutters. If there is a mastermind
In the words of the postmaster, he should be the one to 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 the oxygen cutting machine together, which also shows that the three of them neither trust each other nor this one. "

"Third. This person appeared at the foothold of the trio's gang. It must be because the trio needed him, otherwise they would not have told his location. Those three young men who just committed a major crime and were about to run away need it the most. What is it? It’s nothing more than 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 Rarely, what was lost was mainly jewellery, gold, watches, and Wenwan... The three of them had to exchange these things into money before they could escape, so what they needed most at this time was a guy who sold stolen goods."

"It makes sense, it makes sense..." The detachment leader nodded again and again, he now saw the hope of solving the case, and listening to Liu Jinghui's words, he felt very pleasing to the ear.

The conversation between the two ended, and the room fell into silence for a while.

Both Liu Jinghui and the detachment leader frowned.

The atmosphere is wrong.

During crime scene investigation, it is normal for people to talk from time to time, or even to chat. It’s like you picked up a condom, and I picked up a piece of stiff toilet paper, please hand it over.

Only after a while can we determine whether there was one cannonball in the room or two.

Just now, several trace inspectors followed Jiang Yuan, muttering in a low voice, like the background sound in the forest.At this moment, he suddenly stopped talking, as if everything in the forest suddenly became silent, which was obviously unreasonable.

Liu Jinghui and the detachment leader moved closer together, and saw a few birds at the door of the bathroom... No, some comrades from the inspection department were stretching their necks to look at something.

Going further in, I saw Jiang Yuan holding a tablet in his hand and gesturing.

"What is this...?" the detachment leader asked curiously.

"Separation of overlapping fingerprints..." Hen Jian, the oldest man, looked back at the detachment leader, with a hint of despair evident in his eyes.

The detachment leader was taken aback: "Did you find an overlapping fingerprint? How did you separate it?"

"Yes." Henjian repeated.

Liu Jinghui looked at Jiang Yuan and asked softly, "What are we doing now?"

"I found a few fingerprints on the toilet, and they all overlapped when I took them. I want to separate one first to see if I can match the fourth person." Jiang Yuan said very simply.

There are many fingerprints in this rental house, and they are also very messy.Given that the gang of three only rented for a short period of time, it is conceivable that most of the fingerprints in the house may come from the landlord, the previous tenant, and the previous boss.

Although it is possible to collect all these fingerprints and compare them centrally before screening, but Jiang Yuan has the means, so he is unwilling to wait so long.

After all, now that DNA has been collected, and it is the most convincing evidence, then the main purpose of collecting fingerprints is to be quick.

Chasing and fleeing this kind of thing, almost an hour is an hour, and the murderer must not be given a chance to breathe.Only when the fugitive feels suffocated can the pursuit succeed.

In view of this, Jiang Yuan's choice was very simple. He directly took his fingerprints from the flush button of the toilet.

The fourth person peed in the toilet. Normally, he should press the flush button. Therefore, there is a high probability that the fourth person's fingerprint will be on the flush button.

At the same time, there will be fingerprints of other three people or even more people on the flush key.

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 trace inspectors.

At Jiang Yuan's level, as long as he wanted to, he could separate fingerprints through texture features.

This process is not easy, but Jiang Yuan can do it.

It's just this scene, which is really heartbreaking for ordinary tracers to watch-this kind of technology is difficult to learn without a bit of talent and without God's rewards.

Even Jiang Yuan,
It is the analysis of a texture and a texture.

The current fingerprint technology can theoretically decompose overlapping fingerprints through software, but the error rate is too high, and the resolved overlapping fingerprints are basically unusable.When you meet a knowledgeable lawyer or something, it is easy to slap your face in court on the spot.

At this time, the most reliable thing is artificial, and the difficulty is extremely high.

Jiang Yuan used a tablet to make it easily.

Then mark two groups of feature points, and soon, Jiang Yuan was among the dozen or so, and one of them was selected.

"Leifhan. This person has a history of selling stolen goods, and he also sells false certificates...there is a complete range." Jiang Yuan read the information in the comparison, and felt that this person was tailor-made.

The detachment leader slapped his thigh vigorously: "Did you buy the false certificate of the gang of three from him?"

"Very likely." Jiang Yuan nodded.

"It must be like this. Sell the stolen goods and provide documents!" The detachment leader couldn't wait.

If the identity documents of the trio were purchased from the fourth person, then by capturing Leifhan, it is easy to determine the current location of the trio.

Once the person is arrested at that time, the whole case will be a happy ending.

The detachment leader became happier the more he thought about it, picked up his phone, and made arrangements.

At this point, Jiang Yuan and his judgment were also consistent, and he turned his head and whispered to Mu Zhiyang: "You can buy a high-speed rail ticket and go home."