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

When the test results showed that the carbon-14 content corresponded to the time of death in the past five years, he finally wrote the conclusion in the report: "Combining the pubic symphysis, bone microstructure, tooth characteristics and carbon-14 dating, the age of the deceased is estimated to be 38-40 years old."

The process of confirming the cause of death was full of collisions between technology and logic. Zhang Kai cut open the skin along the rope groove on the deceased's neck. The subcutaneous tissue showed typical flake bleeding, and blood beads oozed from the broken muscle fibers in the front of the neck. "The greater horn of the hyoid bone is fractured, and the superior angle of the thyroid cartilage is fractured." He held up the broken bone and carefully observed the fracture surface under the shadowless lamp. "The fracture line is oblique and the edge is sharp, which is consistent with the shear force characteristics generated by the rapid tightening of the rope." After opening the chest cavity, the lungs showed a dark purple congestion state. When the lung tissue was cut, dark red bloody foam oozed from the cut surface.

"Subendocardial punctate hemorrhage is a hallmark pathological change of death by asphyxiation." Zhang Kai picked up the heart with tweezers and carefully examined the coronary arteries, "ruling out the possibility of death from heart disease." The most crucial evidence came from the trachea - he cut the trachea longitudinally with scissors and found several tiny hemp rope fibers two centimeters below the cricoid cartilage, which glowed grayish white under the dissecting light. "It's exactly the same material as the rope extracted from the scene." He put the fibers into the evidence bag and specially marked the sampling location when sealing it.

However, the pinhole behind the right ear became a new mystery. Zhang Kai sliced ​​the tissue around the pinhole and observed obvious inflammatory cell infiltration under the microscope, indicating that the injection occurred before death. The test results of the gas chromatography-mass spectrometry were shocking: the concentration of ketamine in the blood reached 0.8mg/L, which is enough to quickly put an adult into a coma. "First, he was anesthetized by drugs, then strangled after losing the ability to resist, and finally thrown into a dry well." Zhang Kai drew a timeline in the report, and the scalpel knocked on the table unconsciously, making a regular sound.

As the autopsy was coming to an end, Zhang Kai squatted down and carefully examined the soles of the deceased's feet. The wear marks showed a unique pattern: the inner side of the forefoot was deeply worn, the outer side was relatively intact, and there was a clear indentation on the arch of the foot. "This wear pattern," he said to the recorder, "usually appears in occupations that require long-term standing and frequent left and right turning movements, such as supermarket stockers, factory assembly line workers, or..." His voice suddenly paused, and his eyes swept over the lottery ticket in the pocket of the deceased's overalls - the scratch area on the back of the lottery ticket was stained with fine cement particles, which was exactly the same as the composition of the sample extracted at the scene.

The clock in the autopsy room pointed to six in the morning. Zhang Kai took off his blood-stained gloves and rubbed his temples tiredly. The three-hour autopsy process and hundreds of test data were finally condensed into a twenty-page report. Every measurement value accurate to one decimal place and every labeled microscope photo were the last testimony left by the deceased in the world. When he pushed open the door of the autopsy room, the morning light pierced through the clouds and sprinkled down. The city in the distance gradually woke up, and the puzzle of the truth about this nameless corpse was gradually being completed.

Zhang Kai sent the autopsy report overnight.

Early the next morning, Lu Chuan organized the first case analysis meeting.

In the meeting room of the Criminal Investigation Brigade, the incandescent lamps illuminated the walls palely, and the projector projected photos of the dry well scene in front of everyone. Lu Chuan stood in front of the whiteboard, holding a red pen in his hand, and his eyes swept over each team member present: "Today's case analysis meeting will focus on the on-site investigation and autopsy results to clarify the next step of the investigation. Yang Lin, you report the on-site situation first."

Yang Lin opened the investigation report in his hand and cleared his throat. "The dry well is located in the demolition area of ​​the old city. The diameter of the well mouth is 80 centimeters and the depth is 7.2 meters. We found splattered blood at the bottom of the well. The luminol test confirmed that it was human blood. By measuring the parabola angle of the blood drop, we preliminarily determined that this was not the first crime scene. The lead content of the soil on the well wall was detected to be 3 times higher than the standard, which is similar to the soil composition of the nearby battery factory that has been demolished, but no direct connection with the case has been found so far." He switched the projector screen to show the enlarged photos of the scene. "Cement debris was extracted from the clothes of the deceased. After testing, it was found that the composition of PO 42.5 cement was highly consistent with the construction site under construction in the west of the city. We have contacted the construction site to cooperate with the investigation, but the video footage of the key time period of the construction site monitoring was deleted, and no effective clues can be obtained for the time being."

"Are there any other findings on the deceased's clothes?" Zhang Hui asked, looking up.

Yang Lin shook his head: "After the clothes were vacuum-coated, no valid fingerprints or palm prints were extracted. There was only half a crumpled lottery ticket in the pocket. There were cement stains on the back of the lottery ticket, which was consistent with the cement composition of the soles of the deceased's shoes. In addition, the deceased did not carry any documents or items that could prove his identity."

"Now Zhang Kai will report the autopsy results." Lu Chuan looked at the forensic doctor sitting in the corner.

Zhang Kai stood up and walked to the projector. An autopsy photo of the deceased appeared on the screen. "The deceased is a male, 172 cm tall and 68 kg in weight. His age was determined by various methods and is estimated to be between 38 and 40 years old. The cause of death was mechanical asphyxiation. The neck cord groove was obvious, the greater angle of the hyoid bone was fractured, and hemp rope fibers were extracted from the trachea, which are the same as the rope wrapped around the neck of the deceased." He called up the image under the microscope. "There is a pinhole behind the right ear of the deceased. Ketamine was detected in the blood, and the concentration is enough to cause a coma. It is speculated that he was anesthetized by drugs first, and then strangled to death after losing the ability to resist."

"Have you found any characteristics that can point to the identity of the deceased?" Wang Shuai asked with a frown.

"The deceased had an old fracture in his right ulna, which took about 3-5 years to heal. In addition, he had caries on the left second molar in his mandible, and had undergone root canal treatment on the right first molar in his maxilla." Zhang Kai turned to the next page of the report, "We can use these two features to check the treatment records of dental clinics across the city. In addition, there are special signs of wear on the soles of the deceased's feet. The inner side of the forefoot is severely worn, while the outer side is relatively intact. This wear pattern usually occurs in occupations that require long-term standing and frequent turning, such as supermarket stockers and factory workers. This may provide a direction for investigating the deceased's occupation."

The conference room fell into a brief silence as everyone digested this information. Lu Chuan broke the silence: "Everyone, please express your opinions. How should we proceed?"

Wang Shuai spoke first: "The most urgent task is to identify the deceased. We should start with dental records and occupational characteristics. I suggest that we divide into two groups. One group will visit dental clinics throughout the city to find records of people who meet the characteristics of dental treatment. The other group will check possible workplaces based on the wear characteristics of the soles of the deceased's shoes, such as the construction site in the west of the city. Since cement debris from there was found on the deceased's clothes, we may be able to find someone who knew the deceased." (End of this chapter)