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

After the third layer of plastic sheeting was removed, the victim's head and upper limbs were fully exposed. The victim was an adult male, preliminarily estimated to be between 35 and 45 years old, approximately 175 cm tall, with short hair, a pale complexion, cyanotic lips, and closed eyes. There were no obvious external injuries to the head. The upper limbs were placed naturally at the sides of the body, with the hands clenched into fists, and a small amount of dust and fibers were found under the fingernails. "The clenched fists of the victim's hands may have been an instinctive reaction during the stabbing," Yang Lin observed. "Taking samples of the fibers and dust from under the fingernails may reveal traces of the suspect."

Yang Sen carefully extracted samples from under the deceased's fingernails using tweezers, placing them into evidence bags labeled "Deceased's Fingernails-001" and "Deceased's Fingernails-002" respectively. The two then conducted a detailed examination of the deceased's clothing, finding a key in the pocket of his trousers, but no other items; and a crumpled tissue in his shirt pocket, with no obvious marks.

"Focus on examining the wound on the victim's chest to confirm the number of stabs and their depth," Yang Lin said. The two carefully examined the skin corresponding to the tear in the victim's shirt. A distinct wound was visible, located on the left side of the chest between the 4th and 5th ribs. The wound was spindle-shaped, approximately 5 centimeters long and 1.5 centimeters wide, with clean edges and one blunt and one sharp angle, consistent with the characteristics of a single-edged dagger stab. "The wound edges show no epidermal abrasion or bruising, indicating it was caused by a single stab with a sharp object, without signs of repeated stabs," Yang Lin analyzed. "The sharp side of the wound corresponds to the sharp edge of the dagger, and the blunt side corresponds to the back of the dagger, further confirming that the murder weapon was indeed that single-edged dagger."

Yang Sen used his camera to take close-up photos of the wound, recording its shape and location from different angles. "Based on the location and shape of the wound, combined with the previously discovered splattered blood, we determined that this wound was fatal, and the stab wound must have reached the heart, causing the deceased to die from hemorrhagic shock," Yang Lin said. "However, the specific cause of death and the depth of the stab wound need to be confirmed by a subsequent autopsy by a forensic doctor."

During the investigation, the two investigators also found a small number of fiber samples on the plastic sheeting and discarded wooden boards around the body. The samples were black, gray, and blue, and their colors did not completely match the colors of the deceased's clothing and the plastic sheeting. "These fiber samples may have come from the suspect's clothing. They will be collected and sent for testing and comparison," said Yang Lin. He used tweezers to collect fiber samples from different locations, labeled them, and sealed them.

At 10:50 AM, the initial investigation of the core scene was basically completed. The two began a second review of the scene to ensure that no traces or physical evidence were missed. Yang Lin re-examined the retrieval of key evidence such as bloodstains, footprints, a dagger, and a wallet, while Yang Sen organized the scene investigation records and the photos and videos taken, checking for any omissions or errors.

“现场共提取到滴落血迹4处、擦拭血迹1处、血泊血迹1处、刀刃血迹1处、钱包血迹1处，共计8份血迹样本；提取到完整指纹2枚（匕首刀柄1枚、主入口门框1枚）、残缺指纹纹线碎片3处；提取到足迹石膏模型6个（42码胶底鞋印4个、41码皮鞋印2个）；提取到纤维样本5份、死者指甲缝样本2份；扣押作案工具单刃匕首1把、死者钱包1个、钥匙1枚。”杨林汇总勘查结果后说道，“所有物证均已编号、拍照、密封，后续送往技术科进行DNA分型和指纹比对。”

Yang Sen added: "The on-site investigation has determined the following key information: First, the murder weapon was a single-edged dagger, and the victim died from a stab wound to the chest; second, there were footprints of two adult males at the scene, the size 42 rubber-soled shoe print belonged to the suspect, and the size 41 leather shoe print belonged to the victim; third, the victim's wallet was ransacked and valuables were missing, indicating a motive of murder for financial gain; fourth, the suspect entered through a gap in the fence on the northwest side of the unfinished building in the northern suburbs, went up the west staircase to the core scene on the 3rd floor, and fled along the same route after committing the crime; fifth, no identification items of the victim were found, and the victim's identity cannot be confirmed at this time."

At 11:10 AM, the on-site investigation was completed. Yang Lin and Yang Sen reported the results to Lu Chuan, who immediately made arrangements: "First, the technical department should immediately test the extracted bloodstains, fingerprints, fibers, and other samples to obtain the suspect's DNA information and fingerprint characteristics as soon as possible; second, arrange for team members to visit homeless people in the vicinity of the scene to find witnesses and find out if any strangers have been active near the unfinished building recently; third, use the keys and wallet found at the scene as clues to investigate the surrounding residential areas and shops to try to confirm the identity of the deceased; fourth, retrieve the surveillance footage around the unfinished building in the northern suburbs, focusing on investigating the people and vehicles that entered and exited the gap in the northwest fence before and after the incident (from 8 PM last night to 9 AM this morning)."

Subsequently, the technical support staff carefully loaded all the collected physical evidence into a vehicle and sent it to the technical department for examination; the investigation team began interviewing homeless people in the surrounding area and went to the surrounding communities and shops to investigate clues about the deceased's identity. Yang Lin and Yang Sen remained at the scene to assist the technicians in the final protection and marking of the scene to ensure that the subsequent forensic autopsy and supplementary investigation could be carried out smoothly.

At this moment, sunlight streamed through the hole on the north side of the third floor, illuminating the body and reflecting the bloodstains and scattered evidence on the ground. The once quiet, unfinished building felt especially somber because of this murder. Although the victim's identity and the suspect have not yet been confirmed, Yang Lin and Yang Sen, through meticulous on-site investigation, have collected a large amount of valuable trace evidence, laying a solid foundation for subsequent case investigation. The two men knew that every trace might hold the truth of the case, and only by rigorously analyzing every clue could they bring the murderer to justice as soon as possible and bring justice to the deceased.

While Yang Lin and Yang Sen were conducting a detailed investigation inside the unfinished building, Lu Chuan had already set up a temporary command post outside the site and assigned Wang Shuai, the deputy captain of the investigation team, to lead four investigators to form an external investigation team to simultaneously advance the surrounding area investigation.

"Wang Shuai, your core task is to investigate the activities of people in and around the abandoned building, focusing on the homeless residents, verifying their identities and inquiring about their recent whereabouts; at the same time, visit surrounding villages, supermarkets, and small shops to find witnesses before and after the incident and collect clues about suspicious individuals." Lu Chuan pointed to the location map and emphasized seriously, "This area is quite special. The abandoned building has been abandoned for two years, and the surrounding surveillance coverage is almost zero, making it difficult to collect evidence. You must be meticulous during your visits and not overlook any clues." (End of Chapter)