Luoyang Reservoir is located in a reservoir in Luojia Village, Jinghai City, which is located in a remote area, and Li Xiang does not know that there is such a reservoir in that place.

Li Xiang flipped through the case file and slowly learned about this old adult case.

In 2009, there was an uncle surnamed Liu who came to wild fishing, hooked down, found that his hand sank, thinking that he was on a big fish, and caught it to take a look.

Uncle Liu suddenly became thirty years younger.

This was a female corpse, so frightened that he hurriedly called the police, and soon, the Jinghai City Criminal Investigation Team rushed to the scene to investigate.

The victim was well dressed but had several hollow bricks tied to his body, which was clearly a case of body dumping, and the suspect did not want the body to surface.

But I didn't expect to be caught.

So the police investigated the crime scene, and the reservoir was not the first crime scene, but the place where the body was dumped, but the traces of the scene had already been seriously damaged, and no valuable clues were obtained.

The victim's face was unrecognizable because she had been immersed in water for many days, and the police did not find anything on her body that could prove the identity of the victim, such as an ID card.

The medical examiner also conducted an autopsy on the victim, the victim was female, 165cm tall, aged 23-25 years old, the cause of death was mechanical asphyxiation, the time of death was seven days ago, there were no signs of struggle on her body, there was sex before death, but the forensic doctor did not extract the tadpole from her body.

The hollow bricks tied to the victim's body are common hollow bricks when locals build houses, and the reservoir at the time of the crime was located in a remote and barren area, and outsiders had no one to guide them, and they rarely came here, so the police judged that the murderer was likely to be a local of Luojia Village, and an adult male with good physical strength, otherwise he would not be able to complete this series of actions.

So the police took the reservoir as the center to investigate all the villages within a radius of 3 kilometers, whether anyone used hollow bricks to build houses at home, and finally found a brick wall in Luojia Village that was the same as the hollow bricks tied to the victim's body, and the murderer was very likely to take the hollow bricks from here.

But this place is accessible in all directions, and anyone, as long as they have the heart, can easily remove a few hollow bricks, which can only confirm that the murderer has been here, and there are no other clues.

It is imperative for the police to identify the victim first.

In the murder case, the source of the body is determined, so it is not far from solving the case.

At that time, it was the Qingming Festival, and the police thought that the woman had come to sweep the grave, so they visited and investigated people in Luojia Village and several surrounding villages.

Unfortunately, no villagers knew the victims, and there were no missing persons in the village during this time, so the case reached a dead end.

Subsequently, the police took pictures of the victim's clothes and posted them online to collect clues, but there were no valuable clues.

If the source of the corpse cannot be determined, the suspect cannot be locked, the suspect cannot be caught, and the case cannot be solved.

The case was shelved in this way, and it became a problem for the Jinghai City Criminal Investigation Team.

With the development of criminal investigation technology, the victim's DNA has long been entered into the public security system, and the criminal investigation team will review the case every year and compare the victim's DNA, but there have been no clues.

has been delayed again and again, and this case has been going on for more than ten years, and the source of the body has still not been found.

Through the understanding of the case file, the police have not done nothing over the years, they invited portrait experts from the province to restore the victim's face, trying to restore the victim's face portrait through this method.

The police came to Luojia Village again with the portrait and asked the villagers to identify them, but no one knew the victim.

At present, the only clue is the DNA of the victim.

After reading the case file, Li Xiang's mobile phone also released the system task again:

[Mission Name: Luoyang Reservoir Sinking Case]

[Mission description: A 14-year-old unsolved unsolved case, touched the heart of the Jinghai City Criminal Investigation Team, the old case is investigated year after year, but the clues are minimal, under the principle that the murder case must be solved, the Jinghai police will concentrate their efforts to re-raise the case again, you as a newcomer to the Criminal Investigation Squadron, you are bound to take over this baton, and investigate the case to the end. 】

[Task requirements: Assist the Jinghai police to find out the truth of the case]

[Reward: XP +600, Diamond +3000]

"How? Li Xiang, what do you think of this case? Mao Ji asked after seeing that Li Xiang had finished turning over the case.

