Forensic Thanatology

It deals with death in all its aspect i.e mode of death, manner of death & causes of death



Death is permanent and irreversible cessation of functions of the 3 interlinked vital systems of the body (theTripod of life) namely, the nervous system, circulatory system, circulatory system and respiratory system.


Medical Classification of Death:

1. Somatic/systemic/clinical death

It is the complete and irreversible cessation of functions of nervous, circulatory and respiratory systems

Medico-legal importance of somatic death:

1. For declaration of death

2. For organ or tissue transplantation

3. For death certificate

4. For taking decision whether artificial respiration or circulation should be continued or not.


2. Molecular/cellular death

It means death of the individual cells of the body which takes place usually 1-2 hours after the stoppage of the vital functions.

Individual cells will live on their residual oxygen for a variable time after the circulation has stopped. Cells have storage of ATP which they utilized to continue their metabolic activity. After 1-2 hours, stored ATP will be finished and the subsequent changes occur due to metabolic dysfunction resulting in structural disintegration.

Nervous tissues die rapidly, the vital centers of the brain in about five minutes, but the muscles live up to one to two hours.


Medico-legal classification of Death:

1. Natural

2. Suicidal

3. Homicidal 

4. Accidental



It indicates the circumstances under which the person died.

The way (or design/fashion) in which the cause of death comes into being.

A. Natural

B. Unnatural

 1. Suicidal

 2. Homicidal

 3. Accidental


Difference between molecular death & somatic death

Somatic Death

Molecular Death

It is the complete and irreversible cessation of functions of nervous, circulatory and respiratory systems

It means death of the individual cells of the body.

Also called as clinical death/systemic death

Also called as cell death

Immediately occur after the permanent & irreversible brain death & cessation of heart & lung function.

Usually occur at 1-2 hours after the somatic death.

Occur due to clinical/pathological  condition leading to permanent cessation of nervous, circulation & respiratory system.

Occur after somatic death due to unavailability of oxygen.



Diagnosis of Somatic Death (Immediate changes after somatic death)

Insensibility, Loss of Movement and loss of EEG rhythm for a continuous period of 5 minutes.

Complete stoppage of respiration for more than 5 minutes

Stoppage of heartbeat for more than 5 minutes (Flat ECG)


How molecular death can be conformed?

Between the time of  somatic death & before the onset of molecular death, following phenomenon can be observed.

1. Pupil react to the miotic & mydiatric agents but do not react to strong light.

The pupils react to atropine and eserine(physostigmine) for about an hour after death but they do not react to strong light.

2. Muscular irritability and response to mechanical or electrical stimuli persist.

Primary Flaccidity/relaxation: During this stage, death is only somatic (no cellular death) and it lasts for one to two hours. All the muscles of the body begin to relax soon after death.

Muscles are relaxed as long as the ATP content remains sufficiently high to permit the splitting of the actin-myosin cross-bridges. Muscular irritability and response to mechanical or electrical stimuli persist. Peristalsis may occur in the bowel, and ciliary movements and movements of white cells may continue.

Normal relaxation in life is achieved by energy-dependent (ATP-driven) pumping of calcium back across the membrane of the sarcoplasmic reticulum, but this fails after death because of membrane disruption and lack of ATP, due to which increased calcium level in the sarcomeres causes muscle contraction.

When the ATP is reduced to a critical level (85% of the normal), the overlapping portions of myosin and actin filaments combine as rigid link of actomyosin, which is viscous and inextensible, and causes hardness and rigidity of muscle rigor.

The rigidity of the muscle is at its maximum, when the level of ATP is reduced to 15%.


Mechanical excitability of skeletal muscle:

1.  Tendon reaction or Zasko's phenomenon:

Striking the lower third of the quadriceps femoris muscle about I0 em. above the patella with a reflex hammer causes an upward movement of the patella because of contraction of the whole muscle. This can be seen up to 1 to 2 hours after death. It seems to be a propagated excitation of muscle fibres.


2.  Idiomuscular contraction or bulge:

Striking at the biceps brachii muscle with the back of a knife causes a muscular bulge at the point of contact due to local contraction of the muscle.


