Attending ex-girlfriend's wedding, arresting the groom's officer on the spot

Yang Sen nodded, and together with Yang Lin carefully put away the plaster samples, the fiber-sealed bags, and the black debris-sealed bags, organized the investigation records, and prepared to leave the unfinished building complex. "Today, we expanded the investigation area and made two important discoveries: first, tire tracks and fibers and debris extracted from the surrounding area on the third floor of Building 2; second, drag marks and gray fibers found in the open space around Building 3. Although these clues cannot directly point to the murderer, they at least provide direction for solving the case."

“That’s right, but we can’t overestimate the value of these clues.” Yang Lin analyzed as they walked. “The plaster sample of the tire tracks needs to be compared with the tire treads to determine the car model; the fibers need to be tested to confirm whether they match the deceased’s coat; the composition of the black debris also needs to be tested to determine whether it is related to the tires. Moreover, even if the tire tracks were left by the old black sedan that Lao Zhou saw, without the license plate number and owner information, it will be difficult to track down the suspect.”

“Identifying the deceased remains the biggest challenge,” Yang Sen sighed. “Currently, all we know is that the deceased was likely a scavenger who frequented unfinished buildings, aged 40-50, wearing a gray coat, but had no identification, and no one knows his name or address. If the technical department can find more relevant information through fibers or debris, it might help determine the deceased’s identity.”

The two men reached the entrance of the unfinished building complex and saw Lu Chuan still waiting outside the police cordon. "Captain Lu, we've expanded the search area and found something!" Yang Lin quickly stepped forward and reported the findings, "We found a tire track on the third floor of Building 2, 10.2 centimeters wide and 50.5 centimeters apart, and extracted a plaster sample; we also found 3 fibers and some black debris around it; we found drag marks in the open area around Building 3, and extracted 5 gray fibers, which are suspected to match the fibers from the deceased's coat."

Lu Chuan took the investigation record, examined it carefully, and said, "Very good! These clues are very important. Take the samples back to the branch immediately and have the technical department test them overnight—prioritize testing whether the fiber material matches the deceased's coat, compare the tire track samples with the tire tread pattern, and analyze the composition of the black debris. Also, sort through these clues and see if we can make a preliminary deduction of the suspect's crime route."

“Our initial deduction is that the suspect may have driven an old black sedan to transport the body to the unfinished building, parked it near Building 2, and then dragged the body to the third floor of Building 3 to dump it. However, there are still a few questions that have not been resolved.” Yang Lin explained the questions that he had discussed with Yang Sen one by one: “First, the tire tracks are on the third floor of Building 2, which is inaccessible to the vehicle; second, the drag marks and tire tracks are not consistent; and third, the primary crime scene has not been identified.”

Lu Chuan nodded, pondered for a moment, and said, "These questions need to be further analyzed after the technical department's forensic report. The tire tracks may not have been left by a car, but by other wheeled vehicles, such as an electric tricycle or a handcart; the drag marks are discontinuous, which may indicate that the suspect changed routes midway, or that the body did not fully touch the ground when it was being transported. The most important thing right now is to get the forensic results as soon as possible, while waiting for feedback from Wang Shuai's investigation, and striving to determine the identity of the deceased and find clues about the suspect as soon as possible."

At 11 p.m., Yang Lin and Yang Sen returned to the Criminal Investigation Detachment with the extracted samples and immediately sent them to the Technical Section, instructing the technicians to test them overnight. "Although we have made new discoveries, we still haven't confirmed the identity of the deceased, and many details need to be identified before they can be clarified." Yang Sen sat on a bench outside the Technical Section, rubbing his sore shoulders. "It feels like we are just one step away from the truth, but that step is very difficult to take."

Yang Lin sat down beside him, looking at the lights on in the technical department, and said, "That's how solving cases is; it's never smooth sailing. We've already found tire tracks and fiber traces, which are real clues. As long as the technical department can detect valuable information, such as confirming the car model or that the fibers match the deceased's coat, we can further narrow down the search. Moreover, Wang Shuai is going to visit the shelter and the scrap metal recycling station tomorrow; maybe he can find someone who knows the deceased and confirm their identity."

"I hope so," Yang Sen sighed. "The deceased was a scavenger, highly mobile, with simple social relationships, so it's indeed not easy to confirm his identity. But as long as we don't give up and sort through the clues little by little, we'll eventually make a breakthrough."

The two sat on the bench for a while when a staff member from the technical department came out with a preliminary test report: "Brother Yang Lin, Brother Yang Sen, the preliminary test results are in—the five gray fibers extracted from around Building 3 are made of cotton, and their material and color are completely consistent with the fibers of the deceased's coat; the three fibers extracted from Building 2 are polyester fibers, black in color, and unrelated to the fibers of the deceased's coat; the black fragments are preliminarily identified as rubber components, possibly produced by tire wear, but the specific composition still needs further testing; the plaster sample of the tire tracks is being compared with the tire treads, and the results are expected tomorrow morning."

"Great! The gray fibers match the deceased's coat, which means the drag marks were indeed left by the suspect when dragging the deceased!" Yang Lin stood up excitedly. "The black polyester fibers may be from the suspect's clothing, and the rubber fragments are from tire wear. These are all important clues! Tomorrow, when the tire tread comparison results come out, we will be able to determine the source of the tire marks."

Yang Sen also stood up, a smile appearing on his face: "Although the identity of the deceased and the suspect have not yet been confirmed, it at least proves that our investigation direction is correct. We will continue to follow up on the identification results tomorrow, and at the same time cooperate with Wang Shuai's visits. I believe we will have a new breakthrough soon."

At 1 a.m., Yang Lin and Yang Sen finished compiling the preliminary test report and returned to their office. Although exhausted from a long day, their hearts were filled with hope—tire tracks, fiber traces, rubber fragments—these clues were like pieces of a puzzle, slowly piecing together the outline of the case. They knew that as long as they continued to follow these clues, cooperating with technical identification and interviews, they would eventually identify the deceased, find the killer hiding in the shadows, and give the victim justice.

Meanwhile, in the Criminal Investigation Division's office building, many offices were still lit up—technical staff were working through the night to test samples, Wang Shuai and his team were organizing interview records, and Lu Chuan was studying case materials. Everyone was working hard to solve the case, using their dedication and professionalism to safeguard the justice and peace of this city.

After the on-site investigation was completed, at 11:30 p.m., the body from the unfinished Huijiayuan building was carefully carried into the forensic autopsy room of the Criminal Investigation Detachment.

The forensic pathologists are about to begin the autopsy. (End of Chapter)