The crackdown on organized crime began with the arrest of the mother-in-law.

Chapter 1116 Expanding the Scope: Detailed On-Site Investigation Reveals...

As the last rays of sunlight pierced the bedroom curtains, Xiao Yang's investigation notebook was already filled with 28 clues. An untouched lock, the low temperature of the air conditioner, stains resembling blood, fibers from a red dress, the mysteriously missing cabinet… each clue was like a piece of a puzzle, waiting to be pieced together to reveal the complete truth. As Xiao Wang closed his notebook, Lao Li was still muttering about Zhang Lei's various unusual behaviors, while the stench in the hallway seemed to intensify, silently recounting the tragedy that had unfolded in this room.

Li Ming's rubber boots made a soft thud in the puddles in the entryway. He pointed to the air conditioner control panel on the wall: "A 24°C low temperature environment will affect the preservation of traces," his fingertip lingering on the words "cooling mode." "Expand the investigation scope to the entire building, check the stairwells, the rooftop, and the flower beds downstairs, especially the drainage pipes." He handed the evidence bag to Xiao Yang; the red fibers inside gleamed eerily in the sunlight. "Focus on comparing the warp and weft density of this polyester fiber; don't miss any corner."

Xiao Yang was squatting on the living room floor, adjusting a magnetic powder brush. Black magnetic powder formed a uniform film on the polyester fiber cloth. "Xiao Sun, look at these shoe prints," he said, measuring the stride length as 68 centimeters and the stride width as 12 centimeters with a ruler. "The pressure distribution on the forefoot is triangular, and the heel wear level is 3, which matches male characteristics. However, the edges of the shoe prints are blurry, indicating they were left on a damp surface—which matches the humidity of the water accumulation in the entryway." He asked the technician to place a ruler next to the shoe prints for a photograph. "Use side lighting to enhance the three-dimensionality, and be careful to preserve the details of the serrated pattern on the sole."

Xiao Sun carried a multi-band light source into the bedroom. The beam swept across the inside of the wardrobe wall; under 380nm ultraviolet light, a 50x30 cm area emitted a pale blue fluorescence. "There's a bloodstain reaction here," he said, measuring with an excitation light intensity meter, which showed a value of 2300mW/cm². "This is 40% higher than the residue on the living room carpet, indicating a larger original amount of bleeding." He used a sterile cotton swab to collect a trace amount of residue. "The ABO blood type is A, but DNA typing requires STR testing in the lab; currently, it's impossible to determine if it's from the deceased."

“The lock on the bay window in the master bedroom shows signs of being pried open,” Xiao Yang said, his probe wedged into the lock cylinder. “The pins are misaligned by 5 degrees, and there’s brass powder at the base of the latch. The thickness of the oxide layer indicates it’s fresh from three days ago.” He asked Xiao Sun to examine the powder with a scanning electron microscope. “It contains 12% zinc, which is standard for brass lock cylinders, but the tool used to pry it open was likely a flathead screwdriver with a blade about 8 millimeters wide.” On the air conditioner unit outside the window, Xiao Sun found half a blurry fingerprint. “After developing it with 502 glue, the center of the ridge is loop-shaped, but the details are insufficient; only 6 feature points can be extracted.”

Expanding the search area to the stairwell, Xiao Yang's magnetic brush made a discovery on the fire hydrant box outside apartment 302. "There's a complete sweat fingerprint here," he carefully extracted it with transparent tape, "The central pattern is whorl-shaped, with 10 clear feature points, and the ridge spacing is 0.23 millimeters. It has a 90% correlation with the brass powder composition on the bedroom window lock." The resident of apartment 302 is a retired teacher who confirmed that she did see someone loitering outside Zhang Lei's door last Saturday, "wearing a black jacket and a baseball cap, about 175 centimeters tall, and walking with a slight pigeon-toed gait."

Xiao Sun used a Raman spectrometer to detect the characteristic peak of red fibers in the bushes of the flower bed downstairs. "Wavenumber 1640 cm⁻¹, which is a typical absorption peak for polyester fibers," he said, comparing it with the database. "It matches the warp and weft density of the red fibers found in the bedroom, both being 150x100 threads/inch, but the degree of degradation is higher, so it should have been left over from about a week ago." In the soil deep in the flower bed, he extracted a size 42 serrated shoe print, with a stride length of 72 cm and a stride width of 10 cm, estimating a height of 175±2 cm, which matches the outward-pointing toeing characteristic described by the retired teacher.

“The black plastic bag in the trash can,” Xiao Yang said, picking up a torn piece of the bag with tweezers, “has fingerprints that match perfectly with those on the fire hydrant box.” He had the technicians take photos for their records. “The food scraps inside the bag contain Sichuan-style seasoning that matches the deceased’s stomach contents, but DNA typing shows it belongs to another man, possibly left by the person who disposed of the trash.” Several dark brown cotton fibers were wrapped around the rust on the edge of the trash can; infrared spectroscopy analysis showed they matched the material of common work pants.

The water tank lid on the rooftop caught Xiao Sun's attention; the dust around the edge showed signs of being disturbed. "The footprints we extracted match the shoe prints on the flowerbed downstairs," he said, using a laser rangefinder to measure the straight-line distance from the water tank to Zhang Lei's bedroom window. "It's 18.5 meters, a 3-meter height difference; it's entirely possible to climb in with a rope." However, water quality tests inside the tank showed no abnormal biological components, ruling out the possibility of hiding a body or murder weapon. "It just means someone went up there; it doesn't necessarily mean they're related to the case."

Xiao Yang noticed something unusual under the security camera in the hallway; the dust cover on the lens showed signs of being rotated. "The angle shifted by 15 degrees, just avoiding the area near the entrance to room 301," he said, reviewing the footage. "At 2:17 AM on July 4th, a figure wearing a baseball cap lingered in front of the camera for two minutes, after which a blind spot appeared in the view." Technicians disassembled the camera and found the memory card had been removed. "The metal contacts in the card slot were worn, indicating it had been forcibly pulled out; the fingerprints matched those on the fire hydrant box."

“All the fingerprints and footprints found so far can only be linked to an unknown male,” Xiao Sun said as he summarized the investigation data, the afterglow of the setting sun shining through the corridor window onto the investigation notebook. “But there is no direct evidence that he had any contact with the deceased. The red fibers and brass powder only indicate that he was present in the vicinity of the scene, but cannot establish a connection to the crime.” Xiao Yang added, “The Type A bloodstains in the bedroom, the pry marks on the window lock, and the deliberate damage to the surveillance cameras are all suspicious clues, but they lack specificity. For example, the complete whorl-shaped fingerprint has no matching record in the criminal record database.”

Back in the lab, on Xiao Yang's computer screen, all the clues formed a complex network. The fingerprints of the unknown man, red fibers, and jagged shoe prints formed one line; the victim's movements, debt disputes, and the mysterious female visitor formed another. The two lines intersected on July 3rd, but lacked a crucial connection point. "The most troublesome thing is that missing low cabinet," Xiao Yang said, zooming in on the 7D model of the scene. "Based on the scratches on the floor, it weighed about 80 kilograms and had dimensions of 120x60x50 centimeters. It would have required at least two people to move it, which suggests the killer may have had accomplices."

Xiao Sun's Raman spectrometer was still analyzing the last batch of fiber samples, and the fluctuating peak curves on the screen perfectly matched the material of a common red dress.