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

After determining the cause of death, Zhang Kai began to estimate the time of death. "Xiao Lin, based on the body temperature and the state of rigor mortis and livor mortis, make a preliminary estimate of the time of death." Xiao Lin immediately took out a thermometer and measured the deceased's rectal temperature: "Rectal temperature 30℃, ambient temperature 22℃." Subsequently, she examined the deceased's rigor mortis and livor mortis: "Rigoletto has affected all major joints of the body, with moderate intensity. The jaw joint, shoulder joint, elbow joint, and hip joint cannot move easily; livor mortis is located on the back, buttocks, and back of the limbs, and is dark purplish-red in color. It does not fade completely when pressed. After changing the body's position, the original livor mortis does not disappear, and no new livor mortis appears at the pressure points."

Zhang Kai added, "Based on the pattern of body temperature decline, at an ambient temperature of 22℃, the body temperature drops by about 1℃ per hour after death. The deceased's rectal temperature was 30℃, which is 7℃ lower than the normal body temperature (37℃). It is preliminarily estimated that the time of death was about 7 hours ago. Combining the state of rigor mortis and livor mortis, rigor mortis affected the whole body and was of moderate intensity, while livor mortis did not fade completely upon pressure, which is consistent with the characteristics of body changes 6-12 hours after death. In addition, combined with the taxi receipts retrieved from the scene, the deceased last picked up passengers at 11:30 pm the previous night. Based on the comprehensive judgment, the time of death should be between 11:30 pm last night and 1 am this morning, that is, 5-7 hours before the incident."

"Teacher Zhang, are there any other methods to further pinpoint the time of death?" Xiao Lin asked. Zhang Kai said, "We can use the degree of digestion of the stomach contents to help determine the time. We'll cut open the deceased's stomach wall to see the state of digestion." He used a scalpel to cut open the deceased's stomach wall. There were a small amount of undigested food residue in the stomach, mainly rice, vegetables, and meat. The food was relatively intact and did not show obvious chymetabolism. "The food in the stomach is intact and has not chymetabolized, which indicates that it was digested 2-4 hours after eating. Assuming that the deceased last ate around 7 pm last night, then the time of death would be between 9 pm and 11 pm last night. However, this deviates from the time we estimated based on the body temperature, rigor mortis, and livor mortis."

Xiao Lin was puzzled: "What's going on? Could our deduction be wrong?" Zhang Kai shook his head: "The degree of digestion of stomach contents is affected by many factors, such as the type of food, the amount of food consumed, and individual digestive function. These can only be used as supplementary evidence. Based on the on-site investigation, the deceased last picked up passengers at 11:30 pm, and it is very likely that he was murdered while picking up the last passenger. Therefore, the time of death is more likely to be between 11:30 pm and 1 am. The deviation in the degree of digestion of stomach contents may be because the deceased ate less that night, or had better digestive function, resulting in faster food digestion."

Subsequently, Zhang Kai and Xiao Lin conducted a comprehensive examination of the deceased's abdominal organs: "The liver was of normal size, dark red in color, soft in texture, and without obvious rupture, bleeding, or nodules; the spleen was of normal size, of medium texture, and without enlargement or rupture; the kidneys were of normal size, with smooth surfaces, clear demarcation between the cortex and medulla, and no obvious abnormalities. There was no blood, fluid, or abnormal secretions in the abdominal cavity, ruling out the possibility of death caused by damage to the abdominal organs."

As the autopsy neared its end, Zhang Kai instructed Xiao Lin to organize the samples collected from the deceased's body: "We have collected a total of 12 biological samples, including hair samples, dust samples from under fingernails, neck muscle tissue samples, heart tissue samples, liver tissue samples, and stomach contents samples. All samples have been sealed and labeled and will be immediately sent to the technical department for DNA testing and toxicology analysis to see if any unexpected findings are found." Xiao Lin nodded, quickly organized the samples, and handed them to the technical department staff.

At 4:30 PM, the autopsy was completed. Zhang Kai and Xiao Lin organized the autopsy records and went to the Criminal Investigation Detachment's conference room to report the results to Lu Chuan. "Captain Lu, after a detailed autopsy, we determined that the cause of death for the deceased, Zhang Tiancheng, was strangulation. The estimated time of death is between 11:30 PM last night and 1:00 AM this morning, which highly matches the time on the taxi receipt retrieved from the scene. We speculate that the deceased was strangled to death by the suspect while picking up his last passenger," Zhang Kai said.

Lu Chuan quickly asked, "Did you find any clues pointing to the suspect during the autopsy? For example, the suspect's DNA, special fibers, or traces?" Zhang Kai shook his head helplessly: "Currently, we haven't found any major clues clearly pointing to the suspect. Although we extracted dust samples from under the victim's fingernails and hair samples from the body surface, preliminary observation revealed no traces belonging to the suspect; the ligature groove on the neck had clean edges, and no skin tissue or hair of the suspect was extracted; the biological samples extracted during the autopsy have been sent to the technical department for further testing, but there are no results yet. In addition, we determined through the autopsy that the murder weapon was likely a soft, strip-shaped object about 1.2-1.5 cm wide, but we cannot determine the specific type of object, nor can we identify the suspect based on the murder weapon."

Xiao Lin added, "We also extracted samples from the deceased's body for poisoning screening, ruling out the possibility of death by poisoning, but so far no other valuable clues have been found. In summary, although the autopsy examination determined the cause and time of death, providing direction for the investigation, it did not find any key clues pointing to the suspect. The case investigation still needs to rely on physical evidence collected from the scene and subsequent interviews and investigations."

After listening to the report, Lu Chuan frowned and fell into deep thought. Although the forensic autopsy had determined the cause and time of death, narrowing the scope of the investigation, no key clues about the suspect had been found, and the case still faced significant difficulties. "The technical department must speed up the testing of all physical evidence and autopsy samples, focusing on comparing the correlation between the unfamiliar fingerprints and cigarette butt DNA collected at the scene and the deceased's samples, and analyzing the composition of the white synthetic fibers; investigators must continue to follow the deceased Zhang Tiancheng's last operating route, retrieving surrounding surveillance footage and investigating the identity of the last passenger; at the same time, intensify the investigation of Zhang Tiancheng's social connections to look for possible clues of revenge killing or robbery." Lu Chuan issued the deployment instructions again.

Stepping out of the meeting room, Zhang Kai patted Xiao Lin on the shoulder: "Although this autopsy didn't uncover any direct clues about the suspect, we've determined the cause and time of death, which is the greatest support for the investigation. Next, we need to closely monitor the technical department's test results and be ready to provide forensic technical support for solving the case at any time." Xiao Lin nodded, his eyes filled with determination. The lights in the forensic identification center remained bright, like a lighthouse in the darkness, guiding the investigation into this taxi driver's murder. (End of Chapter)