Molecular dead can be conformed by

1. Pupil does not  react to the miotic & mydiatric agents

2. Absent of mechanical excitability of skeletal muscles. No zasko’s phenomenon & Idiomuscular contraction seen.

3. Already establishment of Rigor Mortis(cadaveric rigidity) phase

4. In the phase of Cooling of the body (Algor Mortis):

For about half to one hour after death, the rectal temperature falls little or not at all (postmortem temperature plateau). This is followed by a linear rate of cooling (between0.4to 0.6°C per hour) for the next 12 to 16 hours.


Bishop’s Tripod of Life:

Life depends upon the integration of three interlinked vital systems i.e. respiration, circulation & nervous system called Tripod of Life.

If any of these three systems fails, then other two also will fail (as they are functionally interlinked).


Modes of death:

Indicate from which vital system the process of death initiate irrespective of cause of death.

According to Bichat, there are three modes of death, depending on whether death begins in one or other of the three systems, irrespective of what the remote causes of death may be.

The process of death may be initiated by failure of any of the three vital system of the body.


Failure of nervous system


Failure of circulatory system


Failure of respiratory system



The terms, Coma, Asphyxia, Syncope indicate Mode of Death, rather than causes of Death.



Asphyxia is a condition caused by interference with respiration, or due to lack of oxygen in respired air, due to which the organs and tissues are deprived of oxygen (together with failure to eliminate CO2),

causing unconsciousness or death.


Bain uses 20% of total available oxygen. Nervous tissues are affected first by deficiency of oxygen and their functions are disturbed even by mild oxygen lack. The neurons of the cerebral cortex  will die in 3 to 7 minutes of complete oxygen deprivation. Irreversible cortical damage may occur if oxygenated blood fails to perfuse the brain up to 7 to 9 minutes.


The rule of thumb is: breathing stop within twenty seconds of cardiac arrest, and heart stops within twenty minutes of stopping of breathing.



Syncope is sudden stoppage of action of the heart, which may prove fatal.This term is also not used as a cause of death.

Syncope or fainting is due to vasovagal attacks resulting from reflex parasympathetic stimulation. Syncope is caused by reflex bradycardia or asystole, or by reflex splanchnic vasodilation. Due to the acute reflex circulatory changes, blood pressure falls suddenly causing cerebral anaemia and rapid unconsciousness. Recovery is common.


In syncope, there is failure of function of the heart and the circulatory system.

With circulatory collapse , there is rapid, weak or slow pulse, fall of blood pressure.



It is a state of unarousable unconsciousness determined by the absence of any psychologically understandable response to external stimuli or inner need. It involves the central portion of the brain stem. Coma is a clinical symptom and not a cause of death.

Synonyms of Arouse - awaken, stimulate, alert, excite


Coma means loss of consciousness which may be partial or complete, depending on the degree of involvement of the central nervous system.


 Types of tissue and organ transplantation


Homologous donation

Grafting of tissue from one part of the body to another part of the same person. E.g skin, bone


Live donation

Transplantation from one person to another living person i.e., blood transfusion, bones, kidney and part of liver transplantation


Cadaveric donation

Transplantation of organs from a dead person.

Most of organs must be obtained while the donor's heart is still beating to improve the chance of success.




Heart, lung, kidney, liver, pancreas

Soon after circulation has stopped


Within 6 hours


Within 24 hours


Within 48 hours

Arterial graft

Within 72 hours

Organ is transplanted only from living cadaver.


Brain Death

It means the permanent and irreversible cessation of function of the brain, but the functions of other vital organs may intact by any artificial way.


1. Cortical or cerebral death (persistent vegetative state) 

with an intact brain stem. This produces a vegetative state in which respiration continues, but there is total loss of power of perception by the senses.


2.Brain stem death

Cerebrum may be intact, though its function is cut off  by the brainstem lesion. The loss of the vital centers that control respiration, and of the ascending reticular activating system that sustains consciousness, cause the victim to be irreversibly comatose and incapable of spontaneous breathing.


3. Both cortical and brainstem death (Whole Brain Death)

 Permanent cessation of function of cerebrum, cerebellum, brain stem



According to Harvard Criteria:

1. Unreceptivity and unresponsivity:

 Total unawareness to externally applied stimuli and inner need and complete unresponsiveness to even the most intense painful stimuli.

2. No movements:

No spontaneous muscular movements in response to stimuli such as pain. touch, sound or light for a period of at least one hour.

3.  Apnoea:

Absence of spontaneous breathing for at least one hour

4. Absence of elicitable reflexes:

Irreversible coma with abolition of central nervous system activity is evidenced in part by the absence of elicitable reflexes.

