Detective common sense.

First, the black spots on the bones of the deceased are usually traces of lead sulfide, which proves that the deceased had been exposed to a large amount of lead-containing dust poison before his death.

Second, 90-95% of lead invading the body will form insoluble lead phosphate, which will be deposited in bones.

3. Because the nameless corpse sinks to the bottom of the pond, the hydrogen sulfide gas produced by the sludge and corpse decay in the pond reacts with the lead deposited in the bones to produce lead sulfide, thus forming black bone spots.

Fourth, the content of salt in human blood far exceeds that in animal blood.

The high tide and low tide of seawater always change in turn every six hours.

6. Usually when we open the door with the key, we use the thumb and forefinger, but the forefinger is not the fingertip part, but the part next to the joint, which is attached to the handle of the key, so that the key can be turned, so we should leave the thumb fingerprint on the handle of the key, not the forefinger fingerprint.

Seven, usually when riding a bicycle, the weight of the rider is added to the rear wheel; Therefore, on a flat road or downhill, the traces of the front wheels are shallow and the traces of the rear wheels are deep. However, when going uphill, due to the strength of the cyclist, the center of gravity is between the pedal and the handle of the bicycle, and the trace depth of the front wheel and the rear wheel will be exactly the same.

Eight, if a person dies of cyanic acid, because cyanic acid is different from other poisons, it will not destroy the nervous system in cells, nor will it be circulated by acidic substances in the blood, so pink that will change the color of blood will look better. Moreover, cyanic acid poisoning will make the mouth have a special smell.

Nine, how to distinguish the time of death of the body?

1. According to the stiffness of the corpse, under normal circumstances, the corpse will be hardened within 30 minutes to 2 hours after death, completely stiff within 9 hours to 12 hours, softened after 30 hours, and restored to its original state after 70 hours. But if it is in soil or water, or under low temperature and dry conditions, it will be delayed and accelerated under high temperature and high humidity conditions.

2. Look at the changes in the body

(1) Finger pressure: Death spot is a special place where blood gathers under a corpse due to the principle of gravity.

After death, pressing the finger for 6- 12 hours will fade somewhat, but it will not fade after 12 hours.

(2) Displacement: If the corpse has been moved, the corpse spot will be displaced, but if the body position is changed 8-9 hours after death, the corpse spot will only partially move, and the old corpse spot will still exist, and new corpse spots will also appear. After 1 0 hour, the lividity stopped moving.

(3) Note: The age, physique, cause of death and environmental factors of the deceased need to be considered, and different factors will produce great differences.

Usually, the following formula is used to infer the time of death: normal body temperature (98.6 of)- rectal temperature of the corpse /l.5= approximately the elapsed time after death.

3. Look at the digestion in the corpse again. The food will reach the small intestine after being digested by the stomach for about 2 hours.

Traditionally, there are three methods to estimate the time of death: rigor mortis, lividity and temperature. Detective novelists often use this inference to describe stories vividly, so don't believe it completely. Because the phenomenon after death is influenced by many factors, such as the temperature of the environment, the physique of the corpse, the degree of exercise, whether to drink alcohol, whether to use anesthetics and so on.

The appearance of necrophilia also has a certain time law. After death, blood circulation stops. After half an hour at the earliest, the blood fell to the blood vessels at the bottom of the body due to its own gravity, and the skin there showed purple spots, like red wine at the bottom of the bottle. This is necrophilia. Lividity appeared within 4 10 hour at the latest after death. Its color lasts for a long time. If a person lies on his back after death, the corpse spot should be on his back. If lividity is found in the front of his body, it means that the body has been moved.

4. Look at the degree of decomposition of the body

The third aspect is to judge the time of death by the temperature of the body. After death, the body stops generating heat, and the temperature of the body will drop by about 65438 0 degrees per hour. The temperature of muscle tissue and environment has great influence on the temperature of corpse. The body temperature of fat people drops more slowly than that of epidemic patients. The temperature of a corpse in a warm room is slower than that in a cold room.

The face and limbs were cold, and lividity and rigor mortis began to appear. The time of death was 1 ~ 2 hours.

Lividity is distributed in fragments, and rigor mortis mostly appears, and the death time is 3 ~ 4 hours.

