National Forensic Doctor

The police dog in the K-9 Unit of Ningtai County Criminal Police Detachment is named Dazhuang, a Rottweiler about four years old, strong in build, with a square and somewhat bald face, and a daily food standard of 45 yuan.

Compared to Heizi, the police dog from Longli County next door, Dazhuang is younger, more handsome, and stronger. However, because of its youth, it has no medals of merit on its chest, nor any community-building projects to its name. As such, its daily food allowance is 30 yuan less than Heizi's.

Dazhuang was unaware of this, so its mood remained very stable, and it showed simple happiness in its eyes upon seeing someone approach, with its tail floating lightly up and down.

"Dazhuang, sit!" The instructor seemed to think the dog wagging its tail was a bit undignified, and he came over from the other side of the wall, loudly reprimanding it.

Jiang Yuan looked in the direction of the voice and saw a tall, slender policewoman with long, thin legs, a straight back, and a slim waist turning around.

That instant... Jiang Yuan felt her face resembled that of a Rottweiler.

Her face was square, her brow bones prominent, her ears flat, and with almond-shaped eyes that were dark and tinged with brown, she looked somewhat worried.

"Li Li, can I borrow your kitchen to fry some rice? Do you have rice and eggs?" Wu Jun greeted her nonchalantly and took the opportunity to introduce Jiang Yuan, saying, "My apprentice, whose fried rice is quite delicious."

Li Li nodded politely at Jiang Yuan and then said, "Take a few eggs from Dazhuang's basket first; there's also meat in there. I'll have the food delivery replenish it this afternoon."

Upon hearing his name, Dazhuang sat up even straighter.

This wasn't Wu Jun's first time freeloading off Dazhuang. He laughed and responded, then asked, "Have you eaten? Join us for fried rice?"

"Sure," replied the policewoman Li Li readily, adding, "This will give me some time to cook for Dazhuang."

Engaged in conversation, the three then entered the kitchen of the K-9 Unit.

In terms of infrastructure, the conditions of the K-9 Unit were a bit worse than those of the detective team. The training ground for the police dogs was paved with hardened earth, and the walls surrounding the yard were made of the simplest red bricks and cement. Judging by the craftsmanship, it might have even been the dogs themselves who did the work.

The K-9 Unit's standalone kitchen consisted of nothing more than two flat houses. It likely dated back to the eighties or nineties. It could be said that Ningtai County, a small county under a prefecture-level city, had not achieved much during the era of competitive advantages.

The equipment inside the kitchen was complete, especially a large pot matched with a powerful stove that indeed looked very professional. However, Li Li pointed to an ordinary small stove next to it, saying, "Use that one, this side is for cooking Dazhuang's meal. How much meat should I cut?"

"No meat needed. I can only make vegetarian fried rice," Jiang Yuan said. "I need eggs, rice, some green onions, and oil. Should I make extra for the dogs to eat?"

"No need. Your fried rice is too nutritious, it can't be fed to the dogs."

Li Li then took ingredients from the refrigerator, dividing some rice for Jiang Yuan, tossing all the pig's trotters into Dazhuang's food bowl; dividing some eggs for Jiang Yuan, tossing all the chicken fillets into Dazhuang's food bowl; dividing some green onions for Jiang Yuan, tossing all the chopped broccoli, carrots, and cabbage into Dazhuang's food bowl...

The 45 yuan food standard for the police dogs was purely for food expenses, just like the 75 yuan for the meritorious dog Heizi and the 19.3 yuan for the rookies—it didn't include utilities such as water, electricity, gas, nor did it have to cover rent and labor costs. Therefore, it always seemed sufficient.

In comparison, Uncle Seventeen's egg fried rice, using one jin of rice for three servings, had a core cost of 1.2 yuan; half an egg had a cost of 0.5 yuan; with oil, green onions, seasoning, etc., 0.8 yuan was more than enough—the total cost for Jiang Yuan and his companions amounted to 2.5 yuan, with an average food expense of about 0.8 yuan per person...

However, Uncle Seventeen's Level 3 egg fried rice skill still made the meal look and taste wonderful.

In contrast, Li Li's cooking skills probably didn't even reach Level 1, a fact that could be guessed from the way Dazhuang sniffed and ate, and from Li Li's ravenous eating.

"Come by whenever you have time." Li Li, after gobbling down a few bites and taking half a glass of water in one gulp, patted her chest and said to Wu Jun, "Captain Wu, you've found a real talent this time. This is someone who can get things done. Can we borrow him for our unit? Look at Dazhuang, while other dogs scramble to eat, he seems to prefer leaving leftovers..."

"Staffing decisions are not up to me," Wu Jun said with a smile, quickly finishing his fried rice, stood up to pick his teeth, and said, "We've got work this afternoon, so you'll be left to clean up the dishes."

Wu Jun, now full and satisfied, called Jiang Yuan and left, moving as adeptly as a regular in the alleys of Sanlipu.

Looking back at Dazhuang, Jiang Yuan saw the dog calmly eating its 45-yuan meal. It was neither fast nor slow, its expression as serene as a car fueling itself.

"It's a bit odd for a female officer to name her own police dog Dazhuang," Jiang Yuan chatted as they walked.

Wu Jun chuckled and replied, "The name was probably given by her predecessor. They used to say, the first dog would be Dazhuang, the second Er Zhuang, and so on, all in tidy order."

"What about Er Zhuang? Out on duty?"

"Another dog came in, and the plan stopped," Wu Jun said with a shrug. "Captain Huang thinks that dogs are too expensive. One is enough, and the remaining money is better spent on hiring more auxiliary police."