The pupils are fixed and dilated and do not respond to a direct source of bright light.

Ocular movement and blinking are absent. There is no evidence of postural activity. Corneal and pharyngeal reflexes are also absent. Stretch tendon reflexes also cannot be elicited.

5. Isoelectric EEG (Electro-encephalogram):

Flat EEG. It has confirmatory value.


All these tests should be repeated after 24 hour with no change. Further it is stressed that the patient be declared dead before any effort is made to take him off the ventilator, if he is then on a Ventilator. This declaration should not be delayed until he has been taken off the respirator and all artificially stimulated signs have ceased.


Brainstem death

It is type of brain death in which there is permanent cessation of function of the brainstem but the cerebrum may remain intact although its function is cut off by the brainstem lesion.

If the brainstem is damaged due to trauma, cerebral edema, hemorrhage, hypoxia or infection, such as poliomyelitis, respiratory motor system fails and damage to the ascending reticular activating system causes permanent loss of consciousness, and higher centers in the cortex are also irreversibly damaged causing 'Whole Brain Death'.


Function of Brainstem

Brainstem enables the cerebral hemispheres to work in an integrated way. Damage to the ascending reticular activating substance or damage to areas of the cerebral hemispheres results in disturbance of normal consciousness. If this area is dead, the person is irreversibly unconscious and apnoeic (incapable of breathing).

The brainstem is also responsible for the respiratory drive, and in large measure (but not exclusively) for the maintenance of blood pressure.

 All motor output from the brain travel through the brainstem.

 Apart from vision and smell, all the sensory traffic coming into the brain arrives through the brainstem.

 The brainstem also mediates the cranial nerve reflexes.


Brainstem reflexes:

1. Pupillary reflex

2. Corneal reflex

3. Gag reflex

4. Ciliospinal reflex

5. Oculocephalic reflex (Doll’s Head phenomenon)

6. Vestibuloocular reflex (Vestibular response to caloric stimulation)

7. Tonic neck reflex


Preconditions for diagnosis of Brainstem Death:

 (i) Patient must be deeply comatose.

(ii) Patient must be maintained on a ventilator.

(iii) Cause of the coma must be known.


Exclusions for Diagnosis of Brainstem Death:

(1) Where the patient may be under the effects of drugs, e.g. therapeutic drugs or overdoses.

(2) Where the core temperature of the body is below 35°C.

(3) Where the patient is suffering from severe metabolic or endocrine disturbances which may lead to severe but reversible coma, e.g. diabetes.


Personnel who should perform the tests for Brainstem Death:

1. Brainstem death tests must be performed by two medical practitioners.

2. Doctors involved should be experts in this field. Under no circumstances are brainstem death tests performed by transplant surgeons.

3. At least one of the doctors should be of consultant status. Junior doctors are not permitted to perform these tests.

4. Each doctor should perform the tests twice.


Test to be performed for Diagnosis of Brainstem Death:

Before the tests are performed the core temperature of the body is taken to ensure that it is above 35°C.


The diagnosis of brainstem death is established by testing the function of the cranial nerves which pass through the brainstem. If there is no response to these tests, the brainstem is considered to be irreversibly dead:

1. Pupils are fixed in diameter and do not respond to changes in the intensity of light.

2. There is no corneal reflex.

3. Vestibulo-ocular reflexes are absent, i.e. no eye movement occurs after the instillation of cold water into the outer ears.

4. No motor responses within the cranial nerve distribution can be elicited by painful or other sensory stimuli, that is the patient does not grimace in response to a painful stimulus.

5. There is no gag reflex to bronchial stimulation by a suction catheter passed down the trachea.

6. No respiratory movements occur when the patient is disconnected from the ventilator for long enough to ensure that the carbon dioxide concentration in the blood rises above the threshold for stimulating respiration, i.e. after giving the patient 100% oxygen for 5 minutes. If no spontaneous breathing of any sort occurs within that 10 minutes, the brainstem is incapable of reacting to the presence of the carbon dioxide and is thus dead.



When two doctors have performed these tests twice with negative results, the patient is pronounced dead and a death certificate can be issued.




Medico-legal importance:

For declaration of death

For organ or tissue transplantation

For death certificate

For taking decision whether artificial respiration or circulation should be continued or not.