Necrophilia merged into a large area, the whole body appeared stiff, the cornea was slightly turbid, and the lips began to shrink. After dropping eye drops with mydriatic agent and mydriatic agent, the pupil still reacted and the death time was 5-6 hours.

Rigor is highly developed, the dead point can be completely subsided by finger pressing, the cornea is highly turbid, and the conjunctiva begins to dissolve on its own. The time after death is about 12 hours.

Necrophilia can completely subside, parchment-like spots are formed, the cornea is highly turbid, scleral dark spots appear, and oral mucosa and conjunctiva autolyse. The time after death is about 24 hours.

The occurrence time of the above-mentioned postmortem phenomena is based on spring and autumn, which accelerates in summer and slows down in winter.

Corrupt abdominal distension begins at 8 ~ 10 hour after death in spring and autumn, 4 ~ 5 hours after death in summer and 48 ~ 72 hours after death in winter.

Corrupt green spots appear about 24 hours after death in spring and autumn, 12 hours after death in summer and 72 ~ 120 hours after death in winter.

Corrupt vascular network appeared 48 ~ 72 hours after death in spring and autumn, 65,438+0 ~ 2 days after death in summer and about 7 days after death in winter.

Hair is easy to fall off and appear rotten blisters, which appear 3 ~ 5 days after death in spring and autumn, 1 ~ 2 days after death in summer, and generally do not appear rotten blisters in winter.

The concept of corrupt giant began to appear 3 ~ 7 days after the death of Spring and Autumn, 2 ~ 3 days after the death of summer, and 15 ~ 30 days after the death of winter. In midsummer, it takes about a month for the soft tissue of the corpse to liquefy and disappear, and the time will be shortened in the case of fly injury. If the body is in the water, there are still some postmortem phenomena to infer that the skin of hands and feet is soft, swollen, white and dry at the time of death. If it appears on the palms and soles of the feet, the time of death is about 4 hours; If it appears on the back of hand and instep, the time of death is about 48 hours.

The phenomenon that the skin of hands and feet falls off like gloves, if it appears on a corpse in summer, its death time is about one week; Winter is about January; Spring and autumn days are about 2 weeks.

The concept of corrupt giant appeared in the spring and autumn of 7 ~ 10 days after death, 4 ~ 5 days in summer and1.5 ~ February in winter.

It needs to be emphasized again that the occurrence and development of postmortem phenomena are restricted by various conditions. When judging the specific time of death of the deceased, we should analyze and speculate according to specific problems, and we must never mechanically copy any data.

Stomach food has its unique significance in forensic medicine. Forensic workers can not only infer the eating area, living habits and economic situation of the deceased according to the types and components of food in the stomach, but also provide clues for investigation and solving crimes; According to the degree of digestion and emptying of food in the stomach, we can infer the approximate time from the last time the deceased ate to his death, which provides a scientific basis for inferring the time of death and the range of activities of the deceased before his death.

Practice shows that the degree of digestion and emptying of food in the stomach depends on the nature of food. Take rice and vegetables for example. If the appearance of rice vegetables is complete, chyle is reduced, and only a small amount of food enters the duodenum, they should generally die within 1 ~ 2 hours after meals. If the food in the stomach is chyle, only a few grains of rice and vegetable residues, the food has entered the large intestine and will die about 4 hours after meals. All the food in the stomach has been emptied, or only hard vegetable skins such as coarse skin fiber and kelp skin are left, so you will die 4-6 hours after a meal. If the contents of the stomach are meat or greasy and indigestible food, the time from eating to death should be extended accordingly.

To infer the time from eating to death by using the digestive emptying degree of stomach contents, two factors should be fully considered: first, different people's digestive ability and the intestinal propulsion speed of food are different; Second, gastrointestinal peristalsis and digestive enzymes will continue for some time after death, so that food can continue to digest. This situation is more obvious when the body temperature drops slowly.

Estimation of time of death based on bladder urine volume.

People who die at night can also estimate the time of death according to the filling degree of urine in the bladder. According to the habit of ordinary people, you should urinate before going to bed. If you see little urine in the bladder at autopsy, you may die within 2 ~ 3 hours after sleep. If you urinate heavily, you may die in the middle of the night. It's just that this situation is accidental, so it can only be used as a reference, not just to judge the time of death.

Generally speaking, the occurrence and development of postmortem phenomena are greatly influenced by internal and external factors. All materials should be combined for objective analysis.