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

“Look at this area of ​​bleeding, extending from the muscle belly to the tendon attachment point, covering an area of ​​4×5 centimeters. This is not something that could be caused by ordinary external force.” He asked Kobayashi to adjust the focus of the microscope. “The shape of the muscle fiber rupture is an acute-angle tear, which is consistent with the characteristics of continuous pressure applied when strangling. Moreover, the bleeding density on the left side is significantly higher than that on the right side, indicating that the murderer used more force with his left hand.”

The probe turned to the fracture site of the greater horn of the hyoid bone. The fractured bone was ivory white, with small fragments of periosteal tissue clinging to the edges. "The location of the hyoid bone fracture is crucial," Zhang Kai's voice deepened through his mask. "The fracture line at the junction of the greater horn and the body is oblique, accompanied by subperiosteal hemorrhage, which is typical of thumb pressure." He compared it to anatomical atlases. "This type of fracture occurs in about 68% of strangulation cases, especially in male victims weighing over 70 kilograms. It would require at least 30 kilograms of grip strength to form. Considering the thickness of the victim's neck muscles, the killer's strength must have been considerable."

The subconjunctival hemorrhages appeared as star-shaped spots under a magnifying glass, extending from the corneal margin to the inner eyelid. "These hemorrhages have a density of eight per square millimeter," Zhang Kai measured with a ruler, "and they extend to the fornix of the conjunctiva, a specific sign of death by asphyxiation." He asked Xiao Lin to take photos. "When the airway is blocked, the pressure inside the chest cavity rises sharply, causing small blood vessels in the conjunctiva to rupture. This diffuse hemorrhage is fundamentally different from the pinpoint hemorrhages of a heart attack—the latter do not appear in the fornix."

The results of the blood sample test had just been uploaded to the computer in the autopsy room. Zhang Kai scrolled through the data with the mouse: "Blood oxygen saturation 42%, carbon dioxide partial pressure 89 mmHg. These data are irrefutable evidence of mechanical asphyxiation." He pointed to the blood gas analysis chart, "Normal arterial blood oxygen saturation should be above 95%, but the deceased's value was less than half, accompanied by severe respiratory acidosis. This is a typical manifestation of hypoxia for more than 6 minutes, which perfectly matches the time window for strangulation."

Regarding the composition of the pig feed in the stomach, Zhang Kai used tweezers to pick up a whole corn kernel: "The morphology of these food residues is crucial," he said, placing it on a glass slide. "The corn kernel's seed coat was not broken, and the starch granules in the endosperm still maintained a complete layered structure, indicating very low chewing, more like it was forcibly fed in." He compared it with samples of pig feed from the farm: "The pig feed from the farm is pulverized, with particle diameters not exceeding 3 millimeters, while the corn kernels in the stomach have an average diameter of 5 millimeters, clearly indicating they are not the same type of food."

Xiaolin suddenly noticed something unusual in the chyme in the duodenum: "Teacher Zhang, there's a 2-centimeter-long piece of pig hair here, the follicle has fallen out." She examined it under a microscope and found "obvious mechanical damage on the hair shaft, as if it had been torn off by external force." Zhang Kai took the sample and shone it under an ultraviolet lamp. The surface of the pig hair showed a pale blue fluorescence: "This is a characteristic of being soaked in saliva, but it lacks friction marks from swallowing, further proving that it was inserted after death."

He instructed the technicians to extract tissue samples from the stomach wall: "To conduct a histopathological examination, focusing on the blood vessels in the submucosa." Preliminary sections showed that the bleeding points in the gastric mucosa were limited to the mucosal layer and did not involve the muscular layer. "This superficial bleeding was caused by foreign objects being injected during the dying period or after death, which is completely different from the mucosal tears caused by vomiting before death—the latter would have longitudinal mucosal damage and blood clots."

When the probe was inserted into the trachea again, Zhang Kai carefully observed the color of the mucous membrane: "Look here, the mucous membrane is pale white, without edema or inflammation," he wiped with a sterile cotton swab, "There's not even the most common cilia collapsing, which means the deceased had lost the ability to breathe when strangled and could not inhale any foreign objects." He compared the lung slices, "The number of macrophages in the alveolar cavities is normal, and no pig feed particles or bacteria have been engulfed, completely ruling out the possibility of suffocation caused by inhaling pig feed before death."

“So this pig feed could only have entered the body after death,” Zhang Kai arranged the slides in order. “Either the murderer deliberately poured it in to disguise the scene, or the hungry pigs naturally put it in when the body was thrown into the pigpen.” He pointed to the skin folds at the corner of the deceased’s mouth. “There were no bruises or scratches from food residue on the skin at the corner of the mouth, so it’s more likely to be the latter—if it was forced feeding, there would definitely be traces of external force at the corner of the mouth.”

Xiaolin suddenly noticed that the sphincter at the entrance of the esophagus was contracted: "Teacher Zhang, it's closed here!" She gently probed it with a probe, but the sphincter showed no signs of relaxation. "If the food was ingested before birth, the esophageal sphincter should be relaxed, especially 3-4 hours after ingestion, when the food has entered the stomach. The sphincter would return to normal tension, but it wouldn't be this tight." This discovery completely ruled out the possibility of ingesting pig feed before birth and also explained why the stomach contents did not reflux into the trachea.

Zhang Kai finally examined the deceased's temporalis muscle and found pinpoint hemorrhages deep within the muscle: "This is further evidence of death by asphyxiation," he said, cutting open the muscle with a scalpel. "When intracranial pressure increases, small blood vessels between the skull and the temporalis muscle rupture, forming this specific 'muscle hemorrhage,' a deep manifestation of Tardieu's spots in forensic pathology." He closed the autopsy record. "Considering the five major signs—hyoid bone fracture, neck muscle hemorrhage, subconjunctival hemorrhage, abnormal blood oxygenation, and muscle hemorrhage—the diagnosis of mechanical asphyxiation can be established 100%. As for the pig feed in the stomach, it was merely a smokescreen used by the murderer to confuse the victim."

As Xiaolin was recording the final autopsy data, she looked up and asked, "Professor Zhang, could the old injury on the deceased's left calf affect the estimation of the time of death?" She pointed to a healed fracture mark, "The X-ray shows an old tibial fracture that has healed, but it may affect blood circulation, which in turn affects the rate at which the body temperature drops."

Next is the short legs at the time of death.

Zhang Kai bent down to examine the X-ray of the deceased's left lower leg. A clear healing fold line was visible in the mid-section of the tibia on the screen, with the callus forming a spindle shape around the fracture, its density significantly higher than the surrounding bone. "This fracture has healed for at least eight months," he said, tracing an arc on the screen with his finger. "The callus has fully formed, the medullary cavity is open, and from the imaging, blood circulation should have almost fully recovered." He asked Xiao Lin to pull up the angiography images of the leg. "Look at the contrast of the anterior and posterior tibial arteries. Although there is slight tortuosity at the fracture site, the blood flow velocity is only 3 ml/min different from the healthy side. This difference has a negligible impact on overall circulation."

He picked up the rectal thermometer readings and laid out the formula for estimating the time of death on the autopsy table. (End of Chapter)