It can be considered Jiang Yuan's expertise to solve cold cases through fingerprints.

The plaque of a second-class hero is still hanging at the door, polished by his father day by day. After dealing with so many fingerprint cases, Jiang Yuan feels confident in comparing the blood fingerprint on this jacket.

This is a kind of self-confidence based on personal ability. First of all, the clarity of blood fingerprints is usually acceptable. Of course, the clarity of this fingerprint found on the jacket is slightly affected, but it is still much better than most latent fingerprints.

Secondly, although the fingerprint is only one-tenth the size and lacks a center, it has a fingertip. This condition is very personalized. In normal trace examination, if the fingerprint does not have a center or the center is blurry, it is directly abandoned because it is difficult to identify such fingerprints.

But for Jiang Yuan, as long as he can accurately judge the position of the center and the surrounding ridges are clear, he can do it. The success rate is only slightly lower than that of fingerprints without a center. If it is a recent case, the better the fingerprint condition, the easier it is to identify.

But after dealing with so many cold cases, a basic knowledge has long been established: the better the fingerprint condition, the less meaningful it is for cold cases. Anyone can identify such fingerprints, just like a dog that licks anyone it sees, its owner does not exist. Of course, the difficulty of the current fingerprint is also obvious. Jiang Yuan downloaded the fingerprint image to the computer and looked at it, but did not immediately start. At this time, a system message flashed in front of him: Task: Solve the suspicious case Task content: Solve the 405 Xu Hai case.

Jiang Yuan checked it and found that the 405 Xu Hai case was the one he had just selected. This way, he didn't have to worry about whether to choose another case if this case encountered difficulties. He just needed to focus on solving this case.

Jiang Yuan rubbed his hands, as usual, regardless of whether the fingerprint conditions were good or not, he started photoshopping. As the saying goes, "Photoshop three times, and the beauty won't stand still."

After photoshopping, the fingerprint is like a leader drinking Maotai, it will eventually reveal its true face. Jiang Yuan didn't need much, just 15 characteristic points on a complete fingerprint. He extracted 8 fingerprint points from one-third of the fingerprint, which provided a basis for comparison.

The old high-performance computer started rumbling. Wu Jun heard the sound and looked up, "Have you chosen a case?" Jiang Yuan said, "The 405 Xu Hai case."

"If you tell me about the body, I will know," Wu Jun stood up and lit a cigarette. Jiang Yuan went straight to the point, "The body was found beside the village road in Litang Township. When it was discovered, the body was about 8 meters away from the road, with trees and vines in between. The body was highly decomposed, with injuries on the abdomen and chest..."

"Ah, I know. The deceased was an individual clothing seller at the market," Wu Jun spoke with a sense of history. Jiang Yuan nodded and said, "I saw a blood handprint on his jacket, I want to compare it." "Using fingerprints, that's fine," Wu Jun said, but couldn't help adding, "This case is not easy to solve." "Where did it get stuck at that time?" Jiang Yuan was also curious.

Wu Jun didn't answer, but instead asked, "What do you think the nature of this case is?"

Jiang Yuan mainly focused on the fingerprints, but also had a general understanding of the case. After thinking for a moment, he said, "Robbery on the road? Then escalated to murder?" "But why would it happen 8 meters away from the road? There is a photo of the vegetation on the roadside taken at the scene. Take a look, it's very lush, and it's inconvenient to walk there."

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Jiang Yuan then flipped through the internal network photos, which were photos of homicide and cold cases, and the transcriptions were relatively clear. It can be seen that there are many plants two to three meters away from the village road. It is not possible to walk directly to 8 meters away. You have to squeeze in. If it was a knife-wielding robbery, it would be easy to go wrong. Of course, this part of going wrong may also be the reason for the escalation.

Jiang Yuan didn't fully understand, but he understood Wu Jun's meaning and said, "So, you didn't think it was a robbery on the road at first?" Wu Jun shook his head and said, "I thought it was, and many others thought so too. But the leaders didn't." "Why?"

"Because if it was a robbery on the road that led to murder, this case would be unsolvable." Wu Jun shrugged and sighed, "It makes sense. Back then, solving a case was still a three-step process: investigation, elimination, and breakthrough. In this remote area, turning it into a robbery and murder case would make it very difficult. Investigation, elimination, and breakthrough refer to on-site investigation, queuing for information gathering, and conducting sudden interrogations. This is a criminal investigation method based on a stable social relationship network.The household registration system established after the founding of the People's Republic of China greatly reduced the mobility of the population. Most crimes were committed by acquaintances, and through investigation, a satisfactory case-solving rate could be achieved. As for those who wandered outside, they were often referred to as "drifters" by the police system, frequently arrested for examination, interrogation, and repatriation. As a result, with the liberalization of social mobility, the operational capacity of the police system significantly declined, not to mention social security.

Wu Jun didn't tell Jiang Yuan one thing, that there were quite a few cases of roadside robbery back then, and the leadership's desire to solve them was not so strong.

Jiang Yuan curiously asked, "What did Captain Huang say back then?"

"He was the station chief at the police station at that time." Wu Jun paused for a moment, recalling, "I think it was this case that led to the change of the criminal police captain."

Jiang Yuan couldn't help but gossip, "Was the previous captain replaced because of this case?" "Probably. There were quite a few unsolved cases in those years."

Seeing that Wu Jun didn't want to discuss this topic, Jiang Yuan continued with the case itself, "So, you think the main problem with this case is the direction?" The victim's network of relationships had been thoroughly investigated with no results. Wu Jun shook his head, "You better look for fingerprints, that's the only way we can find something now."

Random crimes were hard to investigate back then, and even harder now.

In recent years, most of the solved cold cases have relied primarily on fingerprints and DNA, for similar reasons. Many clues that couldn't be found back then are even harder to find years later.

Jiang Yuan had hoped his master could provide more information. After all, many things are not written in the case files. What Wu Jun just mentioned, like the discarded direction of investigation, is one of those things not recorded in the files. However, it doesn't seem to be of much use for now.

Jiang Yuan didn't want to overthink it, he turned back to processing fingerprints, just like when he participated in the provincial fingerprint competition in Changyang.

Back then, no one was there to cooperate with you, it was simply about checking fingerprints. If you found a match, great; if not, you were out of luck. Half of the provincial fingerprint experts, who were at LV3 level, went home with no achievements. Jiang Yuan worked on a fingerprint until it was time to clock out. Wu Jun got up on time and asked Jiang Yuan, "Are you off work?"

"I'm working overtime." Jiang Yuan sighed, took out his phone, and sent a message to his father. Wu Jun smiled and said, "You should rest when you need to. Work and rest should be balanced."

"It breaks my train of thought." Jiang Yuan shook his head helplessly. During the provincial fingerprint competition, why were fingerprint experts more likely to succeed? Importance was one aspect, but also because they could focus on fingerprints without even having to go home.

Jiang Yuan dared not take this bloody fingerprint lightly. Returning to the state during the fingerprint competition was the most advantageous.