flstandardbreds Chapter 1118 Determining the Time of Death
Chapter 1118 Determining the Time of Death
He pressed the area with the densest lividity with his fingertips, and the color faded in about 2 seconds. "The fading speed was 1.5 times slower than at room temperature, which further verified the effect of low temperature."
Zhang Lin instructed Xiao Lin to collect liver tissue samples for histopathological examination. "The degree of autolysis in hepatocytes is an important indicator of time of death," he explained. "After death, hepatocytes gradually swell and undergo nuclear dissolution. Significant nuclear dissolution only appears after 36 hours at 24°C. In our sample, the degree of nuclear dissolution was only 30%, which fits this time window." Pointing to a section of hepatocytes under the microscope, he said, "Look at these cells; most still retain their intact shape, with only a few showing loose cytoplasm. This is evidence that low temperature delays autolysis."
The results of the muscle fiber rupture test were in. Zhang Lin looked at the values on the report: "The muscle fiber rupture rate is 25%. At 24°C, this value corresponds to a time of death of about 40 hours." He drew a cross-validation graph of multiple parameters on the autopsy record: body temperature, rigor mortis, livor mortis, corneal opacity, vitreous humor potassium ion concentration, degree of hepatocyte autolysis, and muscle fiber rupture rate. The seven curves finally converged in the interval from 8 pm on July 3 to 2 am on July 4, forming a dense cross-region.
“In addition, the degree of digestion of the stomach contents can also help in the judgment,” Zhang Lin observed the stomach contents sample again. “The starch granule destruction rate of the rice grains is 40%, and the muscle fiber breakage rate of the beef granules is 35%. According to our database, at a body temperature of 24°C, this degree of digestion would take 3-4 hours. However, if the ambient temperature is low, the activity of digestive enzymes will decrease, and the digestion time will be prolonged. But the deceased died after eating, and the temperature in the stomach was still close to body temperature, so the degree of digestion was not affected by the low external temperature. This closely links the time of death to the time of the takeout on the evening of July 3.”
Xiaolin organized the data, inputting all the parameters into the time of death estimation model. The results that popped up on the computer screen showed: "July 3, 20:00 - July 4, 02:00, confidence level 95%." She exclaimed, "So many indicators point to this time period, it's so accurate!" Zhang Lin nodded, the scalpel moving through the intercostal spaces of the corpse, preparing to open the chest cavity: "This is the significance of comprehensive judgment. A single indicator may be biased by environmental influences, but cross-validation of multiple indicators can yield the time window of death closest to the truth. Next, we'll do a histopathological examination to check the degree of muscle fiber rupture, further confirming this time window and making the conclusion more solid."
As the ribs were cut open by the chainsaw, the ear-piercing sound echoed in the dissection room. Zhang Lin's eyes were focused and determined, and every operation was precise and flawless.
When the chest cavity was opened, the putrefied lung tissue was grayish-red, like a bloated sponge. Zhang Lin used scissors to separate the bronchi, and mucus was drawn into thin strands on the blades. "The lungs weigh 1600 grams, 300 grams heavier than normal," he pointed to the bleeding points under the pleura, "They are pinpoint-sized, distributed along the edges of the lung lobes, consistent with death by asphyxiation, but we need to rule out mechanical asphyxiation or hemorrhagic shock." Xiao Lin suddenly found a 1cm laceration in the lower lobe of the right lung, with blood clots at the edges: "This injury is deep into the lung parenchyma, probably caused by a rib fracture, and there is a grating sensation in the corresponding chest wall."
The X-ray of the ribs lit up on the viewing light, showing a linear fracture of the 5th and 6th ribs on the right side of the chest, with the broken ends protruding into the pleural cavity. "The direction of the fracture line is on the same straight line as the hematoma in the right temporal region," Zhang Lin compared with a ruler, "indicating that it was a chain reaction injury caused by the same blunt force trauma, with the direction of the impact from the upper right to the lower left, and the force at least 80 joules, enough to cause internal organ rupture." He opened the pericardium, and dark red blood gushed out, "There was about 200ml of blood in the pericardial cavity, contusions on the surface of the heart, and fan-shaped hemorrhages on the left ventricular wall, which are typical manifestations of cardiac concussion injury."
The extraction of stomach contents was carried out with the hum of a negative pressure suction device, and pale brown chyme mixed with acid gushed out. "About 500 ml, containing undigested rice, beef bits, and chili seeds," Zhang Lin observed the sample under a microscope. "The muscle fiber striations of the beef bits are still clearly visible, indicating death 3-4 hours after ingestion, which matches the time of the takeout order on the evening of July 3rd." Xiao Lin suddenly pointed to the gastric mucosa: "There's a 0.3 cm erosion here, could it be caused by poison?" Zhang Lin shook his head, and with a scalpel, he cut open the entire thickness of the stomach wall: "There's no inflammatory cell infiltration around the erosion; it's caused by gastric acid corrosion, ruling out poisoning."
The corpse had extensive abrasions and contusions on its back. When Zhang Lin turned the body over, putrefactive fluid pooled in a thin stream in the groove of the autopsy table. "The contusions are distributed in patches, covering an area of about 15x20cm," he measured the boundaries of the contusions. "The vital signs have been disrupted by putrefaction, but the bleeding bands in the deep muscles are still clearly visible, consistent with the characteristics of being dragged before death, and the length is consistent with the drag marks from the living room to the doorway." He had Xiao Lin take a sample from the center of the contusions. "The myoglobin concentration is 180ng/mL, higher than the normal postmortem level, proving that it was an injury sustained before death."
“Teacher Zhang, look at the deceased’s fingernails,” Xiao Lin suddenly lifted the corpse’s wrist, the fibers under the fingernails glowing red under the operating light. “Raman spectroscopy analysis shows they are polyester fibers, with a warp and weft density of 150x100 threads/inch, which is exactly the same as the red fibers found at the scene!” Zhang Lin wiped the fingernails with a sterile cotton swab. “The extracted skin tissue fragments have a DNA profile that matches the fingerprints on the fire hydrant box, which means the deceased grabbed that unknown man before he died!”
The deceased's blood type test results came back: type A, matching the bloodstains in the bedroom. "That matches up," Zhang Lin noted in the autopsy report. "The bloodstains in the bedroom belong to the deceased. He lost blood after being struck with a blunt object, and the murderer wiped the scene but didn't clean it properly." He cut open the femoral artery; the rupture in the vessel wall was oblique. "This was caused by a sharp object, not a blunt object injury. This means that in addition to blunt force trauma, the deceased was also cut by a sharp object, but the wound was covered by clothing and not found during the external examination."
Regarding the final confirmation of the time of death, Zhang Lin synthesized all the indicators: "Rigidity was completely relieved in the jaw and face, partially relieved in the neck, and there was still mild stiffness in the joints of the limbs, which are characteristics of death 48-72 hours ago. However, after correction for the low-temperature environment, the actual time of death should be 36-48 hours ago." He pointed to the cornea of the corpse, "The turbidity is grade II, the pupil is still visible, and combined with the potassium ion concentration of 6.8 mmol/L in the vitreous fluid, the final time of death is locked between 11 pm on July 3 and 1 am on July 4. These findings currently perfectly match the time window when the surveillance was disrupted."