The crackdown on organized crime began with the arrest of the mother-in-law.

Chapter 1484 Determining the Time of Death

"The next key step is to determine the time of death. We will combine various factors, including post-mortem findings, the degree of digestion of stomach contents, and environmental factors, to ensure accurate results." Zhang Lin put down his scalpel and began to carefully observe the post-mortem findings. "First, we will observe the body's cooling. The rectal temperature is 30.2°C, and the ambient temperature in the autopsy room is 22°C. Based on the pattern of post-mortem cooling, combined with the body shape and ambient temperature, we initially estimate the time of death to be between 12 and 18 hours ago. However, since the body has been immersed in the river for a long time, the water temperature is low, which will slow down the cooling process. Therefore, we need to revise the estimated results."

Xiao Lin took out a thermometer and recorded the temperature in the autopsy room and the rectal temperature of the corpse. He added, "The river water temperature at the scene was measured at 18°C. The corpse was immersed in the water for about 8 hours. Based on the influence coefficient of water temperature on rigor mortis, the corrected rigor mortis estimate for the time of death is 15-20 hours." Zhang Lin nodded in agreement and continued, "Combined with the rigor mortis, the corpse's muscles showed moderate rigor mortis, mainly distributed in the jaw, neck, limbs, and torso. The intensity of rigor mortis was moderate, and the fingers and toes could move slightly, which is consistent with the characteristics of rigor mortis 12-18 hours after death. Since the aquatic environment delays the onset of rigor mortis, it basically matches the corrected rigor mortis result."

He pressed his fingers against the corpse's skin, observing the changes in skin color: "The livor mortis is mainly distributed on the back, buttocks, and posterior limbs, appearing as a dark purplish-red color. It does not fade when pressed, and the borders of the livor mortis are clear, indicating that it has entered the diffusion stage, consistent with the characteristics of livor mortis 10-16 hours after death. At the same time, the corpse's cornea is slightly cloudy, and the pupil is dilated, about 5 millimeters in diameter, with no light reflex. Combined with the degree of corneal opacity, this further confirms that the time of death is between 15-20 hours." Zhang Lin summarized the various post-mortem phenomena, saying, "Currently, based on the four post-mortem phenomena of coldness, rigor mortis, livor mortis, and corneal opacity, the corrected time of death range is 15-18 hours. Combining this with the degree of digestion of the stomach contents, and the fact that the last meal was 4-6 hours before death, the time of death can be further narrowed down."

To ensure the accuracy of the time of death determination, Zhang Lin decided to use histological examination to assist in the assessment: "Xiao Lin, take a small piece each of liver tissue, kidney tissue, and myocardial tissue, prepare pathological sections, and send them to the laboratory for histological examination. By examining the degree of cell degeneration and necrosis, we can further accurately estimate the time of death. In addition, extract cerebrospinal fluid and blood samples for biochemical testing to rule out the possibility of sudden death due to illness. At the same time, changes in biochemical indicators will help verify the time of death." Xiao Lin immediately collected tissue and body fluid samples as required, labeled them, and sent them to the laboratory.

While awaiting the results of the laboratory histological examination, Zhang Lin continued to perform a cranial anatomical examination and other examinations on the body: "The cranial anatomical examination was normal, there were no fractures in the skull, the dura mater and pia mater were smooth, there was no hemorrhage or edema in the brain tissue, the brain parenchyma was normal in texture, and there were no signs of lesions. There were no strangulation marks, ligature grooves, or other injuries on the neck, and no fracture of the hyoid bone, ruling out the possibility of death by mechanical asphyxiation. There were no dislocations in the joints of the limbs, no fractures in the bones, only minor abrasions and contusions, and no other fatal injuries."

"Teacher Zhang, should we compare the metal buttons and earrings retrieved from the scene with the body's clothing and skin?" Xiao Lin asked. Zhang Lin nodded: "Of course. We'll compare the metal buttons with the buttons on the deceased's coat to confirm if they come from the same type of clothing. The earrings can't be directly linked to the deceased yet, but based on the scene investigation, they were likely left by a female perpetrator. We'll analyze them later using DNA typing on the earrings. Also, we'll examine the seams of the deceased's clothing and compare them with the seam residue on the back of the metal buttons to see if there's a match."

Xiao Lin retrieved the metal button recovered from the scene and carefully compared it with the button on the deceased's coat: "The deceased's coat button is made of black resin and has a simple design. It does not match the material, style, or size of the metal button, ruling out the possibility that they came from the same garment. The stitching residue on the back of the metal button is made of cotton thread, which does not match the synthetic fiber stitching of the deceased's coat, indicating that the metal button came from the clothing of the perpetrator or other related individuals." Zhang Lin added, "Combined with the test results showing that the metal button was a button used on a niche brand coat ten years ago, the scope of the investigation of the perpetrator's clothing has been further narrowed, providing a direction for subsequent suspect identification."

At 11 p.m., the laboratory delivered the histological and biochemical test results. Holding the report, Zhang Lin carefully analyzed it and said, "The liver, kidney, and myocardial tissues showed mild degeneration, pyknosis of the cell nuclei, and increased eosinophilicity of the cytoplasm, consistent with histological changes 16-17 hours after death. The cerebrospinal fluid and blood biochemical indicators showed that blood glucose, potassium, and sodium levels were within the normal range, with no abnormal fluctuations, ruling out the possibility of sudden death from illness. The changes in biochemical indicators also correspond to the approximately 16-hour time of death."

Based on all the evidence, Zhang Lin finally determined the time of death: "Considering the post-mortem phenomena such as coldness, rigor mortis, livor mortis, and corneal opacity, the degree of digestion of the stomach contents, histological examination and biochemical test results, and taking into account the environmental influence of the body being immersed in the river, the final determination is that the deceased died between 2 and 3 a.m. on the day of the incident, and the last meal was between 10 and 11 p.m. the night before the incident." Xiao Lin quickly recorded this and, after confirming its accuracy, said, "Professor Zhang, the cause and time of death have been determined, and all samples collected during the autopsy have been sent to the laboratory for further testing and comparison."

Zhang Lin nodded and began organizing the autopsy instruments and cleaning the autopsy table. He then reviewed the entire autopsy process: "The autopsy results are highly consistent with the on-site investigation conclusions. The fatal injury was a stab wound to the chest with a single-edged sharp weapon, causing a ruptured heart and death from hemorrhagic shock. The characteristics of the weapon used in the crime are clear, the time of death is precisely determined, and the external injuries confirm the drag marks at the scene. However, two key doubts remain: First, the deceased's identity is unknown, with no obvious markings on the body and no identification documents. Further investigation using DNA databases and missing persons information is needed. Second, the specific identities and motives of the perpetrators are still unclear. Although trace evidence has led to the identification of a male and female perpetrator, there is a lack of direct, identifiable clues."

At midnight, the autopsy was completed. Zhang Lin began writing the autopsy report, meticulously recording the dissection process, test results, cause of death, and the basis for determining the time of death. He also attached supporting materials such as autopsy photographs and sample test reports to ensure the report was scientific, rigorous, and accurate. Xiao Lin was responsible for organizing the various samples and trace evidence collected during the autopsy and coordinating with the laboratory for subsequent testing to ensure that all evidence was properly processed and analyzed.