Because in the last case, Li Xiang put forward constructive suggestions, allowing them to discover the truth that the murderers wanted to hide in advance, which pointed out the direction for their investigation work and saved a lot of police resources.

Therefore, Mao Ji is still full of expectations for Li Xiang, and he hopes that Li Xiang can also play a certain role in this case, and it is best to find some new clues or ideas through the case file.

"There are too few clues, the source of the corpse can't be determined, and our DNA database has never been able to match the victim's family?"

"Comparing DNA data is not a simple task, each human cell has 23 pairs (46) pairs of chromosomes, which come from the father and mother. The 23 chromosomes provided by each husband and wife are paired with each other after fertilization to form 23 pairs (46) of the child's chromosomes, and so on and so on constitutes a continuation of life. ”

"Since there are about 3 billion nucleotides in the human body that make up the entire chromosomal system, this makes it very difficult to align, and the error is also very large. In order to reduce this error, we usually use the DNA data of both parents to compare together, so that as long as the victim's parents report the crime at the police station, then the police will collect their DNA data, so that the identity of the victim can be more accurately detected. ”

Mao Ji knew that Li Xiang was not from a professional background, and for some basic DNA data comparison, it was also some hearsay fragmented knowledge, thinking that as long as he knew the victim's DNA data, he could quickly find the victim's family through big data, even if it was a relative of the same clan, he could also hide under the comparison of DNA data.

To some extent, there is nothing wrong with this statement, but it really only stays in theory and does not start from reality.

There are many kinds of DNA alignment techniques, and different DNA detection methods have different accuracy, sensitivity, and specificity, and it is necessary to choose an appropriate alignment method to ensure the accuracy of alignment.

Matching identical DNA is very fast, but when comparing parents and children, the error is very large.

In order to ensure the accuracy of the comparison, the police used the comparison of parents.

Hearing Mao Ji's explanation, Li Xiang understood the basic situation about DNA comparison, but at the same time, he also raised his own doubts: "What if the victim is a single-parent family?" ”

"Uh~"

Mao Ji was stunned, they have always used the parent-to-parent comparison method, and the accuracy of this comparison is the highest, but they subconsciously ignore the factor of single parent.

"You're right, the victim may also be a single-parent family, but if you compare single-parent families, the error will be relatively large."

"Try it, anyway, a dead horse is a live horse doctor."

Li Xiang didn't understand this, and he didn't know how big the data error of the single-parent comparison would be, but this didn't prevent him from talking about it, anyway, there were no other clues at present.

"Well, that's a direction, we can really try it, do you have any other opinions?"

Sometimes, they have been in this system, and the idea of solving the case is somewhat solidified, and the predecessors have confirmed their identities through the two-parent comparison method, and they have been using it to this day, and they have not considered the single-parent comparison with a relatively large error.

Now that Li wants to mention it, it breaks the frame of thinking and is refreshing, so I want to hear if he has any other opinions.

"There is another question, the reservoir is in a remote area, and the police also suspect that the murderer is a local, since the source of the body cannot be found, can it be investigated from the murderer?"

"The police also checked back then, but there were no clues."

Li Xiang nodded, it is true that even the source of the corpse cannot be determined, how to find the murderer?

The murderer will not see the police coming, so he will take the initiative to confess to the police, without the support of evidence, no criminal suspect will take the initiative to confess his crimes to the police.

Except, of course, those who surrender themselves.

If the murderer wanted to turn himself in, he would not choose to throw the body.

Another day passed, Cao Gang convened everyone and met again for a meeting on the Luoyang Reservoir sinking case.

"Li Xiang, have you finished reading the case?"

"Well, Team Cao, I've finished reading it." Li Xiang nodded.

"The focus of our next work is to return to this case, more than ten years, every year, but I hope you don't get discouraged, don't think that it's been more than ten years, anyway, you can't solve it, and you have to show a 200% attitude to have the possibility of solving the case."

Because this is an old case, and there are very few clues at the scene of the crime, the difficulty of solving the case has increased exponentially, Cao Gang is also worried that the case is too complicated, so that everyone will lose confidence in this case, so before every meeting, he has to cheer everyone up and cheer them up.

