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

Chapter 1142 Determining the Time and Cause of Death

Secondary opacity occurs within 48-72 hours, at which point the corneal stroma begins to swell, resembling a layer of frosted glass. However, in water at 16°C, corneal moisture evaporation is 40% slower than at room temperature, thus delaying the opacity process. Therefore, the actual timeframe is approximately 12 hours later than the baseline at room temperature.

Zhang Lin gently pinched the deceased's index finger with tweezers. The skin at the knuckles had lost its elasticity and exhibited a waxy hardness. "The skin at the knuckles is beginning to show leather-like characteristics, especially at the interphalangeal joints." He measured the skin thickness with a ruler. "Normal skin thickness is about 1mm, but here it has reached 1.5mm. The moisture in the dermis has been replaced, and the collagen has coagulated. In an aquatic environment, leather-like characteristics appear 24-36 hours later than in air. This level of hardening corresponds to more than 72 hours after death, but it has not yet reached the stage of severe leather-like characteristics—if it exceeds 120 hours, the skin at the knuckles will become brittle like cardboard and easily break."

The test results of the stomach contents were placed on a tray beside him. The centrifuged liquid clearly separated into layers: a pale yellow oil on top, a cloudy chyme in the middle, and a bottom layer of rice and vegetable fragments. "Considering the degree of digestion of the stomach contents, the rice grains still retained their intact shape, and the broken surfaces of the vegetable fibers were relatively neat," Zhang Lin observed the sample under a microscope. "The hydrolysis rate of the starch granules is about 30%, which is typical 3-4 hours after eating. Generally speaking, the gastric emptying time for mixed foods is 4-6 hours. Rice and vegetables are easily digestible foods, so their emptying rate is faster. Assuming the deceased ingested these foods at dinner, and considering death occurs 3-4 hours after a meal, the time of death should be shortly after dinner, that is, after 8 pm."

He turned and wrote down the formula on the calculation paper, his pen drawing clear lines: "The impact of low-temperature water (16°C) on the decomposition process needs precise correction." He pointed to the coefficients in the formula, "At a normal temperature of 25°C, the decomposition rate of a corpse in water is 0.7 times that in air, while the water temperature of 16°C is 9°C lower than normal. For every 1°C decrease, the activity of putrefactive enzymes decreases by 5%, and the overall decomposition process is slowed down by 30%." He circled several key data points on the paper, "The rate of rigor mortis resolution, the degree of corneal opacity, and the progress of leather-like formation—these three indicators all need to be multiplied by a correction factor of 1.3."

Zhang Lin added other auxiliary indicators: "The deceased's hair began to fall out slightly, especially at the temples. Three to five hairs could be removed with a gentle pull, a characteristic of 72 hours after death—osmotic pressure in the water would damage the connective tissue of the hair follicles, but low temperature would slow down this process. Although the fingernails had not yet fallen off, a gap of 0.5 mm appeared between the nail bed and the nail plate, which usually appears around 96 hours after death." He picked up a fingernail sample. "The amount of silt deposited under the nail plate can also help determine the cause. The deposit thickness is about 0.2 mm, and based on a water flow rate of 0.05 mm per day, the deposition time is exactly about 4 days."

The most crucial correction came from adjusting the digestion time of stomach contents. "Normally, death occurs 3-4 hours after a meal, and the stomach contents remain in this semi-digested state. However, in a low-temperature environment, gastrointestinal motility slows down, the activity of digestive enzymes decreases by 20%, and the digestion process is prolonged by 1-2 hours." Zhang Lin added this variable to the formula. "Therefore, the actual time of death after a meal should be 4-5 hours, not 3-4 hours at room temperature. We retrieved the operating hours of surrounding restaurants; the dinner peak is usually from 6 pm to 8 pm. Calculating based on the latest eating time of 8 pm, 4-5 hours later would be from midnight to 1 am."

综合所有数据，张林在计算纸上画出一条曲线，横轴是死亡时间，纵轴是各项指标的数值。曲线在5月9日晚8点至5月10日凌晨2点之间形成一个密集的重叠区域。“角膜混浊校正后对应死亡84-96小时，皮革样化对应72-96小时，毛发脱落和指甲变化对应96-120小时，胃内容物消化时间校正后指向午夜12点至凌晨1点。”他用红笔在这个区间画了个框，“再加上低温水体的30%延缓系数，最终死亡时间应该锁定在5月9日晚8点至5月10日凌晨2点之间，误差不超过6小时。”

Xiao Lin took notes, his pen moving rapidly under the heading "Cross-verification of Error Ranges for Various Indicators." Zhang Lin's gaze fell on the corpse's calves, where faint green patches were visible on the skin—the initial signs of cadaveric greening. "Cadaveric greening usually appears 24-48 hours after death, but in cold water it can be delayed until 72 hours. The patches here are only 3x2cm, indicating they formed recently, further confirming our time estimate." He closed the calculation paper; the formulas and curves on it resembled a finely crafted net, firmly ensnaring all clues within that timeframe of death.

The crucial factor of determining the cause of death has become controversial. During the heart examination, Zhang Lin found a small amount of mud and sand in the right ventricle, and minor bleeding points in the myocardial tissue. "Asphyxiation from drowning is the primary cause of death," he said, gently opening the right ventricle with hemostats. "But a laceration to the head could also be fatal—the wound reached deep into the skull, and although it didn't cause a skull fracture, it could have led to intracranial hemorrhage." Xiao Lin suddenly pointed to the mud and sand in the wound cavity: "Was this mud and sand in there before death, or was it washed in by the water flow after death?"

“The mud and sand that entered the body before death will mix with blood,” Zhang Lin observed the sample under a microscope. “Hemoglobin is attached to the surface of the mud and sand particles here, indicating that the injury occurred before death and that the patient was still alive after the injury.” He asked Xiao Lin to extract skin tissue from the wound edge, “to do a tissue section examination to see if there is an inflammatory reaction. If there is, it means that the patient survived for a period of time after the injury; if not, it may have been caused during the dying period or after death.”

The autopsy continued late into the night, and by the time the last suture pierced the skin, Zhang Lin's forehead was covered in sweat. "The preliminary cause of death is drowning and asphyxiation, but the possibility of a head contusion and laceration accelerating death cannot be ruled out," he wrote in the autopsy report. "The weapon used to injure the victim was a blunt instrument, possibly gravel or bricks from the culvert; the time of death was between 8 p.m. on May 9 and 2 a.m. on May 10; the victim had been restrained before death, showing signs of both drowning and head trauma, which perfectly matches the drag marks and restraint residue found at the scene."

While sorting through the evidence, Xiaolin suddenly pulled a metal piece from the victim's jacket pocket. The piece had the blurry number "37" engraved on it. "This might be some kind of serial number," she said, holding the piece up to the light. "It's made of brass, and the surface is worn; it must have been used for a long time." Zhang Lin took the metal piece and suddenly remembered the nylon rope found at the scene.