I made a copy at the police station

Chapter 103: The case of corpses buried in Luoyang Reservoir (please subscribe, please vote!)

Luoyang Reservoir is located in a reservoir in Luojia Village, Jinghai City. It is located in a remote place, and Li Xiang did not know that there was such a reservoir in that place.

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

In 2009, an old man surnamed Liu came to go fishing. As soon as he hooked the hook, he found that his hand sank. He thought he had caught a big fish, so he fished it up to take a look.

Uncle Liu suddenly became 30 years younger.

This was a female corpse, which frightened him and quickly called the police. Soon, the Jinghai City Criminal Investigation Team rushed to the scene to conduct an investigation.

The victim was fully clothed, but several hollow bricks were tied to his body. This was obviously a body dumping case, and the suspect did not want the body to surface.

But I didn't expect to be caught.

So the police conducted an investigation around the crime scene. The reservoir was not the first crime scene, but the place where the body was dumped. However, the traces at the scene had been severely damaged and no valuable clues were obtained.

Because the victim had been soaked in water for many days, she had already decomposed severely and her face could not be identified. The police did not find an ID card or other items on her body that could prove the victim's identity.

The forensic doctor 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. She had had sexual intercourse before her death, but The medical examiner found no tadpoles in her body.

The hollow bricks tied to the victim's body were common hollow bricks used by locals when building houses. The reservoir at the time of the incident was located in a remote and desolate place. Outsiders had no guidance and rarely came here. Therefore, the police judged that, The murderer is most likely 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 and investigated all villages within a 3-kilometer radius to see if anyone used hollow bricks in their homes. Finally, they found a brick wall in Luojia Village that was the same as the hollow bricks tied to the victim. The murderer was very likely This is where the hollow bricks were taken.

But this place is connected in all directions. Anyone who is willing can easily remove a few hollow bricks. This can only confirm that the murderer has been here, and there are no other clues.

The top priority for the police is to first determine the identity of the victim.

In a murder case, if the source of the body is determined, the case is not far away from being solved.

It happened to be the Qingming Festival at that time, and the police thought that the woman came to visit the grave, so they visited and investigated people in Luojia Village and several surrounding villages.

But unfortunately, no villagers knew the victim, and there were no missing persons in the village during this period, so the case has reached a dead end.

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

If the source of the body cannot be determined, the suspect cannot be identified, and if the suspect cannot be caught, the case cannot be solved.

The case was shelved and became a worry 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. The criminal investigation team reviews this case every year and compares the victim's DNA, but there have always been no clues.

This case has been delayed for more than ten years, and the source of the body has still not been found.

Based on their understanding of the case, the police have not done nothing in recent years. They invited portrait experts from the province to restore the victim's face, trying to restore the victim's facial portrait through this method.

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

Currently, the only clue is the victim's DNA.

After reading the case, Li Xiang’s mobile phone also released the system task again:
[Task name: The case of corpses buried in Luoyang Reservoir]

[Mission Description: A 14-year-old unsolved case has touched the hearts of the Jinghai City Criminal Investigation Team. Old cases have been investigated every year, but there are very few clues. Under the principle that the murder case must be solved, the Jinghai police will concentrate their efforts and revisit the case again. When this case is brought up, as a newcomer of the Criminal Investigation Squadron No. [-], you are bound to take over this baton and investigate this case to the end. 】

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

[Task reward: experience +600, diamonds +3000]

"How is it? Li Xiang, what do you think of this case?" Mao Ji asked after seeing Li Xiang finish turning over the case.

Because in the previous case, Li Xiang put forward constructive suggestions, which allowed them to discover the truth that the murderers wanted to conceal 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. He hopes that Li Xiang can also play a certain role in this case. It is best to discover some new clues or ideas through the case.

"There are too few clues and the source of the body cannot be determined. Has our DNA database never been able to match the victim's family?"

"DNA data comparison is not a simple matter. Each human cell has 23 pairs (46) of paired chromosomes, which come from the father and mother respectively. The 23 chromosomes provided by each couple are mutually transmitted after fertilization. The pairing constitutes 23 pairs (46) of chromosomes of the child, and this cycle constitutes the continuation of life.”

"Since there are about 30 billion nucleotides in the human body making up the entire chromosome system, this makes comparison very difficult and the error is also very large. In order to reduce this error, we usually use the DNA data of the parents to compare together. Yes, 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 victim’s identity can be more accurately identified.”

Mao Ji knew that Li Xiang did not have a professional background, and that some basic DNA data comparisons were only fragments of hearsay knowledge. He thought that as long as he knew the victim's DNA data, he could quickly find the victim's family through big data, even if Even if they are relatives of the same clan, they can be found through DNA data comparison.

To a certain extent, there is nothing wrong with this statement, but it is really just theoretical and not based on reality.

There are many types of DNA comparison technologies. Different DNA detection methods have different accuracy, sensitivity and specificity. It is necessary to choose an appropriate comparison method to ensure the accuracy of the comparison.

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

In order to ensure the accuracy of the comparison, the police use parent comparison.

After 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 had always used the double-parent comparison method, which was the most accurate comparison, but they subconsciously ignored the single-parent factor.

