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

Yang Lin and Yang Sen's investigation records have filled two pages. From the characteristics of the severed finger to the work boot prints, saw blades, and buttons, every clue points to people inside the factory. At this moment, the mystery of who the severed finger belonged to, why it appeared in the garbage room, and the suspect's motive remains unsolved. However, as the investigation deepens, the truth will eventually be exposed to the light of day, just like the severed finger that has been unearthed.

Afterwards, Lu Chuan arranged for two more people to expand the scope of the on-site investigation, including the entire factory area.

When Lu Chuan's instructions came through the walkie-talkie, Yang Lin was squatting beside a pile of scrap wood in the garbage room, using super glue to develop a potential fingerprint. "Expand the investigation area to the entire factory area, focusing on the woodworking workshop, paint shop, raw material warehouse, and the area around the factory perimeter wall. Be sure to collect trace evidence meticulously." Amidst the static and the roar of factory machines, Yang Lin put the fingerprint film he had just fixed into an evidence bag, looked up at the midday sun—sunlight streamed through the factory windows, casting dappled shadows on the ground, and the smell of sawdust and paint in the air was particularly strong.

“Received. Let’s start with the woodworking workshop.” Yang Sen followed, carrying his survey bag. The cable of the footprint lamp left shallow marks on the sawdust floor. He also held an electrostatic precipitator and magnetic powder in his hand. “We need to trace the size 43 work boot print in the garbage room. Maybe it can lead to the interior of the workshop.”

Inside the woodworking workshop, large saws and planers were neatly arranged, with fresh sawdust and wood waste scattered on the floor. Yang Lin took out black magnetic powder from his investigation bag and lightly sprayed it onto the control panel of a vertical saw. "There's a fragmented fingerprint here," he said, brushing it with a soft brush. The fingerprint pattern gradually appeared under the black powder. "It's a whorl pattern, the central design is unclear, and only 12 feature points remain. It needs to be sent to the lab for laser development." He used transparent tape to collect the fingerprint and attached it to a special card. "The extracted area is 2.1 × 1.8 cm, presumably left by an adult male index finger, with traces of sawdust contamination around the edges."

Yang Sen's footprint light swept across the workshop floor, and a size 43 work boot print clearly appeared on the sawdust layer, with a stride length of 75 centimeters, a stride width of 18 centimeters, and a 4-degree outward gait, perfectly matching the shoe print characteristics of the garbage room. "The pressure surface of the shoe print is concentrated on the outer side of the forefoot, and the pressure on the heel is even," he said, using a ruler to mark both ends of the shoe print. "The gait characteristics indicate that the suspect's center of gravity was biased to the right when walking, possibly indicating a minor injury to the right lower limb, or a habitual shift in the center of gravity." The shoe print turned around next to a horizontal planer and extended to a pile of waste materials in the corner of the workshop.

“Look at this pile of waste,” Yang Sen said, brushing aside the sawdust to reveal a wooden board stained with dark red. “The wood is pine, with fresh saw marks on the surface. The stains are dotted, 0.3-0.5 cm in diameter, consistent with the pattern of dripping blood.” He wiped it with an alcohol swab, which immediately turned dark red. “The preliminary test is positive, suspected to be blood. It needs to be sent to the laboratory for confirmatory testing and DNA typing.”

Yang Lin squatted beside the planer, his investigation light illuminating a scratch on the ground. "The scratch is about 30cm long and 5cm wide, and its direction is consistent with the shoe print," he measured the angle of the scratch with a protractor, "forming a 15-degree angle with the ground. There are wood fiber remnants at the edges, which may have been formed when dragging a heavy object—could it be left by the suspect dragging pieces of a corpse?" Yang Sen nodded, took out luminol reagent from his bag, and sprayed it on the scratch. A pale blue fluorescence instantly lit up, "Positive for occult blood, and the pattern is consistent with the stains on the wooden planks in the waste pile, so it is very likely from the same source."

The two followed the shoe prints and traces of blood toward the raw material warehouse, which was filled with logs and planks, and the air was thick with a damp, musty smell. Yang Sen's footprint light stopped in front of a pile of planks in the middle of the warehouse, where the size 43 shoe prints showed a clear pause and overlap. "The shoe prints overlapped three times," he noted, "which indicates that the suspect lingered here for a considerable period of time, possibly to hide items or dispose of body parts."

Yang Lin shone his survey light into the gap between the planks and discovered a 10cm-long section of human lower limb tissue between two pine planks. The skin was pale, the muscle tissue was partially decomposed, and there were irregular tear marks on the edges. "The body part is tissue from the middle section of the right lower leg," he carefully extracted with sterile tweezers. "The skin surface was covered with sawdust and white paint debris, which initially matched the paint composition found on the severed finger in the garbage room. The fracture surface had a serrated texture, which is presumed to have been caused by a sawing tool, and it matches the shape of the blade of the 18cm hand saw blade found earlier."

“This confirms our suspicions,” Yang Sen leaned closer to observe. “The suspect sawed the body in the woodworking workshop and then moved the pieces to different locations in the factory in batches. The severed finger in the garbage room was just one part of it.” He found a metal button next to the body parts, which was the same style as the button found in the garbage room. “It was round with four holes, made of metal, with the same wear pattern on the surface, and the buttonholes were wrapped with blue fibers, which were consistent with the fiber composition of the factory workers’ work clothes.”

When the investigation expanded to the paint shop, the smell of paint in the air became even more pungent. Yang Lin found half a clear palm print on the ground next to the paint mixing tank. "The palm print is from the outer part of the right palm," he explained, highlighting it with gray powder. "Twenty-one feature points were extracted; the lines are clear, there is no obvious contamination, and it can be directly entered into the fingerprint database for comparison." Next to the palm print, there was a light red wiping mark on the ground, about 20cm long. "The wiping direction was from the mixing tank towards the workshop entrance; the edges of the mark are blurred, suggesting it was left by the suspect when cleaning up bloodstains."

In the paint shop's waste bins, Yang Sen found a paintbrush stained with dark red ink, with several strands of dark hair tangled in its bristles. "The paintbrush is a 5cm wide flat-headed brush with nylon bristles," he observed the hair under a microscope. "The hair is 12cm long, black, coarse, with intact cuticles and hair follicle remnants at the root, allowing for DNA extraction and comparison with the body parts." He added, "The stains on the paintbrush tested positive in preliminary tests, and the paint composition is completely consistent with the white paint on the severed finger and body parts."

The two continued their investigation of the area surrounding the factory wall. At the base of the wall in the northwest corner, they discovered fresh climbing marks. "The wall is 2.2 meters high, and there are multiple footprints on the surface," Yang Sen measured the height of the marks. "The highest point of the footprints is 1.8 meters from the ground, consistent with the climbing characteristics of someone 175-180cm tall. Blue fibers are embedded in the brickwork, consistent with the fiber composition of work clothes." In the soil outside the wall, there was a size 43 work boot print, with a stride length of 78 centimeters and a stride width of 17 centimeters. "The shape of the shoe print is consistent with that inside the factory, but the stride length has increased by 3 centimeters, indicating that the suspect increased their walking speed after climbing, possibly indicating an attempt to escape the scene."

"Do you think the suspect is an employee of the factory or an outsider?" (End of Chapter)