Causes of death:

Cause of death is the disease or injury responsible for starting the sequence of events, which are brief or prolonged and which produce death.


Cause of death means Reason a person ended up in one of the modes of death.


It may be divided into:


Immediate cause 

Injury or disease present at the time of terminal event e.g., bronchopneumonia, peritonitis, trauma, etc.


Basic cause

Pathological process responsible for the death at the time of terminal events or prior to or leading to the event.

e.g., gunshot wound of abdomen complicated by generalized peritonitis.


Contributory cause

The pathological process involved in or complicating but not causing the terminal event.


According to the autopsy findings:


Natural causes

I. Where a lesion is found at autopsy which is incompatible with life.

 Structural abnormalities found, pulmonary thromboembolism, spontaneous intracerebral hemorrhage, rupture of aortic aneurysm.


II. Where a lesion is found at autopsy which is known to cause death.

But compatible with continued life. Coronary artery diseases, chronic heart disease, lobar pneumonia


Unnatural cause

I. Where a lesion is found at autopsy which is incompatible with life.

Decapitation, avulsion of heart from large vessels, crushing of head


II. Where a lesion is found which may have caused death or which may have precipitated death, but which is also known to be compatible with continued life

their nature, site or extent may not appear to be sufficient to cause death in a healthy person. But such injury may be the cause of death due to some complication resulting directly from the injury,


Obscure cause

I. Where no lesion is found at autopsy or if a lesion found it is of a minimal or indefinite nature.


Suspended animation/apparent death/death trance/catalepsy

In this condition signs of life are not found, as the functions are interrupted for sometime, or are reduced to minimum.However, life continues and resuscitation is successful in such cases.

It is the condition in which person seems to be death but ECG and EEG show signs of life.

Sometimes so happen that the function of the nervous system, circulatory and the respiratory system may not persist by conventional methods though the person may actually not dead and the functions of the systems return after sometime, either as such as after proper resuscitation, such a death like state is known as suspended animation.

No circulation and respiration beat response in ECG and EEG.


Types with the examples/condition:


Practitioners of yoga can pass into a trance, death-like in character.



Involuntary suspension of animation lasting from a few seconds to half-an-hour or more may be found in

A newborn infant

Drowned person




After anesthesia


Several syncope attack


Vagal inhibition

Narcotic poisoning

Cerebral concussion

The patient can be resuscitated by cardiac massage or electric stimulator and artificial respiration.



1. Repeated auscultation over a period longer than 5 minutes for the evidence of cessation of heart beat and respiration

2. ECG

3. EEG

4. Ophthalmoscopy should be done routinely and death is confirmed by electing segmentation of retinal blood vessels.


Medical importance:

1. An alive person may be sent to the mortuary due to confusion of the doctor .

2. A doctor may issue a death certificate though the person remains alive.

3. If precautions are not taken, alive person may be died.


(Persistent vegetative state)

If the cortex alone is damaged, the patient passes into deep coma, but the brainstem will function to maintain spontaneous respiration. This is called "persistent vegetative state" and death may occur months or years later due to extension of cerebral damage or from intercurrent infection.


In this condition the patient breath spontaneously, has a stable circulation and shows cycle of eye opening and closing which may stimulate sleeping and waking but he is unaware to the self and environment.



Whole or part of the brain can be irreversibly damaged due to hypoxia, cardiac arrest, intracranial hemorrhage, poisoning and trauma to the brain.


Diffuse axonal injury

Diffuse ischemic brain damage (cortical brain damage)

Bilateral damage to the neocortex

Diffuse damage to white matter

Bilateral damage to the Thalami



After brain stem death has been established, the retention of the patient on the ventilator facilitates a fully oxygenated cadaver transplant, the so-called "beating-heart donor". The results of the transplant are much improved. This has no legal sanction.


Living cadaver

Living cadaver are those persons in whom ‘brain death’ has occurred but the respiration and circulation are maintained by artificial means.

Importance: this condition is necessary for organ transplantation.


Natural death

Natural death means that the death was caused entirely by the disease and the trauma or poison did not play any part in bringing it about.



It  is the time between a lethal occurrence and death.


Supravital Period or Intermediary Life:

It is the period of survival of some tissues after irreversible circulatory arrest.

The period between somatic death & cellular death.


Presumption of Death

A person is presumed to be dead if he has not been seen for minimum period of 7 years.


