Forensic cadaver

2021-07-04 11:08 PM

It has been determined that after death, the water in the cadaver will be gradually lost through evaporation at the cadaver surface, causing the weight of the cadaver to decrease. Average weight loss 1kg per day.

An autopsy is the study of all matters related to death, originating from forensic autopsy, and is considered the foundation of criminal medicine.

Death is a phenomenon of irreversible cessation of nerve, respiratory, circulatory functions and then the destruction of body tissues due to no longer being nourished. Therefore, it is necessary to determine whether the victim is dead or not so that the next tasks of forensic work can be carried out.

Verification of death

Verification of death to confirm irreversible shutdown of the nervous, respiratory, and circulatory systems.

Simple method

Nervous system test:

The nervous system must lose all perception, sensation, and reflexes such as asking, not speaking, calling without saying, pinching, or using other types of stimuli that affect the body but do not respond (touching eyelashes, shining light). into the eye the pupil does not constrict...), loss of swallowing reflexes, coughing, and dilated pupils.

Check the respiratory apparatus:

Put cotton in both nostrils, do not see cotton moving, put a mirror in front of the nose without blur, see the chest is not moving, hear no alveolar murmur.

Check the circulator:

When I put my hand on my left chest, I can't see the heartbeat, I can't see the pulse, I can't hear the heart sound.

Other methods

Under technically favorable conditions, we can use the following methods to confirm death:

Incision of the radial artery:

After incision of the radial artery, if dead, the blood does not flow in waves and the artery does not constrict, if alive, the signs are opposite.

Ether test:

Inject 2ml of ether under the skin, if it is still alive, the drug penetrates into the tissues, when the needle is removed, the drug does not flow through the needle hole, a few minutes later, the smell of ether is smelled in the nose. If dead, the injection site will swell, and the medication will be sprayed forcefully through the insertion hole.

Icard's test:

Intravenous fluorescein solution (Pluorescein ammonia 4g+20ml distilled water), if the circulatory system is still active, 10-30 minutes later, the cornea will be iridescent green banana color and after 2 hours the urine color will be visible. luster gold.

Acid reaction:

In principle, after the death of acid-enhanced tissues, color indicators are used to check for such changes. Proceed, use bromothymol color indicator to insert into the needle and pierce the muscle, after a few minutes pull out the needle, the thread will be pink, or use a probe needle, suck a little liver tissue to test with Tournesol paper will appear blue.

EEG recording:

On paper tape, the brain waves are a straight line.

Electrocardiogram recording:

Electrocardiographic waves represent a straight line.

Signs after death

The following signs of early death

Freeze the corpse:

When dead, the organs stop working and no longer produce energy, but after death touching the corpse still feels hot, that heat is the amount of energy left by the body when alive. This amount of energy will gradually lose, on average in the summer, every hour decreases from 0.5 to 10C and in winter it decreases from 1 to 1.5C. The rapid or slow decrease in temperature depends on the body fat or thin, the clothes thick or thin, the corpse indoors or outdoors. The order of temperature of the cadaver began to decrease from the head, face, extremities, then to the base of the extremities, then to the armpits, abdomen, and perineum. To determine the time of death, Scotland's security agency has developed a time calculation based on the decrease in temperature of the body:

Time after death = (37 0 C – T 0 )/1.5 0 C 

Where: 37 0 C is the average temperature of the living body.

T 0  is the temperature of the cadaver at autopsy, taken rectally.

1.5 0 C is the average body temperature per hour lost.

For example: At the time of autopsy, the body temperature was measured at 25°C, so we can determine that the time of the deceased victim is 8 hours from the time of autopsy.

Weight loss:

It has been determined that after death, the water in the cadaver will be gradually lost through evaporation at the cadaver surface, causing the weight of the cadaver to decrease. Average weight loss 1kg per day. Because of dehydration, the cornea becomes cloudy, the eyeball collapses, and the lips and skin wrinkle. For live skin lesions such as: rubbing, pressing, dehydration, a forensic image is called skin cover, meaning this place is dry gray, solid, difficult to cut.

Corpse marks:

Cavity stains are pigmented spots or patches that appear after death because after death the blood does not clot and gradually settles in the lower areas of the cadaver. Hemoglobin penetrates the tissues in those places, at first forming only pink spots, then forming patches of light purple and then dark purple. It is worth noting that the places that are pressed or pressed do not appear faded (belts, bras...).

corpse marks appear 2 hours after death, in the first time, if you change the position of the corpse, the stain will also change. Over 10 - 12 hours after death, the stains are fixed, although the corpse changes, the stains do not change accordingly. For example: When a corpse is lying on its back, the stain will appear on the back of the body, if after 10 hours of turning the body upside down for a while, it will still be on the back, not on the front of the body. 

Thus, the position of the corpse marks reflects the position at the time of death, which is a very important sign for us to know if there is a change in the body's position. In addition, there are a few more features that we need to pay attention to:

The corpse appears early and has a dark purple color in cases of suffocation.

Fades pale pink when dead in liquid.

Bright red (lotus color) when poisoned with carbon oxide (CO), cyanhydric acid (HCN) and its salts (cassava poisoning) and poisoned with Bacbituric sleeping pills.

Rigid cadaver:

After death, the enzyme ATP (Adenozine Triphosphate) of the degraded organization releases lactic acid, which coagulates the protein of the muscle fibers, causing the muscle to contract and lead to rigidity. The phenomenon of muscle spasticity is determined in the following order: The muscles in the face (muscle chewing), in the trunk, extremities and smooth muscles in the viscera. Newborns, the elderly and weak, people who die in an infectious state, exhaustion, and hardening occur very slowly and rarely. Normally, when the corpse is placed on the back, the natural contraction position is: The hands are slightly pressed against the ribs, the legs are stretched.

