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

“The deceased’s order list for September 10 shows that the last order was for Unit 2, Building 3, Anju Community, with an agreed delivery time of 7:30 pm,” he tapped the red dot on the route map with his fingertip. “From the delivery address to the parking lot, it’s about a 5-minute walk, which passes right by the water tank.” He pulled up Zhang Guojun’s attendance record, and the pickup record for September 10 was blank. “The Lalamove platform’s location data shows that his cell phone signal disappeared in the community after 8:15 pm that night, which is highly consistent with the time of death.”

“The key suspect is Li Qiang,” Zhang Hui suddenly circled a name in red pen, and a photo of the building materials store owner popped up on the screen. “Male, 38 years old, 176 cm tall, had a dispute with Zhang Guojun over a 9 yuan delivery fee, and threatened Zhang Guojun on the phone last week.” He pulled up Li Qiang’s vehicle information. “He owns a black sedan, and his driving trajectory from 7 pm to 11 pm on September 10th was around Anju Community, which presents a window of opportunity for the crime.”

The air in the conference room seemed to freeze. Sparrows hopped and chirped outside the window, their sounds unable to penetrate the heavy atmosphere. "Now there's a crucial question," Lu Chuan said, tracing two lines on the table with his finger, "Why did the murderer choose to dispose of the body in a water tank? Was it a spur-of-the-moment decision or premeditated?" He looked at Yang Lin, "Were any clues found at the scene that could prove it was the primary crime scene?"

Yang Lin shook his head: "There was only a small amount of drowning fluid in the water tank, and no signs of struggle. Combined with the absence of drowning fluid in the victim's stomach, it's determined that the body was disposed of after death. However, the primary crime scene has not yet been identified. There were small amounts of blood in the fire escape and underground parking garage, but the amount was too small to determine the crime scene." Zhang Kai suddenly added: "The victim's palms showed signs of resistance, and DNA from the skin tissue under the fingernails is being tested. If it matches a suspect, it will be a significant breakthrough. The finger pressure marks on the neck indicate that the perpetrator may have been wearing a ring on their right hand, with a serrated pattern, which is an important individual characteristic."

Li Bing suddenly put down his pen, his chair scraping half an inch off the floor. "I'm inclined to believe it was a crime of passion stemming from a dispute over shipping fees," he said, pointing to Zhang Hui's route map. "Li Qiang may have argued with Zhang Guojun while receiving the goods, which led him to decide to kill him. Afterwards, to cover up his crime, he used his familiarity with the neighborhood to throw the body into the water tank. The water tank's location was concealed and could delay its discovery." He analyzed, "The wrench and chain found at the scene were probably tools that Li Qiang borrowed or stole from the property management."

Xiao Lin raised a different opinion: "If it was a crime of passion, why would he be carrying a suitcase?" He pointed to the surveillance screenshot of Wang Shuai, "The man in the surveillance footage is carrying a suitcase, which makes it seem like a premeditated crime. Also, Li Qiang is 176 cm tall, which differs from the estimated 178-183 cm at the scene." Zhang Kai nodded in agreement: "The strangulation was fluid, and the finger marks were evenly distributed, indicating that the suspect has a certain strength and experience, and doesn't seem like a first-time offender. If the skin tissue under the fingernails can be confirmed as belonging to the murderer, it will directly confirm his identity."

Lu Chuan suddenly made a decision: "We'll split into four groups to conduct the investigation," he counted on his fingers. "The first group, led by Zhang Hui, will thoroughly investigate Li Qiang's activities on September 10th, focusing on verifying his alibi from 8 PM to midnight, searching his residence and vehicle, and collecting DNA samples for comparison." He paused, then continued, "The second group, led by Yang Lin, will expand the on-site investigation to all residents of Building 3, focusing on the primary crime scene, especially the public areas and vacant houses near Unit 2, and conducting further physical evidence examinations on the wrench and chain."

“The third team will follow up with Wang Shuai, retrieve all surveillance footage from the area around the community, investigate those who had contact with Li Qiang on the evening of September 10, focus on finding the man wearing a serrated ring on his right hand, visit Zhang Guojun’s social connections, and verify the details of the dispute with Li Qiang.” Lu Chuan looked at Zhang Kai, “The technical department should speed up the DNA comparison process, especially the DNA from the skin tissue under the deceased’s fingernails and the cigarette butts at the scene. The results must be available today.”

As the morning light gradually filled the conference table, casting interplay of light and shadow on everyone's faces, Lu Chuan emptied the remaining tea from the enamel mug, the clanging sound startling everyone. "Pay special attention to whether Li Qiang's right hand has any injuries," he emphasized. "The skin tissue under Zhang Guojun's fingernails likely came from the suspect; this is crucial evidence. Also, investigate men in the community who wear blue polyester overalls, size 44 shoes, and smoke Yuxi cigarettes, especially property maintenance workers and construction workers."

When the meeting ended, Xiao Lin's notebook was filled with four full pages, each entry marked with a question mark and an exclamation mark. Yang Lin carried the crime scene photos towards the technical department, the motion-activated lights in the corridor turning on with his footsteps, illuminating the four gilded characters "Enforcing the Law for the People" on the wall. Zhang Kai took off his gloves, which were still stained with iodine, the smell of formaldehyde lingering on his fingertips. He remembered the black mole on Zhang Guojun's left scapula, hidden by clothing—this concealed feature had been confirmed during the autopsy, further solidifying the deceased's identity.

Li Qiang's summons had been filled out, and Lu Chuan signed his name in the issuing section. The sound of the pen gliding across the paper seemed to herald the impending confrontation. The water tank in Anju Community held too many secrets, and at this moment, sunlight pierced through the clouds, illuminating the path to the truth. Everyone knew that the next 24 hours were crucial; the DNA comparison results and the progress of Li Qiang's interrogation would determine whether this water tank body-dumping case could be successfully solved.

Yang Lin and Yang Sen's investigation records have been compiled. From shoe print characteristics to fiber composition, from lock marks to cigarette butt brands, every clue points to the murderer lurking in the shadows. Wang Shuai's surveillance investigation team is also ready to analyze the surveillance footage of the community and surrounding area frame by frame, leaving no suspicious figure unchecked. Zhang Hui, meanwhile, led his team straight to Li Qiang's building materials store, and a race against time officially began.

The conference room lights gradually dimmed, leaving only Zhang Guojun's photograph on the table. The wrinkles in his blue overalls were faintly visible in the shadows, as if silently recounting the events of that night, September 10th. The truth of the case lay hidden in these subtle clues and meticulous reasoning, waiting to be revealed one by one.

The incandescent light in the interrogation room of the Criminal Investigation Detachment was blinding. Li Qiang sat in the interrogation chair, his hands cuffed to the armrests; the clanging of metal was particularly clear in the quiet room. Zhang Hui pushed a glass of warm water in front of him. Water droplets from the glass dripped down the edge of the table onto the record book, spreading a small ink stain. "Tell me, what did you do to Zhang Guojun on the night of September 10th?" Zhang Hui's voice was calm but carried an undeniable force. His gaze fell on the silver ring with a serrated pattern on Li Qiang's right hand—it perfectly matched the characteristics of the finger pressure marks on the neck described by the forensic doctor. (End of Chapter)