Sudden death

Death is said to be sudden or unexpected when a person not known to have been suffering from any dangerous disease, injury or poisoning is found dead or dies within 24 hours after the onset of terminal illness.


Causes of Sudden Death


Diseases of CVS

Coronary atherosclerosis with coronary thrombosis

Coronary artery embolism

Spontaneous rupture of aorta

Pulmonary embolism

Rupture of aortic or other aneurysm

Acute endocarditis

Acute pericarditis

Congenital heart disease in new born


Respiratory System

Air embolism

Lobar pneumonia

Pulmonary embolism and infarction

Lung abscess

Acute oedema of the lungs

Pleural effusion

Bronchial asthma

Impaction of foreign body in the larynx and regurgitation of stomach contents into air-passages and bronchioles

Rupture of blood vessel in pulmonary tuberculosis with cavitation


Central Nervous System

Cerebral, Cerebellar hemorrhage

Cerebral thrombosis and embolism

Brain abscess

Brain tumor




Alimentary System

Hemorrhage into the gastrointestinal tract from peptic ulcer, oesophageal varices, cancer oesophagus


Intestinal obstruction

Obstructive cholecystitis.


Genito-urinary system

Chronic nephritis


Vasovagal Attack/Vasovagal Syncope/Neurocardiogenic Syncope

Vasovagal attack is a condition  resulting from reflex parasympathetic stimulation of vagus nerve  in which there is rapid fall of heart rate & blood pressure due to circulatory collapse/failure resulting in decreased blood flow to brain causing cerebral ischemia & rapid unconsciousness.


Parasympathetic Stimulation causes:

Decrease Heart rate

Fall in blood pressure


Parasympathetic stimulation of the heart can be initiated by high neck compression, pressure on carotid sinus or sometimes by direct pressure over the trunk of the vagus nerve.



A soldier was dancing with his girl friend in the presence of many others in a hall. While dancing, he playfully "tweaked" (pinched) her neck. She dropped down dead on the spot. There were no injuries or signs of asphyxia. Death was as a result of vagal inhibition.


Vagal inhibition of heart (cardiac arrest due to vagal stimulation)

Vagus is a mixed nerve which has motor sup ply to part of the palate, larynx and pharynx and sensory supply to pharynx, oesophagus and rest of the respiratory tract. Among the organs and viscera it supplies are, heart, lungs and stomach.


Stimulation of vagus causes inhibition of the heart. If the heart at that stage is in anoxic condition, then there may be cardiac arrest.

Cardiac arrest of vagal origin is primarily noticed on the operation  table due to insufficient induction or due to low maintenance dose of the anesthetic agent.

Subjects who are oversensitive to vagus are usually prone to such episode. Other vulnerable subjects are those who have carotid sinus overactivity or are thymolymphaticus young boys.

Stimulation of the vagus can cause inhibition of the heart rate in one side and bronchospasm on the other. The heart thus may as well be in a state of anoxia or partial anoxia simultaneously. Thus stimulation of the vagus may quite expectedly cause cardiac arrest.


Some persons may become specially prone when the vagus nuclei are stimulated with painful stimuli carried to the brain through the sensory nerves,  as in cases of being kicked on the scrotum, abdomen or hit by a fist blow over the precordial area of the chest or on the neck or during use of instrument inside the vagina or in the respiratory tract.




Diagnosis the death of a person:

A. Test of circulatory system:

Pulse: absent (radial, brachial, femoral, carotid)

Auscultation: repeated auscultation over the pre-cordial area for >5 minutes

No E.C.G activity


Stoppage of heartbeat for more than 5 minutes is irrecoverable and is accepted as evidence of death.


B. Test of nervous system:

No sense

Loss of sensory and motor function

Loss of superficial and deep reflex

Pupil dilated


C. Test of respiratory system:

Inspection: no respiratory movement

Palpation: no respiratory movement

Auscultation: no breath sound


Complete stoppage of respiration for more than 5 minutes usually causes death.


D. Test of surest signs:





Conditions to be fulfilled to issue a death certificate

1. A doctor should only issue a death certificate

- If he is registered as a qualified medical practitioner

- If he has examined the patient (alive) within the previous 14 days.

- If he must be satisfied that he knows the cause of death and it is definitely due to the natural cause.

2. If he is not sure the cause of death or consider that there are suspicious circumstance or industrial disease then he should not give death certificate.