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

Yang Sen added, "But crucial clues are still missing—no traces of the murder weapon were found, no biological evidence of the suspect was found, and the connection between the nail and the cigarette butt still needs physical evidence to support it."

Yang Lin suddenly pointed to the oil stain test results in the logbook: "Gas chromatography analysis of this oil stain shows the presence of C12-C20 alkanes, characteristic components of 92-octane gasoline, consistent with the composition of the plastic fragments near the fire, indicating that the suspect did indeed carry a gasoline can." He paused, "But the size 42 shoe print suddenly disappears at the ridge, surrounded by hard rock, with no continuation, which is illogical—unless the suspect changed vehicles here." Yang Lin immediately opened the electronic map: "Three hundred meters east of the ridge is a farm road, passable by agricultural tricycles; two hundred meters west is an abandoned mine shaft, where the vehicle might be hidden."

The two decided to split up; Yang Lin went to investigate the farm road, while Yang Sen went to the abandoned mine. Yang Lin found several parallel tire tracks in the rubble of the farm road, spaced 1.2 meters apart and 18 centimeters wide—typical tire treads from a farm tricycle. “The tire tracks are fresh within 72 hours,” he said, covering the treads with rubbing paper. “There are three 0.5-centimeter transverse cracks on the tread, consistent with the characteristics of the tire tracks towards the mine.” Yang Sen made a discovery in the dust at the mine entrance—a complete size 42 shoe print, the forefoot pressure distribution perfectly matching the previous weighted gait. Next to the shoe print was a size 39 women's leather shoe print, the metal plate at the heel gleaming in the sunlight.

“The woman’s shoe print has a stride length of 55 centimeters and a stride width of 8 centimeters,” Yang Sen said into the walkie-talkie. “It runs parallel to the size 42 shoe print, and the gait is coordinated, indicating that the two people were traveling together. This explains the weighted gait—they may have been carrying something together.” Yang Lin had already found half a piece of plastic rope in the haystack at the end of the farm road. The weaving pattern of the rope end matched the fibers found at the mine entrance: “This is a packing rope made of polypropylene. There are obvious stretch marks at the break, which should be due to excessive weight. The soil on it is consistent with the soil in the valley.”

When the two met up, the setting sun had already cast long shadows on the mountains. Yang Lin's investigation bag contained 23 physical evidence samples, and Yang Sen's footprint analysis report was covered with red markings. "To summarize," Yang Lin leaned against the old locust tree, rubbing his aching back, "there were at least two suspects, a man and a woman. The man wore size 42 sneakers, and the woman wore size 39 leather shoes. They carried gasoline and pine branches to the mountain hollow to set fire to the place. After committing the crime, they retreated along the mountainside, stopped at the ridge, and then left in a farm tricycle." Yang Sen added, "But key physical evidence is still missing—no trace of the murder weapon was found, the specific source of the accelerant was not determined, and the purpose of the iron nail and industrial salt is unclear. We cannot yet form a complete chain of evidence."

As the last rays of sunlight swept across the valley, Yang Lin gazed at the marks left by the charred corpse that had already been removed. Suddenly, he remembered something: "The soil pH in the burnt area is 6.8, while it's 7.5 at the mine entrance. This 0.7 difference might be due to residual combustion aids. We should do ion chromatography analysis when we get back; it might find more clues." Yang Sen had already packed up his investigation equipment when Lu Chuan's voice came through his walkie-talkie: "Major discovery! The DNA comparison results for the deceased are in." The two exchanged a glance. Although expanding the investigation area hadn't yielded any breakthrough clues, these fragmented traces, like scattered puzzle pieces, were already faintly revealing the outline of the case.

That evening, the body was transported back to the Criminal Investigation Detachment, where forensic doctor Zhang Gai began to perform an autopsy.

Inside the autopsy room, as the charred corpse transported from the Wolf Valley was wheeled in, the smell of formalin clashed violently with the acrid odor, creating a suffocating mixture. Wearing double-layered latex gloves, Zhang Kai's fingertips gripped the zipper of the body bag, and charred skin fragments fell like black snowflakes. "The deceased is male, completely charred, with approximately 60% loss on combustion," his voice muffled through his mask, the scalpel gleaming coldly on the tray. "Preliminary observation suggests an age between 30 and 40 years old, estimated height 170-175cm, and weight approximately 65kg."

Assistant Xiaolin's measuring tape moved across the corpse, data rapidly jumping across the notebook: "The body is 172cm long, curled up from head to toe, with obvious thermal coagulation shrinkage at the joints of the limbs, a typical characteristic of a burned corpse." Her pen paused on the words "charred dark blue clothing fragments," the fabric fibers having been carbonized by the high temperature, initially matching the pale blue fiber composition found at the scene. "There's a ring-shaped metal object remaining on the left wrist," Xiaolin suddenly pointed to the corpse's wrist, "It's a stainless steel watch, the crystal is shattered, and the hands are stopped at 11:05." Zhang Kai leaned closer to examine it; several unburnt fibers were still wrapped around the clasp of the watch chain: "Extract fiber samples, and at the same time check the inside of the watch for any biological evidence."

The post-mortem examination revealed that the deceased's skin was charred all over, with multiple "glove-like" changes—a result of the skin separating from the subcutaneous tissue due to high temperatures. "Notice the irregular skin defect on the left side of the chest," Zhang Kai gently parted the charred tissue with a probe. "It's about 5 x 6 cm in size, with curled edges. We need to determine whether it's from pre-mortem trauma or skin rupture caused by burning." Xiao Lin sprayed alcohol on the defect, attempting to clean away the surface charcoal: "Professor Zhang, the tissue here is too brittle; it'll crumble at the slightest touch."

“Measure the body temperature first.” Zhang Kai didn’t reply, but inserted the electronic thermometer deep into the rectum. The number fluctuated around 22°C. “Ambient temperature 18°C, core body temperature 22°C,” he said, comparing the temperature change curve of the cremated body with his pen, tracing lines on the calculation paper. “High-temperature cremation will interfere with the estimation of body temperature, but rectal temperature is relatively less affected by external factors. At the normal rate of body cooling, it drops by 0.8-1°C per hour, but cremation will accelerate this process by 30%. The preliminary estimate of the time of death is between 12 and 24 hours, but it needs to be corrected for by other indicators.”

When cutting into the chest and abdominal cavities, the scalpel encountered significant resistance—the ribs had become brittle due to the high temperature, breaking into fragments with the slightest touch. "There are multiple fractures in the sternum and ribs," Zhang Kai carefully separated them with bone forceps, "but the fracture surfaces are honeycomb-like, indicating heat-induced fractures, not mechanical trauma." The organs inside the chest cavity were severely charred; the lungs were dark brown, hard as charcoal, and lacked normal tissue elasticity when cut. "Take lung tissue samples," Zhang Kai told Xiao Lin, "focusing on checking for soot and charcoal deposits; this is crucial for determining whether the person was burned alive or cremated after death."

As the scalpel sliced ​​open the trachea, a cloud of black ash suddenly gushed out. "Teacher Zhang, there's a lot of ash and charcoal dust on the tracheal wall!" Xiaolin's voice was filled with excitement as she carefully collected the sample with a pipette. (End of Chapter)