"You are right, the victim may also be a single-parent family, but if the single-parent family is compared, the error will be larger."

"Let's try it. It's like treating a dead horse like a living horse."

Li didn't understand this, and he didn't know how big the error in the single-parent comparison data would be, but that didn't stop him from talking. Anyway, there were no other clues at the moment.

"Well, this is a direction that we can really try. Do you have any other opinions?"

Sometimes, they have always been in this system, and their ideas for solving crimes are somewhat solidified. The predecessors used the parent comparison method to confirm identity, and they have continued to use it to this day, and they have not considered single-parent comparison, which has a relatively large error.

Now that Li Xiang has brought it up, it breaks the thinking framework and is refreshing, so I want to hear if he has any other opinions.

"There is another question. The reservoir is located 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 we start the investigation from the murderer?"

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

Li Xiang nodded. It's true. If you can't even determine the source of the body, how can you find the murderer?
The murderer will not take the initiative to confess to the police when he sees the police coming. Without the support of evidence, no criminal suspect will take the initiative to confess to the police the crime he committed.

Of course, except those who surrender.

If the murderer wanted to surrender, he would not choose to dump the body.

Another day passed, Cao Gang summoned everyone to meet again on the case of corpses buried in Luoyang Reservoir.

"Li Xiang, have you finished reading all the cases?"

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

"The focus of our next work is still to return to this case. It has been more than ten years and we have been investigating it every year. But I hope everyone will not be discouraged and don't think that it has been more than ten years and it can't be solved anyway. We can deal with it. Only if we have a 200% attitude can we have the possibility of solving the case."

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

"Let's reorganize all the details of the entire case first."

Cao Gang took everyone to sort out all the circumstances of this case again, and also put forward his own opinions:
"The motive of the killing in this case has always been doubtful, and there are two speculations about the motive. One is robbery and murder. No property or mobile phone and other items were found on the victim. It is possible that the murderer killed and dumped the body after the robbery, but we are opposed to this Speculators believe that the Luoyang Reservoir is very remote and there are no locals to guide it. It is impossible for a foreign girl to come to this place. Even if she is traveling, she cannot completely avoid the sight of the locals."

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

"The opposition believes that this may be a love killing, and the murderer is probably a local. He knows the terrain of Luoyang Reservoir clearly, so he dumped the body after completing the murder. But the clues returned to the original point again. No villagers have seen this girl. Then Who did she come to Luoyang to see? And how did they meet? "

Cao Gang was thinking hard about this case. Every time a question arose, he would cling to the line and pursue it until the line was completely broken. Then he would sort it out again and discover new doubts. , and then traced it, constantly starting over and over again, constantly overthrowing and rebuilding.

This shows how much effort he put into this case.

"Everyone basically knows about this case. They all talked about it and brainstormed. Maybe the clues will be summarized during the discussion."

When Li Xiang listened to Cao Gang's views on the case and speculation on the motive of the murder, he always had a flash of inspiration. Every time he tried to catch it, he could never catch it. This made Li Xiang He was very distressed.

At this time, Mao Ji glanced at Li Xiang and saw that he had not stated the single-parent theory they discussed together yesterday, so he had to say for him: "Captain Cao, when Li Xiang and I discussed the case yesterday, he had a point of view that I I think it’s a good direction and I can give it a try.”

"Oh? What direction?"

"Currently, we use the method of double-parent verification to improve the accuracy of the victim's identity through DNA data comparison. However, 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 method. Let’s try the comparison method, I think I can give it a try.”

"Single parent? This is a direction, but the success rate of comparison cannot be guaranteed. However, this is also a non-solution. I can let the technology department try it."

After hearing Mao Ji's words, Cao Gang looked at Li Xiang in surprise. The fact that he could put forward this point of view showed that he was very flexible in his thinking in solving cases.

For old cases, you are not afraid of large errors or high difficulty, but you are afraid that there will be no clues and you will have nothing to do.

Although the accuracy of single-parent comparison is not high and the error is relatively large, it can screen out data samples with relatively high similarity through massive comparisons and then verify them one by one. The workload of doing so will increase exponentially.

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

"If we can lock down the victim's household registration location, the success rate in the national system comparison will be relatively high." Cao Gang thought for a moment. Although the success rate of single-parent comparison is not high, it does not mean that the success rate cannot be improved. rate, through geographical division, a large part of the errors can be screened out.

"This is a paradox. Only by knowing the identity of the victim can we know where her household registration is. But if we know her identity, we don't need to compare DNA data to confirm the identity of the victim." Su Jiayi heard what Cao Gang said , I feel that this sentence is equivalent to not saying that once I know the victim’s registered place of residence, the identity of the victim has already been known.

"There is a way, it depends on people, everyone should think about it."

Just now, when he heard Captain Cao's analysis of the motive for the murder, Li Xiang finally caught that glimmer of inspiration when he heard the victim's registered residence, and said: "Actually, if you want to know the victim's lifetime, It’s not difficult somewhere.”

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

"Huh? What can you do?"

When everyone heard that Li Xiang had a solution, they all immediately paid attention.

This is a case that has been pending for 14 years. What can you do?
(End of this chapter)