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

"Can tire tracks pinpoint a specific vehicle model? Besides auto repair shops, where else can we obtain lubricating grease?" Lu Chuan pressed, his finger lingering on the "small truck tire tracks" on the survey map, his brow furrowed slightly. Yang Lin shook his head: "Horizontal stripe tires are a common type for electric vehicles/motorcycles, used on at least tens of thousands of vehicles citywide; while vertical stripe tires can narrow it down to small trucks/SUVs, the specific brand and model still needs further database comparison by the technical department. Lubricating grease is a common industrial type; besides auto repair shops, construction sites and agricultural machinery stations can also obtain it, but considering Zhang Wanli's profession, it's more likely that people in the auto repair industry can obtain it."

Next, Wang Shuai reported the results of the investigation into the black sedan. The vehicle trajectory map on the screen marked the eliminated clues with red crosses: "We focused on investigating 15 surveillance cameras on the main roads and suburban roads around Beihe from 8 pm to 2 am on the night Zhang Wanli disappeared, six days ago. We found a total of 7 vehicles that matched the characteristics of a 'black joint venture sedan with silver trim.' One of them belonged to logistics driver Liu Wei, which was the one we investigated earlier. However, after repeated verification, Liu Wei was indeed delivering documents in Xiwangcun that night. There is supermarket surveillance footage and colleagues' testimonies to corroborate this. Although the characteristics of the vehicle, such as the crooked right rearview mirror and abnormal engine noise, are consistent with the description of the person who reported the case, there is no connection with Zhang Wanli. He has been completely ruled out as a suspect."

"What are the results of the investigation of the other six black sedans? Have you found any vehicles related to the 'suburban customer' or Tongda Auto Repair Shop?" Lu Chuan asked. Wang Shuai's tone carried a hint of regret: "Of the other six, four are private cars belonging to villagers in the surrounding area. They were all active in the village that night and had no record of going out. The other two are ride-hailing vehicles. Their routes that night were all far from the Beihe area, and their passenger information is traceable, so they have been ruled out. At present, the black sedan clue is indeed a distraction. The vehicle used by the suspect to dispose of the body should be a small truck and an electric vehicle/motorcycle, not a black sedan."

Wang Shuai added, "However, when we were checking the surveillance footage in the suburbs, we found a suspicious situation. At 10:15 p.m. six days ago, the surveillance footage on the suburban road upstream of the Beihe River captured a small truck without license plates driving by. The truck bed was covered with a black tarpaulin, and the speed was significantly slower than normal. The driver was wearing a baseball cap and a mask, so his face could not be identified. The truck was traveling in the same direction as the tire tracks on the rocky beach upstream, but because it had no license plate, we could not track its subsequent trajectory. This may be the vehicle used by the suspect to transport the body."

Zhang Kai then reported the core conclusions of the autopsy. The autopsy report projected on the screen clearly displayed the key data: "The deceased, Zhang Wanli, male, 46 years old, 175cm tall, was determined to have died between 0:6 and 3:6 AM six days ago based on three dimensions. The first dimension is the characteristics of decomposition: the skin all over the body was in the state of 'washing hands,' the putrefactive venous network in the chest and abdomen was distributed in a tree-like pattern, and the greenish tinge in the lower right abdomen spread to the waist. Combined with the water temperature of 15℃ in the Beihe River, it is estimated that the decomposition process has lasted for 5-7 days. The second dimension is entomological evidence: the midge larvae extracted from the hair and clothing crevices were in the 3rd instar, and the water fly pupae would take 3-5 days to mature at the current water temperature, which cross-validates with the characteristics of decomposition. The third dimension is the stomach contents: only brownish pasty substances remained in the intestines, with no undigested food, which is consistent with the emptying state 8-12 hours after death, and matches the family's statement that 'they ate at home at 7 pm six days ago,' further narrowing down the time range of natural death."

"The fatal injury and key related clues are the focus. Is there any information that directly points to the murder weapon or the suspect?" Lu Chuan pressed, his finger hovering over the "Injury Analysis" page of the report. Zhang Kai switched to the injury photos, his tone serious: "The fatal injury is a mechanical asphyxiation injury to the neck. There is a 1cm wide band-shaped indentation around the neck, with cotton fiber residue at the edge of the indentation. Tests show that the material is consistent with the rags commonly used in auto repair shops, suggesting that the weapon used was a cotton rag from an auto repair shop. There is obvious bleeding in the neck muscle tissue corresponding to the indentation, a fracture of the greater horn of the hyoid bone, and no mud or sand in the trachea, proving that the death was caused by strangulation before death, ruling out drowning."

He added, "Two other key findings require special attention: First, a 3×4cm blunt force injury on the left temporal region. A small amount of gray cement powder was extracted from the wound cavity, which is consistent with the powder composition found on the upstream rocky beach. This indicates that the blunt force used by the suspect, such as a stone or cement block, came from the vicinity of Beihe, and the attack occurred before strangulation, possibly to control Zhang Wanli. Second, a brass fragment embedded in the left wrist. After testing, it was found to be made of the same material as the 'repair watch' described by Zhang Wanli's wife. The polishing marks on the edge of the fragment prove that the watch strap broke and embedded itself in the skin. Combined with the fact that the watch body was not found at the scene, it is speculated that it was torn off by the suspect during the struggle and taken away, and may have been destroyed."

Zhang Hui's final report included the deceased's identity and related clues. A diagram of Zhang Wanli's social relationships appeared on the screen, with red lines highlighting "wage dispute" and "last customer": "Through visits to Tongda Auto Repair Shop and Zhang Wanli's family, we have identified two key conflicts. The first is a wage dispute. The repair shop owner, Wang Qiang, owes Zhang Wanli three months' wages, totaling 12,000 yuan. Zhang Wanli had repeatedly demanded payment. Six days ago, on the morning of the day he disappeared, the two had a heated argument at the shop. Zhang Wanli threatened, 'If you don't pay my wages, I'll report you to the labor department and expose the shop's tax evasion.' Three colleagues witnessed the argument. Wang Qiang said at the time, 'If you dare to report me, you'll be in big trouble.'"

“The second category is the ‘suburban customers’ we last contacted,” Zhang Hui paused, then pulled up the repair records of Tongda Auto Repair Shop. “We checked the shop’s repair invoices for the past month, and there was no record of ‘suburban truck repair’ six days ago. The ‘customer’s urgent repair’ mentioned by Zhang Wanli’s wife is likely an excuse fabricated by the suspect to lure Zhang Wanli to the suburbs. In addition, Wang Qiang said that ‘Zhang Wanli took on private jobs and may have offended other customers,’ but we have not found any records of such private jobs yet. We need to further investigate Zhang Wanli’s private communications and transfer records.”

"Has Wang Qiang's whereabouts been verified? Does he own a small truck or electric vehicle/motorcycle?" Lu Chuan asked. Zhang Hui nodded: "We've arranged for team members to conduct a preliminary verification: Wang Qiang owns a silver small truck, registered three years ago. The tire model matches the longitudinally striped tires found upstream. However, Wang Qiang claims he 'stayed home with his family and didn't go out' six days ago, and his wife's testimony matches his, so we can't verify the truth of this at the moment. He also owns a black electric vehicle with horizontally striped tires, matching the tire model found downstream. However, the electric vehicle was parked in the auto repair shop's yard six days ago, as evidenced by surveillance footage, and it hasn't been used. In addition, Wang Qiang has recently been experiencing cash flow difficulties at his factory, accumulating nearly 100,000 yuan in debt. There is a motive for him to commit the crime out of fear of being reported, but we currently lack direct evidence." (End of Chapter)