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

Sunlight filtered through the ginkgo leaves of Anju Residential Area, casting dappled shadows on the ground. Zhou Qiang, the maintenance team leader of the property management company, slumped against the flowerbed in front of Building 3. The wrench in his hand clattered to the concrete, and his rusty fingers gripped his phone tightly, the screen still showing the dial-110 interface. "It was terrifying... I just opened the water tank and saw..." His voice trembled, and beads of sweat streamed down his forehead, staining his shirt collar with dark marks.

As soon as Lu Chuan's police car came to a stop, a cordon was quickly set up around the entrance of Building 3. As he approached the water tank using the investigation platform, a strong smell of rust and disinfectant hit him. The square water tank, embedded in the side of the building, was about 2 meters high. Its stainless steel casing gleamed coldly in the sunlight. The circular cover of the inspection port was lying to the side, with a broken chain still hanging from its edge. "Secure the scene and notify the technical department for backup," Lu Chuan's voice sounded muffled through his mask. His gaze fell on the faint red marks on the edge of the tank opening—like bloodstains from something scraping against it.

Yang Lin was using a laser rangefinder to measure the parameters of the water tank, the beam of his surveying light drawing a bright line on the tank. "The water tank has a volume of 5 cubic meters, an access port diameter of 60 centimeters, and is 1.8 meters above the ground," he said, crouching down to examine the outside of the tank. "There is slight rust on the bottom of the tank, but the overall structure is intact. The access port lock was forcibly broken, and the lock cylinder has obvious pry marks, which matches what Zhou Qiang said about 'broken chains'." He suddenly pointed to a scratch 1.2 meters above the ground on the tank, "There are fresh scratches here, going from bottom to top, like they were rubbed when moving heavy objects."

Wearing white gloves, Yang Sen was shining a footprint light on the ground. On the cement ground at the entrance of the building, a string of size 44 athletic shoe prints was particularly clear, with damp mud clinging to the edges of the prints. "The forefoot pressure is concentrated on the outer side, the stride length is 75 centimeters, and the stride width is 16 centimeters," he said, using a ruler to mark the edge of the prints. "The gait is steady, with a stride angle of 6 degrees outward, estimating a height of 178-183 centimeters. The prints extend from the entrance of the building to below the water tank, with a clear pause directly below the access panel. The tread pattern on the soles is inlaid with red soil from around the water tank."

Wang Shuai placed the interrogation record book on the desk in the property management office. Zhou Qiang's fingers repeatedly traced the date "9:15 AM, September 12th." "We clean the water tanks quarterly according to regulations," he said, his fingernails leaving shallow marks on the "maintenance record." "Today it was Building 3's turn. Xiao Li and I had just opened the lock and lifted the cover when we saw a person floating on the water…face down, wearing blue overalls. I was so scared my legs went weak." He suddenly shuddered. "The water in the tank is the entire community's drinking water; just thinking about it makes me shudder."

Yang Lin's inspection light swept across the inner wall of the water tank. A small amount of white foam floated on the surface, and the water appeared slightly turbid. "The water surface is about 80 centimeters from the access port," he measured with a telescopic ruler. "There are vertical scratch marks on the inner wall of the tank, extending from the water surface to the access port, as if someone tried to climb it." In the sediment at the bottom of the tank, there was an irregular protrusion partially covered by a transparent plastic bag, from which a human-shaped outline could be vaguely seen. Yang Sen found an anomaly at the drain pipe interface on the outside of the water tank: "There are fresh traces of tape wrapped around it, as if someone tampered with it, possibly to control the water level."

"Have any strangers been frequently entering and leaving the community lately?" Wang Shuai's pen traced an arc on the paper. Zhou Qiang suddenly slapped his thigh: "Yes! Starting last Wednesday, I've been seeing a man in a black jacket loitering around Building 3. When I ask him who he's looking for, he stammers and can't answer. He's also been smoking in the green belt next to the water tank." He gestured his height, "About your height, a bit hunched over, his left hand is always in his pocket, and his footsteps are very heavy." Property surveillance footage showed that the man had tried to approach the water tank at 3 pm on September 10 and was driven away by patrolling security guards.

Yang Sen discovered a crucial clue in the bushes of the green belt. A clump of roses had been trampled down, sap still seeping from broken branches, and there was a shallow pit in the ground, its shape matching the edge of a water tank lid. "Heavy objects were placed here," he said, collecting fibers from the edge of the pit with an evidence bag. "It's blue polyester, matching the color of the deceased's work clothes as described by Zhou Qiang." Deep within the bushes, a silver button was half-buried in the soil, with four round holes and worn patterns on its surface, matching the common style of work clothes buttons.

Yang Lin found a half-smoked cigarette butt in the grout between the floor tiles around the water tank. "Yuxi brand, 3 centimeters long, moderate smoking," he carefully removed it with tweezers. "The saliva stain on the filter is clear; I need to do a DNA test when I get back." There was a light red mark on the cement floor next to the cigarette butt, which tested positive after being wiped with an alcohol swab—suspected bloodstain. He suddenly noticed that the bolts on the water tank bracket were loose, and the wrench marks were fresh, as if someone had recently tampered with them.

Wang Shuai's inquiry turned to the security situation of the community. "Isn't there surveillance in the water tank area?" He pointed to the blank wall above the maintenance port. Zhou Qiang looked embarrassed: "There used to be surveillance, but it broke last month and hasn't been repaired yet. The property management said they are short of funds." He pulled up the surveillance records of the community entrance and exit. At 11:23 pm on September 11, a blurry black figure pushed a cart into the community. The cart was covered with a blue waterproof cloth. Its outline was similar in size to the water tank. It left empty at 2:17 am.

Yang Lin made a new discovery at the overflow pipe of the water tank. The pipe opening was blocked by a rag, the fabric fibers of which matched those found in the flower bushes, and the rust on the rag was identical to the metal components of the water tank's lock. "This was deliberately blocked," he analyzed, "to prevent the body from being washed out by the water flow after sinking, thus prolonging the discovery time." Yang Sen, on the other hand, found an anomaly in the access control records of the unit door: at 10:05 pm on September 11, the fire escape door of Building 3 was opened abnormally, and the system record showed that the electronic lock was forcibly damaged.

As technicians began setting up the exploration platform in preparation for the salvage operation, Lu Chuan's gaze fell on the fingerprints on the edge of the water tank's opening. "Besides the maintenance worker's fingerprints, there are also unfamiliar fingerprints," he said to the officer beside him. "Check the recent renovation workers and migrant workers in the community, focusing on men who are 178-183 cm tall, wear size 44 shoes, and smoke Yuxi cigarettes." The ginkgo leaves in the distance rustled in the wind, as if sighing for the secret hidden in the water tank.

As Wang Shuai closed the notebook, Zhou Qiang was still muttering about the floating corpse. "The face was pale from being submerged in water," the old man's voice trembled, "His right hand seemed to be gripping something, swaying back and forth in the water… Thinking about it now, that posture looked like a cry for help." Yang Sen suddenly noticed a black cloth bag behind the electrical box next to the water tank. The drawstring of the bag was stained with the same red soil as the one next to the cigarette butt. The wrench inside the bag was the same model as the one Zhou Qiang had dropped—but it didn't belong to the maintenance team. (End of Chapter)