"Let's first re-examine all the details of the whole case."

Cao Gang took everyone to sort out all the circumstances of this case again, and also put forward his own views:

"The motive for the murder in this case has always been doubtful, and there are also two motive speculations, one is robbery and murder, no property and mobile phones and other items were found on the victim's body, it is possible that the murderer killed and dumped the body after the robbery, but the opponents of this speculation believe that the Luoyang Reservoir is very remote, there are no locals to bring it, and it is impossible for a little girl from outside to come to this place, even if she comes to travel, it is impossible to completely avoid the sight of the locals."

Because the police had already visited the entire village, even the neighboring villages, based on the victim's clothes and sketches, the villagers said that they had never seen the girl, which is also strong evidence against the robbery and murder faction.

The opposition believes that this may be a love killing, and the murderer is likely to be a local, he knows the terrain of Luoyang Reservoir, so he threw the body after completing the killing, but the clue returned to the original point again, no villager has seen this girl, so who did she come to Luoyang to find? How did they meet? ”

Cao Gang also wanted to break his head for this case, every time a question was born, he would stubbornly grasp this line, and then track it down until the line was completely broken, and then recomb it, find new suspicious points, and then track it down, constantly repeating and rebuilding.

It can be seen how much effort he has put into this case.

"Everyone basically understands this case, and they all talk about it, brainstorming, and maybe the clues will be summed up in the process of discussion."

When Li Xiang listened to Cao Gang's views on this case and his speculation about the motive for the killing, there was always a flash of inspiration, and every time he wanted to catch it, he couldn't catch it, which made him very distressed.

At this time, Mao Ji glanced at Li Xiang and saw that he didn't say the single parent theory they discussed together yesterday, so he had to say for him: "Team Cao, when Li Xiang and I discussed the case yesterday, he had a point of view that I think is a good direction, you can try it." ”

"Oh? In what direction? ”

"At present, we use the method of parental confirmation and comparison to improve the accuracy of the victim's identity through DNA data comparison, but if the victim is a single-parent family, then there are certain limitations to using this method, so he proposed to use the single-parent comparison method to try, and I also think I can try it."

"Single parents? This is a direction, but the success rate of the comparison is really not guaranteed, but this is also a way that is not a solution, I can let the technical department try it. ”

Cao Gang listened to Mao Ji's words, and looked at the contemplative Li Xiang in surprise, he was able to put forward this point of view, which shows that he is very flexible in his thinking about solving cases.

For old cases, you are not afraid of large errors, you are not afraid of high difficulty, you are afraid that there are no clues, and you have no place to use your strength.

Although the accuracy of single-parent comparison is not high and the error is relatively large, the data samples with high similarity can be screened out through massive comparison, and then verified one by one, and the workload of this is increased geometrically.

They don't want to use this method to investigate unless they have to.

"If we can locate the location of the victim's household registration, then the success rate will be relatively high in the national system comparison." Cao Gang thought about it, although the success rate of single-parent comparison is not high, it is not impossible to improve the success rate, and a large part of the error can be screened out through the division of regions.

"It's a paradox, we can only know where the victim is registered if we know her identity, but if we know her identity, we don't need to compare DNA data to confirm the identity of the victim." When Su Jiayi heard Cao Gang's words, she felt that this sentence was equivalent to not saying it, knowing the location of the victim's household registration, and the identity of the victim had long been clear.

"There is a way, it is man-made, everyone thinks about it."

Just now when he heard the motive for the murder analyzed by Team Cao, when he heard the location of the victim's household registration, Li Xiang finally caught that trace of inspiration, so he said: "Actually, it is not difficult to know where the victim was when he was alive. ”

Perhaps, in the current situation, it is somewhat difficult to know the victim's household registration, but it is still possible to know where she was during her lifetime.

"Huh? What can you do? ”

When everyone heard that Li wanted to have a way, they immediately cast concerned eyes.

This is a case that has been hanging for 14 years, what can you do?

(End of chapter)