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

While Wang Shuai's team was stuck on the investigation of the means of transportation, Zhang Hui was leading his team through Xiangyang Village and surrounding towns, conducting detailed interviews about Zhang Tao's interpersonal relationships. According to the case analysis meeting's plan, they needed to look for potential sources of conflict in Zhang Tao's professional contacts and daily life. After all, the suspect's ability to lure Zhang Tao to the pasture under the pretext of "sheep disease" strongly suggested that he was familiar with Zhang Tao's profession or life.

"Besides treating local herders, which other villages and towns does Zhang Tao visit? Has he ever had any disagreements with his colleagues or villagers?" Zhang Hui asked the group of elderly herders sitting in the courtyard of Xiangyang Village Committee. One of the herders, Old Li, puffed on his pipe and thought for a moment before saying, "Zhang Tao is very skilled, and herders from the surrounding towns all love to see him, especially those from Dongfeng Village in the next town, where there are many sheep farmers. He goes there two or three times a month. As for disagreements, I think I heard him mention recently that he had a conflict with the veterinarian in Dongfeng Village, but he didn't go into details."

"The veterinarian from Dongfeng Village? What's his name?" Zhang Hui immediately pressed, his pen already poised to take notes. Old Li tapped his pipe: "I think his name is Li Bing, in his thirties. I heard he studied veterinary medicine with Zhang Tao for a few days before going solo. In the last two years, the two of them have had a bad relationship because of competing for business."

This clue caught Zhang Hui's eye, and he immediately decided to lead a team to Dongfeng Village. Dongfeng Village is about 10 kilometers from Xiangyang Village and is famous for its sheep farming. The village's veterinary station is located at the east end of the village. Zhang Hui found a staff member at the veterinary station, and when he mentioned Li Bing, the staff member's expression became somewhat subtle: "Li Bing? He's been on leave for the past few days and hasn't been to work. Many people in the village know about his conflict with Zhang Tao. They even had a fight at the village store last week, almost coming to blows."

"When was it last week? What did you argue about?" Zhang Hui pressed. The staff member recalled, "It was around August 10th, around 3 pm. Zhang Tao came to the village to treat Uncle Wang's sheep. Li Bing happened to be there too. I don't know how, but they started arguing. Li Bing said that Zhang Tao was 'stealing his business and cutting off his livelihood,' and even pushed Zhang Tao. Zhang Tao got angry, and the two almost came to blows. In the end, they were separated by the villagers who were watching."

To verify the details, Zhang Hui found Uncle Wang, a herdsman who was present at the time. Uncle Wang recalled: "That day, my sheep got pneumonia. I contacted Li Bing first, but he said he was busy, so I contacted Zhang Tao. As soon as Zhang Tao finished treating the sheep, Li Bing came and said that I 'looked down on him and would rather find an outsider than him.' He even argued with Zhang Tao, saying that Zhang Tao 'deliberately stole his clients.' Zhang Tao explained that 'the clients contacted me on their own initiative,' but Li Bing wouldn't listen and the argument got more and more heated. In the end, he even said, 'You wait, I won't let this go.'"

"Did Li Bing say anything more specific? Like what he was going to do to Zhang Tao?" Zhang Hui asked. Uncle Wang nodded: "When he got really angry, he said, 'If you keep blocking my path to wealth, I'll make sure you never get to treat sheep again.' At the time, we all thought it was just something he said in anger and didn't pay any attention. But now that I think about it, it was pretty scary."

After obtaining clues about the conflict, Zhang Hui immediately arranged for his team to conduct a comprehensive investigation into Li Bing. The first step was to investigate Li Bing's basic information: Li Bing, male, 36 years old, veterinarian of Dongfeng Village, 183cm tall, medium build, perfectly matching the on-site estimation of a suspect's height as 180-185cm; Li Bing owned a black agricultural tricycle with horizontal tire treads, consistent with the tire tracks found at the grassland scene; more importantly, Li Bing possessed a single-edged dagger, which he usually kept in his veterinary tool bag for dissecting animals, highly matching the forensic expert's deduction of "single-edged sharp weapon crime characteristics."

Next, they investigated Li Bing's whereabouts on the evening of August 15th. Zhang Hui found Li Bing's wife, who said: "Around 7 p.m. on the 15th, Li Bing said he was going to the west end of the village to treat the herders' sheep. He took his tool bag and went out. He didn't return until after 1 a.m. When he came back, he was covered in mud and his clothes were dirty. I asked him what happened, and he said, 'I accidentally fell.' I didn't ask any more questions."

"Did he drive a farm tricycle when he left? Did he take anything else with him?" Zhang Hui pressed. Li Bing's wife recalled, "He drove a tricycle and carried a black cloth bag. I don't know what was in it. When he came back, he didn't bring the bag back. I asked him, and he said, 'I left it at a herder's house. I'll go get it tomorrow.' I haven't heard him mention it since."

This information shocked Zhang Hui. Li Bing left home around 7 PM and returned around 1 AM, which highly coincided with Zhang Tao's time of death, which was between 10 PM and 11 PM. The mud on his clothes and the missing black cloth bag also corresponded to the clues of "mud traces" and "black cloth" found at the scene. Zhang Hui immediately arranged for his team to go to the "herdsman's house at the west end of the village" that Li Bing had mentioned to verify. The herdsman stated, "Li Bing didn't come to my house at all on the night of the 15th. My sheep were fine those days; they weren't sick." Li Bing's whereabouts were clearly a lie, further increasing suspicion.

Subsequently, Zhang Hui led a team to Li Bing's veterinary station and residence for investigation. In the tool cabinet of the veterinary station, a black canvas tool bag was found. There were a small amount of black fibers inside the bag, which were consistent with the fiber composition of the cloth that Zhang Tao was holding. In the drawer next to the tool bag, the single-edged dagger that should have been there was missing. Li Bing's wife said, "I used to see him put it here often. I haven't noticed it recently. I don't know when it disappeared."

Inside Li Bing's farm tricycle, team members extracted a small amount of black soil samples. Testing showed that the composition was completely consistent with the black soil found at the grassland site, and it also contained humus unique to the grassland. A few brown spots were also found at the bottom of the truck bed, which were identified as bloodstains. Although partially degraded due to the passage of time, they were still confirmed to be related to Zhang Tao's DNA. More importantly, a cigarette butt was found under the driver's seat of the tricycle. The brand was "Liqun," consistent with the brand of cigarette butts found near Zhang Tao. The saliva DNA on the cigarette butt was tested and found to be a perfect match for the "male skin tissue fragment DNA" extracted from under Zhang Tao's fingernails!
Furthermore, the team discovered in Li Bing's phone call logs that at 4:05 PM on August 15th, Li Bing used a temporarily registered phone number to call Zhang Tao. The call lasted 1 minute and 23 seconds, precisely the time Zhang Tao's wife mentioned when he received the "mysterious call"! Although Li Bing deleted the call logs, they were recovered through the operator's backend data. The phone number was registered at a business hall near Dongfeng Village, and the registrant information was anonymous, further confirming the hypothesis that "Li Bing lured Zhang Tao under the pretense of seeking medical treatment." (End of Chapter)