Jiang Yuan thought about it and nodded in agreement.

At noon.

Jiang Yuan took a half-hour nap then got up, opened the fingerprints of the intentional injury case suggested by Xiao Wang in the morning, enlarged them, and began to study them closely.

The suspect left behind four consecutive fingerprints, which varied in terms of clarity and completeness. Deciding which fingerprint to focus on was the first consideration.

If completeness were to be the criterion, the little finger's print would likely be the most complete, but it also had the highest probability of not finding a match. This is because the chance of sampling the pinky for fingerprinting is the lowest; in many places, when issuing temporary residence permits and the like, it's the thumb or index finger that's used, as is the case with fingerprint time clocks.

Conversely, the index finger's print had the lowest completeness of the four fingerprints left by the suspect, and it was also the most deformed, with a wide spread of distortion.

Jiang Yuan pondered briefly before magnifying the image of the index finger and starting his analysis.

The marking difficulty of the little finger's fingerprint was relatively low. Of course, with Yan and Xiao Wang's skills, they probably still couldn't produce it since it was segmented from a cylindrical object. But since they had participated in fingerprint events in previous years, they should still be able to mark it correctly.

Therefore, the main reason the little finger failed to find a match was most likely due to an absence of records in the fingerprint database. It was a situation that could not be compensated for with technology.

On the other hand, the fingerprint most likely to have never found a match due to the technology itself was the index finger's print.

This fingerprint was severely deformed; one could imagine when the suspect was hitting someone with it, the grip must have been so strong that some of the fingerprint's ridges were squeezed together and others spread apart. It was as if a winding mountain road had been flattened by a giant's stomp.

Jiang Yuan still decided to open Photoshop and tried using "Edit-Transform" in Photoshop-CS5.

This step was akin to trying to restore a mountain road onto a flat surface, bringing it back to its original spacing and dimension.

Jiang Yuan first tweaked the image by 5% towards the center, felt it wasn't enough, adjusted it to 10%, then to 20%, before tweaking it back a little...

All these operations lacked a specific template to refer to. Ordinary fingerprints have a reference ridge width of 0.52 millimeters, but to be honest, this reference value had limited guiding significance, especially when making micro-adjustments by 1%. A number representing the average was not particularly meaningful.

Moreover, as the fingerprint had been segmented and photographed, and the technical skills of the crime scene police were not very strong, the different photos seemed to have angling issues. Usually, this wasn't a problem, but now the slight adjustments showed insufficient synchrony.

All these issues combined resulted in Jiang Yuan's repeated attempts failing to find a match.

As closing time approached, Xiao Wang came over again, conspiratorially leaning towards Jiang Yuan and whispered, "I checked, and this case has been involved in three fingerprint events without any results."

"The provincial ones?" Jiang Yuan paused his mouse.

"The first one was provincial, and the last two were municipal," Xiao Wang paused before chuckling. "The first time was still during the Horseshoe Mirror era, when there was no automatic fingerprint system. From the second time onward, they had one, but the results were the same."

The Horseshoe Mirror is a handheld magnifying glass, similar to a microscope head, which requires one to peer through one end with their eye. Traditionally used in fingerprint matching, document inspection, and even evidence searching, it could also be paired with a camera for photographing and extracting fingerprints. Before the advent of automated fingerprint identification technology, the Horseshoe Mirror was the most powerful tool in a trace examiner's arsenal.

The "Horseshoe Mirror era" Xiao Wang referred to was before the widespread use of automated fingerprint recognition technology. During that era's fingerprint events, fingerprint experts were no longer creatures sitting in front of computers with sparse hair; instead, they were creatures holding a Horseshoe Mirror in one hand and a fingerprint card in the other, also with sparse hair.

The matching of fingerprints relied largely on rich experience and memory.

Listened to Xiao Wang's words and nodded slightly. From his understanding, the current case fell into the category of those that had received relatively high attention but not the highest priority. With a serious injury case having lingered for over a dozen years and having received this level of criminal investigation resources, it was likely at the end of the line.

"I'll run it one more time." Jiang Yuan re-edited the characteristic points of the fingerprint he had just adjusted, then handed it over to the automatic fingerprint identification system to process.

Soon, a list of candidate fingerprints appeared on the right side of the screen.

Jiang Yuan and Xiao Wang looked through the 20 listed candidate fingerprints from top to bottom, unsurprisingly ending in disappointment.

"This is just chancing it now, I guess, even if there's a match, it won't be among the top ones." Xiao Wang had average technical skills, but he did seem to have some insight.

Jiang Yuan agreed, "Indeed, with such a large degree of adjustment, the order given by the system doesn't lend itself well as a reference. The 50th ranked fingerprint might be the suspect's..."

"If it doesn't work, let's just drop it. I'll look for other cases later." Xiao Wang sighed and started walking back.

Jiang Yuan held the mouse, moved it to the right a bit, and after thinking about it, he changed the number of fingerprints on the candidate inspection list to 150.

With this adjustment, the system now provided over seven times the original number of matching fingerprints with each query. And the further down the list, the lower the probability of a fingerprint being a match.

Jiang Yuan wasn't in a rush. Having made his decision, he patiently started examining the fingerprints.

Suddenly, a semi-transparent system prompt appeared in his field of vision—

Task: Find a match for the Liu Yu injury case to assist in solving the case.

Task Content: The victim needs consolation, the perpetrator needs punishment, and both need peace of mind. Help them.

Jiang Yuan couldn't help but chuckle. He had already prepared himself to grind through this intentional injury case, and now with the system's boost, he was even more equipped to settle in for the long haul.