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

"The phone model is new this year, with Beidou positioning function, maybe it can find the last location." In the bottom compartment of the bag, a scenic spot ticket stub caught his attention. The date was three days ago. "The deceased stayed in the scenic spot for at least more than 72 hours."

Zhang Hui rushed over at this time: "Other hikers added that they had seen the deceased in a store at the entrance of the valley. The owner said that the man asked for directions to the no-man's land and bought a lot of compressed biscuits and waterproof cloth." He spread out the map of the scenic area and pointed at a certain coordinate. "The entrance to the no-man's land is 5 kilometers away from here in a straight line, but there is no formal trail and you have to go through the primeval forest."

As the sun sets, the on-site investigation is drawing to a close. Yang Sen puts the blood-stained hemp rope into the evidence bag: "Preliminary judgment is that the deceased was attacked near the bushes, dragged to the river and strangled to death. The murderer has some outdoor experience and used professional carabiners and ropes, but missed the fluorescent reaction of the river beach when cleaning the scene."

Lu Chuan drew a simple diagram on the whiteboard: "Zhang Hui led the team to check the scenic area surveillance, focusing on checking suspicious people who carried mountaineering equipment in the past three days; Yang Lin and Yang Sen conducted further detailed on-site inspections." He looked toward the valley, and the differential wind blew up the grass leaves on the river bank, as if the lingering smell of sin was still echoing.

The air was filled with suffocating heat. Yang Lin took off his sweat-stained helmet. His forehead was already bruised by the brim. He squatted on the gravel-covered riverbank, holding a magnifying glass and moving inch by inch. His eyes were bloodshot behind the lens, not missing any slight abnormality. Suddenly, a little metal reflection among the gravel caught his attention. He gently inserted the tweezers and took out a metal buckle with dark red rust. There were still a few dark brown hairs wrapped around the edge.

"Yang Sen, multispectral imager!" Yang Lin's voice echoed in the empty valley. Yang Sen quickly came over with the equipment on his back. His black exploration suit had long been soaked with sweat and stuck tightly to his back. The moment the instrument was turned on, a light blue beam swept across the rocks on the river bank, and a fresh scratch appeared under the purple light. The edges of the scratch were jagged and dotted with metal debris. "The carbon content is 0.45%, which is consistent with the material of the steel pipe weapon before." Yang Sen pointed the microscope at the debris, and the metal crystal structure in the eyepiece was clearly visible. "This should be left by the collision between the weapon and the rock."

The two searched in the direction of the scratches. In the bushes 20 meters away from where the body was found, a large area of ​​fallen weeds formed an obvious dragging track. Yang Sen took out the total station, and the red laser shuttled through the weeds, accurately measuring every angle: "The dragging angle is 17 degrees, and the direction of the grass blade break at the starting point is northwest, which means that the murderer dragged the deceased to the river from that direction." Yang Lin lay on the ground and carefully measured the footprints with a ruler: "42-size hiking boots, jagged patterns, stable strides; there is also a set of 40-size sports shoe prints, with blurred edges, messy strides and traces of backwards, and the interval between the two sets of footprints is no more than half an hour."

The roar of the drone's propellers broke the silence of the valley. Yang Sen controlled the device to slowly rise into the air, and the aerial camera captured the entire scene. On the tablet, the 50D modeling data was constantly updated, and the river beach, bushes, and dragging traces were accurately restored into a D map. "Look here." Yang Sen suddenly zoomed in on the picture. On the hillside meters away from the starting point of the dragging, the petals of several wild roses were scattered on the ground, and one of them was stained with dark red blood. "The murderer may have launched the first attack there."

The exploration team searched up the hillside. Next to a sunken stone pit, the luminol reagent sprayed by Yang Sen instantly emitted a faint blue fluorescence. "Sure enough!" He squatted down and carefully extracted the blood in the cracks of the stone with a cotton swab. "This place has been deliberately cleaned, but the trace amount of blood that has seeped into the cracks was missed." Not far away, Yang Lin's metal detector made a sharp beep. The probe penetrated into the soil, revealing a broken climbing rope. The hair wrapped around the knot was exactly the same as what was found before.

Back in the makeshift mobile laboratory, Janssen numbered the hundreds of samples he had collected. Under the microscope, the scale structure of the hair clearly showed that it belonged to humans; the display screen of the gas chromatograph kept jumping, and unfamiliar DNA was detected in the dandruff extracted from the carabiner; the soil analysis report pointed out that the red soil on the soles of the deceased's shoes only existed near the mine on the west side of the valley. These clues seemed clear, but like scattered puzzle pieces, they could never piece together a complete picture.

The visiting team led by Zhang Hui repeatedly checked the shops around the scenic spot and finally got a clue in an outdoor goods store: the day before the incident, someone bought the same climbing rope and waterproof cloth as the deceased. The owner checked the surveillance video and saw that the customer wearing a baseball cap kept his head down, with only the blue stubble on his chin showing. He used the old version of banknotes that had long been discontinued when paying. The team members followed this clue, but found that after the man walked into the pedestrian street, he disappeared into the dense crowd, like a stone sinking into the sea.

Lu Chuan stood in front of the whiteboard at the headquarters, looking at the dense clues and arrows on it, his brows knitted into the shape of a "Chuan" character. Yang Sen handed over the latest investigation report. In the drone footage, the black pickup truck that appeared at the entrance of the valley once again attracted everyone's attention. But when the police retrieved all the surrounding traffic surveillance and compared the vehicle features frame by frame, they found that the car suddenly changed its license plate after entering the highway entrance and completely lost its trace.

"The murderer is too familiar with this area." Yang Lin wiped the sweat from his forehead, his voice full of fatigue, "From choosing the crime scene, to cleaning up the scene, to avoiding surveillance, every step was carefully planned." Yang Sen nodded in agreement: "And he seems to know our investigative ideas and deliberately left these clues, but we can't grasp the key."

As night fell, exploration lights lit up in the valley. Yang Sen and Yang Lin were still investigating the site, their shadows elongated by the lights, swaying on the rock wall. Yang Sen turned on the multi-spectral imager again, and when the beam swept across an inconspicuous rock crevice, a faint fluorescence was looming. He held his breath and carefully dug with a probe, and a metal nameplate engraved with strange symbols broke out of the ground, glowing strangely in the moonlight.

In the evening, the body was transported to the Criminal Investigation Team.

The dusk cast a dark red hue on the Criminal Investigation Detachment Building. The cold air in the autopsy room contrasted sharply with the heat outside. Zhang Kai wore a protective mask, and the rubber gloves collided with the metal scalpel, making a crisp sound. The shadowless lamp illuminated Li's body palely. On the surrounding instrument tables, bone saws, tweezers and other tools glowed coldly. (End of this chapter)