Hardening occurs about 2 hours after death and can last up to 48 or 72 hours. In cases of suffocation or struggling before death, rigor mortis occurred earlier. Within 2 to 6 hours, if it breaks hard, it will appear hard again. After 6 hours, if the hardening is broken, the hardening does not appear again. This is also an important sign to detect if there is physical contact (in the case of fake crime scenes).

The following signs of late death

Late signs often manifest as spoilage. The spoilage depends on the environmental conditions, the body. In cases of sudden death, cold weather, decay occurs more slowly. In cases of hot weather, death due to blood infection, the spoilage occurs faster.   

Table of contents:

The starting point of the green plaque is in the right iliac fossa and then spreading to the left iliac fossa throughout the abdomen, chest, back, and extremities. Green plaque is formed by anaerobic bacteria that produce hydrogen sulfur gas (H2S) pushed into the blood near the surface of the skin and combined with hemoglobin (Hemoglobin) to form sulfhemoglobin which is green. The green will gradually turn greenish-brown, purplish brown and then black.

Rottenness:

When the green mark spreads to the whole body, the corpse is stretched, the face is deformed, the cuticle gradually peels off, the fingernails and toenails loosen, the hair falls out (hair and nails are not damaged), the internal organs are broken along with the growth of fungi, maggots, bugs... at the surface of the skin, the decay gradually disintegrates the software. Finally, the skeleton and teeth will have the phenomenon of decay (momie) usually over 5 years.

Preservation of corpses

Nature conservation

The corpse lies outdoors, in a very dry atmosphere, or if the sun is strong, it can dry out, that is natural embalming. If buried in very dry or sandy soil, the corpse is preserved naturally, just as the corpse is buried in ice and snow.

Artificial conservation

To keep the corpse from decaying, people often inject strong disinfectants such as formol, phenol, alcohol directly into the arterial system after death, and then continue to preserve it in the environment. suitable as a formal solution or a closed coffin (keep at low temperature), the body will be intact and long-lasting. In dry corpses, mummies, hard wrinkled skin, organs atrophy but keep their shape (in China, corpses buried for 2000 years with a depth of 20 m, microbiological and anatomical tests are also done pathological).

Estimated time of death

Estimating the time of death is important to help law enforcement easily and quickly track down the culprit in murder cases or find the victim's whereabouts in unknown cases. This estimate is approximate only and is based on the markings on the body as well as the markings at the scene where the body was discovered.

The cooling of corpses

The armpits, abdomen, and perineum are the last areas to cool down. The carcass is still warm, not hard, or not completely dead, less than 12 hours. The abdomen is still warm to the touch of the dead for less than 24 hours. The corpse is cold and hard, turning the corpse into purple patches, the death interval is from 24-36 hours. Or you can use the Scottish security agency's time formula.

Dead body

2 hours ago did not show up. From 2 to 10 hours is not fixed (semi-permanent). More than 10 hours after the death is fixed.

Rigid corpse

The victim died less than an hour before the body was solidified. From 1 to 2 hours, the corpse is hard at the head. From 12-24 hours, fully harden. Loss of hardening occurs about 36 hours is a sign of spoilage.

Rotten corpses

A green spot in the right pothole is a sign of decay, it appears after 24 hours in summer and 36 - 48 hours in winter. The green spot spreads to the whole abdomen about 48-72 hours. The whole body is swollen, the skin is peeling and rotten full of green and succulent patches. The victim dies about 1 week in the summer and 1-2 weeks in the winter.

Substance in the stomach

The contents of the stomach reflect the digestive state of the body when alive, people rely on the type of food and the consistency of the food to determine the time from the last meal to death:

Water stays in the stomach for about 1 hour.

Porridge stays in the stomach for about 1 to 3 hours.

Rice or other solid foods stay in the stomach for 4 to 6 hours.

The rice has not been pureed, indicating that the stomach is less than 3 hours.

Pure rice indicates that it has been in the stomach for more than 3 hours.

Supernatural reflexes

Muscle reflexes:

The muscle buoyancy reflex persisted for 6-8 hours after death. Tightening the shank of the knife into the biceps brachii or quadriceps muscle will result in a firm mass along the tight line. For those who are fat, it is necessary to expose the muscles then proceed.

Sweat reflex:

Injecting acetylcholine or pilocarpine subcutaneously, after 40 to 60 minutes, sweat will appear on the skin surface at the injection site. This reflex persists for 6 hours after death.

Pupil dilation and contraction reflex:

Intramuscular injection of acetylcholine or pilocarpine conjugates results in pupillary constriction. This reflex persists for 14 hours after death.

Injecting under the adrenaline conjugate membrane will cause the pupil to dilate. This reflex persists 17 to 19 hours after death.

Biomarkers and the scene

In murder cases, when the body is fresh or not completely spoiled, these signs are the basis for estimating the time of death. However, in the case of decay that has disintegrated the corpse, the above signs are no longer valid and one must rely on the signs on the scene, the insect army destroys the corpse, depending on the time. point of the spoilage process that has different types of insects.

For example, the life cycle of a fly is as follows:

The stage from hatching to larva takes about 2 days.

The larva to pupal stage lasts about 12 days.

The stage from pupa to the development of a fly lasts about 14 days.

If the pupa is found on the corpse, the time at least the corpse has been present at the scene is 28 days.

Lice can live on corpses for about 6 days. If the lice are found dead, the time of death of the victim is more than 6 days.

In addition, people also consider the date in the press, letters from the victim. Examining the footprints on the scene, the sand drifted onto the corpse. Based on the chlorophyll change of the grass where the cadaver was overlaid, chlorophyll is normally lost after 8 days or based on the decay or regeneration of the vegetation at the scene to estimate the time of death.