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

“I agree with Captain Lu’s assessment,” Yang Lin continued. “The key now is to find the ‘mysterious caller’ who lured Zhang Tao and the ‘suspicious figure’ on the road west of the grassland. Judging from the traces at the scene, the suspect may have used both a motorcycle and a tricycle—the motorcycle was used to travel back and forth to lure Zhang Tao, and the tricycle was used to transport the tools used in the crime or to clean up the traces; the oil residue in the tire tracks and the mud in the shoe prints can all be used as evidence for investigation, especially the nearby auto repair shops and agricultural machinery stations, where someone may have seen a vehicle or person matching the description.”

Wang Shuai offered additional suggestions: "We can expand the scope of the investigation into the 'suspicious figure' by combining it with the city's surveillance cameras to track his whereabouts after 11:30 p.m. on the 15th; at the same time, we should focus on investigating the 'single-edged sharp weapon,' visiting hardware stores and supermarkets around the grassland to retrieve sales records from before and after the 15th and look for people who have purchased similar daggers or knives; in addition, although Zhou Ming's tricycle has an alibi, the tire tread pattern matches the tracks at the scene, so we need to further test the mud composition of the tires to see if it is related to the black soil of the grassland."

"Based on the autopsy results, the suspect's modus operandi was somewhat premeditated—luring the suspect in advance, carrying a weapon, cleaning the scene and taking the shoes, and emptying his pockets. However, the chaos during the struggle suggests that he may not be a repeat offender. Although he had strong counter-surveillance awareness, he still left behind clues such as skin tissue fragments and fibers," Zhang Kai added. "The DNA from the skin tissue fragments under his fingernails is currently the most direct evidence. I suggest expanding the database comparison scope to include not only people with criminal records, but also herders and veterinarians around the grassland, and even people with recent disputes. This might lead to a breakthrough."

Zhang Hui suggested: "We can re-examine Zhang Tao's call records—the 'mysterious call' at 4 pm on the 15th was likely made by a number that the suspect used temporarily. We need to investigate newly registered mobile phone numbers and anonymous mobile phone numbers in the surrounding area that day. At the same time, we should further examine Zhang Tao's tool bag. Although only fabric fragments were found at the scene, items such as stethoscopes and syringes in the tool bag may have been taken away by the suspect. We should also investigate the surrounding garbage dumps and waterways, where we might find discarded tools and extract the suspect's fingerprints or DNA."

After listening to everyone's analysis, Lu Chuan drew four core investigation directions on the whiteboard, circling the keywords "mysterious caller" and "suspicious figure" in red: "Group 1, led by Wang Shuai, is responsible for tracking the 'suspicious figure's' movements in the city, working with traffic and public security departments to review surveillance footage in the city after 11:30 pm on the 15th, and simultaneously checking surrounding shops for clues related to the 'single-edged sharp weapon'; Group 2, led by Zhang Hui, is responsible for in-depth investigation of the source of the 'mysterious caller's' number, checking mobile phone numbers around the grassland around the 15th." The first group, led by Yang Lin, conducted registration and call record checks, and also tested the soil on Zhou Ming's tricycle to verify its connection to the crime scene. The second group continued to follow up on the technical department's DNA comparison of fingernail crevices and fingerprints from mineral water bottles, while also searching the surrounding garbage dumps and waterways for Zhang Tao's tool bag or the murder weapon. The third group contacted telecommunications companies and veterinary industry associations to investigate Zhang Tao's professional connections and identify other potential adversaries, especially those who had recent disputes with Zhang Tao and whose height matches the suspect's description.

He paused, then emphasized, “'Mysterious calls' and 'DNA matching' are the most crucial breakthroughs right now—finding the caller will allow us to directly identify the suspect; matching the DNA will allow us to quickly confirm the identity through the database. All teams must cooperate closely, share information, and report any leads immediately, striving to apprehend the murderer in the shortest possible time and give Zhang Tao's family an explanation.”

Sunlight streamed through the blinds, casting long, thin patches of light on the conference table. Zhang Hui pasted composite sketches of the "mysterious caller" and the "suspicious figure" onto the whiteboard. The expressions of the two figures in the sketches were blurred, yet they represented key targets in solving the case. "We will definitely find clues as soon as possible and bring justice to Zhang Tao," Zhang Hui said firmly, and everyone present nodded in agreement.

As the meeting adjourned, Lu Chuan watched the busy figures of everyone, knowing in his heart that the case had reached a crucial stage. By focusing on the three clues—the "mysterious phone call," "DNA comparison," and "vehicle"—the truth behind Zhang Tao's murder would eventually be revealed, and the hidden killer would be brought to justice. In the corridor of the Criminal Investigation Division, footsteps echoed, each person carrying a clear goal, moving towards the truth—the tragedy that occurred in the grassland was about to be exposed.

After the case analysis meeting, Wang Shuai and his team immediately began tracking down the vehicles. As planned in the meeting, they not only continued to investigate motorcycles and agricultural tricycles around the grassland, but also expanded the search to the city and surrounding towns, focusing on vehicles that met the criteria of "black body, horizontal striped tires (tricycles), vertical striped tires (motorcycles), and having black soil or engine oil residue from the grassland".

"Let's start by checking the motorcycle repair shops and agricultural machinery stations in the city," Wang Shuai said to his officers Xiao Li and Xiao Zhang from inside the police car. "The suspect's vehicle may be damaged or need to be cleaned of mud. The repair shops and agricultural machinery stations might have clues. In addition, we should also check the used car market in the city to prevent the suspect from selling the vehicle and destroying evidence."

The first stop was "Chengxin Motorcycle Repair Shop" in the eastern suburbs of the city. After seeing the photos of the vehicles shown by the police officers, the shop owner, Mr. Liu, frowned and recalled: "Black motorcycle, longitudinal striped tires? I've repaired a few black motorcycles recently, but the tire treads are all horizontal, I've never seen longitudinal ones. As for farm tricycles, a few days ago a villager came to repair a black one, the tires had horizontal stripes, but there was no mud in the cargo bed. He said he had bumped into a stone while hauling fertilizer, and drove away after the repair without leaving any contact information."

Wang Shuai asked Master Liu to retrieve the repair records, which led to the repair information for the black farm tricycle—the owner was registered as "Li Bing," living in the western suburbs of the city, in the opposite direction from the grassland. The team members immediately rushed to Li Bing's house and saw the tricycle parked in the yard. The vehicle was clean, and although the tire treads were horizontal stripes, the mud on the tires was tested and found to be yellow soil from a construction site in the city, completely different from the black soil of the grassland. Li Bing also provided an alibi for the night of August 15th—he was on duty at a construction site in the city that night, as confirmed by a colleague, thus eliminating suspicion.

Over the next two days, Wang Shuai's team inspected 23 motorcycle repair shops, 18 agricultural machinery stations, and 6 used car markets in the city and five surrounding towns. They registered a total of 47 motorcycles and 32 agricultural tricycles that matched the "black body" characteristic, and each vehicle underwent meticulous inspection and information verification. (End of Chapter)