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

"Strangulation marks?" Lu Chuan leaned closer to examine them. "Can you determine what type of rope it was?"

"The edges of the ligature marks are irregular, with small fiber residue, like a rough rope such as hemp rope." Yang Lin used tweezers to extract the fibers from the ligature marks. "We still need to go back and do a composition analysis. However, judging from the depth of the ligature marks, the murderer was very strong and ruthless."

In the victim's pocket, Yang Lin found a rusty one-yuan coin, dated 2015, with no other identification. "The victim had no cell phone, wallet, or ID card; either the murderer took them, or the victim simply didn't have them with him," Yang Sen speculated. "Combined with the beer bottle fragments and cigarette pack found at the scene, it's likely an inside job. The two had been drinking at the scene, then had an argument, and the murderer killed and buried the victim."

“It’s also possible that the murderer deliberately took the victim’s belongings to create the illusion of a robbery and murder,” Yang Lin added. “We found a set of footprints two meters east of the body. They were size 42, with the pattern of sneakers, a large stride, and a steady gait. They were likely left by a man and could be the murderer’s footprints.” He used plaster to fix the footprints in place. “There was soil accumulation around the edges of these footprints, indicating that the person who left them may have been standing on a slope, which is consistent with the terrain features of the ruins.”

The rain intensified, and water began to leak from the edges of the rainproof tent. Yang Lin and Yang Sen quickened their investigation. Behind the broken wall of the ruins, they discovered a patch of disturbed soil. The soil was darker and softer than the surrounding area, suggesting recent excavation. "This is likely the initial scene where the murderer buried the body, which was later unearthed by an excavator to another location," Yang Sen said, inserting a probe into the soil. "It's about 1.2 meters deep, the same depth as when the body was found."

In the turned-up soil, they found another cigarette butt, the same brand as the one in the tin cigarette box—"Double Happiness"—with obvious teeth marks on the filter. "The cigarette butt is very new, and its decomposition is much less than that of the body. It should have been left by the murderer when burying the body." Yang Lin put the cigarette butt into the evidence bag. "The saliva sample on it is very intact. The forensic department should be able to extract DNA from it."

At this moment, the head of the demolition office rushed over, holding a thick construction logbook. "Captain Lu, this is the construction logbook for area number three. We started clearing this area a week ago. This area had been sealed off before, and no one except construction workers was allowed to enter." The head wiped the cold sweat from his forehead. "We didn't know there would be a body buried here. If we had discovered it earlier, we would have called the police long ago."

Lu Chuan took the construction records and quickly flipped through them: "When the area was sealed off a week ago, did you check the site? Did you find anything unusual?"

"We checked it, and it was just a pile of ruins at the time. We didn't find anything unusual," the person in charge recalled. "However, three days before the lockdown, some villagers came here to collect scraps. It's possible that someone buried the body here at that time. This urban village was demolished three months ago, and most of the villagers have moved away. Only a few people are still lingering nearby."

This information clarified Lu Chuan's thinking: "The body was buried sometime between one week and three months ago, but we'll have to wait for the forensic examination to determine the exact time. Wang Shuai, take some people to visit the nearby villagers, focusing on checking missing persons cases from the past three months, especially men who match the deceased's characteristics. Also, contact the surrounding police stations to retrieve missing persons reports from the past three months and compare them."

At 5 PM, the rain gradually subsided, and Yang Lin and Yang Sen finally completed their preliminary on-site investigation. They meticulously organized the collected evidence, which included: a key, a tin cigarette box, two cigarette butts, a few strands of hair, a small amount of skin flakes, several blood-stained glass shards, multiple sets of footprint samples, and several different types of fibers. "Team Leader Lu, the on-site investigation is complete. All evidence has been sealed and is ready to be taken back to the technical department for testing," Yang Lin reported. "The body needs to be transported back to the branch as soon as possible for an autopsy to determine the cause and time of death."

Lu Chuan nodded, signaling his team to carefully lift the body onto the stretcher and cover it with a shroud. Watching the stretcher being loaded into the forensic transport vehicle, his heart sank. The deceased's identity was unknown, the killer's whereabouts were a mystery, surveillance footage was lacking, and the only clues were the key, the DNA on the cigarette butt, and two blurry sketches of suspicious individuals. But he knew that these seemingly insignificant clues would eventually connect to the truth.

"Yang Lin, Yang Sen, take the physical evidence back to the branch immediately and have the technical department prioritize testing it, especially the DNA in the cigarette butt and fingernail crevices, and the teeth marks on the key for comparison," Lu Chuan instructed. "Wang Shuai, you stay at the scene and cooperate with the local police station to conduct follow-up investigations. Report any developments immediately."

When Lu Chuan returned to the branch, the technical department had already begun testing the physical evidence. The team member in charge of DNA testing told Lu Chuan that the saliva sample extracted from the cigarette butt was successful and typing was underway, with results expected by tomorrow morning. The comparison of the key's teeth marks was also in progress; they had contacted locksmiths in the city to check for similar key models.

At 7 p.m., Wang Shuai called with an important clue: "Team Leader Lu, during our investigation, we discovered that a man named Zhang Dahai went missing three months ago. He is 35 years old, about 1.7 meters tall, and thin. He is a migrant worker who usually lives in a rented room in this urban village. His wife is the woman in the red coat who came to the demolition area to cry a few days ago; her name is Liu Fang."

“Zhang Dahai?” Lu Chuan immediately ordered his team to retrieve Zhang Dahai’s information. “His physical characteristics basically match the deceased’s. Contact Liu Fang immediately and have her come to the branch to identify the body. At the same time, extract her DNA and compare it with the hair between the deceased’s fingers.”

At 8 p.m., Liu Fang was taken to the Criminal Investigation Division. When she saw the body's clothes, she immediately collapsed to the ground, crying her heart out: "It's him! These are Dahai's clothes, I bought them for him, I even sewed the patches on the cuffs myself... How could he be here? What happened to him?"

Lu Chuan had his team help Liu Fang to the rest room and poured her a cup of hot water. After she calmed down a bit, he began to ask her about the situation. "Zhang Dahai disappeared three months ago. That morning he said he was going to work at the construction site, and he never came back. I reported it to the police, but I haven't heard anything since," Liu Fang said, choking back tears. "He was an honest man with no enemies. He just liked to drink and would occasionally play cards with his coworkers. If he lost money, they would argue."

"Has he made enemies with anyone? Or has there been anything unusual lately?" Lu Chuan pressed. (End of Chapter)