BURNS
Dr. M. Vidanapathirana
MBBS, DLM, MD, MA, MFFLM (UK)
Senior Lecturer, department of Forensic Medicine,
FOMS, University of Sri Jayewardenepura
Time required to cause a burn
44c x few hours
50c x few minutes
65c x few seconds
750c x 2 ½ hours to cause complete incineration (become ash
and pieces of calcined bones)- eg cremations at crematoriums.
Out come of a burn depends on
Type of burn
Surface area
Depth of burn
Distribution
Patients age, diseases, injuries
Skin thickness x temperature x duration of contact
Skin circulation (If old- due to less circulation out come of the burns is poor. In young
– vice versa.
Presence of inhalation injuries- fumes can kill with minimal surface burns
Classification of burns
1. Thermal burns
2 Chemical burns
3. Electrical burns
4. Mechanical/ Friction burns – will be discussed under
the lecture on abrasions)
1. THERMAL BURNS
1) Definition-
i. Injuries caused by the local effects of heat.
(Cold burns /hypothermic burns? – therefore we need a broad
definition)
ii. Injuries caused by coagulation necrosis of tissues.
Different Types of thermal burns-
SCALD BURNS
FLAME BURNS
FLASH BURNS
CONTACT BURNS
RADIANT BURNS
CHEMICAL BURNS
MICROWAVE BURNS
A. Scald burns
Scald burns are a common form of child abuse. Scald buns –
usually blisters present.
Red/ pale and moist/sodden burns.
As the fluid moves down the body, the burns become
progressively less severe.
Boiling water can cause 3rd degree burns when 158 F X 1 second of
contact. But no charring, carbonization or hair singing.
3 types of scald burnsi. Immersion burns (accidental or
deliberate),
ii. Splash or spill burns (usually
accidental. Some times deliberate,)
iii. Steam burns (by super heated
steam) (usually accidental)
a. Immersion scald burns
Immersion or spill /splash scald burnsusually by hot water. Can be accidental
or homicidal.
Accidental spill burns- usually children
involve. Usually the burns are on face,
neck, upper chest and arms. Clothing
protects the skin from spill scald burns.
c. Super heated steam/ hot air burns -
i. Skin- severe scald-like burns.
ii. With inhalation- of steam (moist hot gases)- burns of the
larynx, trachea, and alveolar occurs. Alveolar burns progress to
adult respiratory distress syndrome.
Some times can cause laryngeal oedema, leading to an
asphyxial death.
Super heated steam burns or hot air burns
2. Flame burns
3. Radiant heat burns
If low radiant heat• i. Usually 1st degree (erythema) or 2nd degree (blistering)
• ii. If prolonged exposure, the skin become light brown
leathery (= well done turkey)
• iii. if further exposure- can cause hair singing and even
charring of body.
If high radiant heat• 2nd degree burns even in 10 milliseconds
Radiant burns
Flash burns- type of radiant burns
Depth of burns
1) 1st degree
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Depth- Epithelium
Appearance- Erythema without blistering
(Histo- dilated congested vessels in dermis)
Epidermis is intact but there is some injury to the cells.
Later these cells can be peeled off as in sunburns.
Causes- Prolonged exposure to low intensity heat or light
(sun light) or short duration exposure to high intensity
heat or light
Pain(+)
Capillary return-(+)
Scarring- absent (Heals without scarring)
Eschar(-)
Muscle burns-(-)
2nd degree / partial thickness burns
 Depth-dermal
 Sub divided into Superficial or deep burns.
 2a.- Superficial partial thickness - Blustering stage. oedema at the dermo –
epidermal junction. Destruction of corneum, stiatum granulosum but the
basal epidermal layer not totally destroyed. Heals without scarring in 1/52.
2b- Deep partial thickness-Beyond the blister stage, but few blisters might be
found.
 complete disruption of dermis and destruction of most of the basal layer.
The dermal appendages (around hair, sebaceous and sweat glands are
spared. They can regenerate the epidermis. Therefore heals with or without
scarring in 2/52).
 Appearance 2a. blisters more.
 2b. beyond blister stage. Few blisters may be found. Moist, red lesions..
 Pain-(+)
 Capillary return-(+) Dermis appears red. Blotches on pressure.
 Scarring- Heals with or without scarring
 Eschar-(-)
 Muscle burns-(-)
3rd degree / full thickness burns
 Depth- Sub dermal/ sub cutaneous. Coagulation necrosis of the
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epidermis and dermis with destruction of all the dermal
appendages.
Appearance Usually dry, white, leathery lesions.
 Sometimes brown or black lesions due to charring and eschar
formation.
 No blisters
CausesPain- No
Capillary return- No
Scarring- Heals with scarring
Eschar-Can form an eschar, which is dry, hard and black. Later,
it sloughs off and underlying granulation tissue appears.
Muscle burns- No
4th degree burns/ deep burns
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Depth- Extending to subcutaneous tissue and beyond.
Appearance- charring
CausesPain-(-)
Capillary return-(-)
Scarring- Heals with scarring
Eschar-Can form an eschar, which is dry, hard and black.
Later, it sloughs off and underlying granulation tissue appears.
 Muscle burns-(+)
 Superficial muscles can get charred.
 Deep muscles can be partially cooked. (PM burning).
 If severe, pugilistic attitude (boxers posture)
 Candle effect- Subcutaneous tissue acts as wax. Clothes can
act as a wick. So, can burn the body as a candle
- 4th degree or deep burns - Pugilistic
attitude
Surface area of burns
It is measured according to the Walles’s rule of 9s. (Now
use Lund and Browder chart, especially for children.)
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Head- 9%
Upper limbs –9% each.
Trunk (front & back) – 18% each.
Lower limbs – 18% each.
Perineum – 1%.
(surface area of the palm is 1%. It can be used to assess the
incompletely burnt areas)
(9% x 3 + 18% x 4 + 1% = 100)
Rule of nine
Whether he was alive at the time of burn?
(Ante mortem or postmortem burns)
It is difficult to differentiate AM or PM burns by gross
examination. Even microscopic examination may not be
helpful if victim has not survived long enough to develop
an inflammatory reaction.
Blisters do not indicate AM or PM burns, as they can be
produced during PM period as well. Even the red rim
around blisters can be seen in PM blisters. Red margin can
be due to heat contraction of dermal capillaries forcing
blood to the periphery of the burn.
Injuries found on a burnt body other than burns?
1. Ante mortem injuries (i) Homicidal injuries,
(ii) AM Masonry falling
2. Postmortem injuries (i) Homicidal dismemberment of the body
(ii) PM masonry falling
(iii) PM burns (spurious wounds/heat artifacts) eg.
1. Heat rupture, 2. Heat fracture, 3. Heat haematoma
ii. Heat ruptures
Heat fractures – outer table
Pathophysiology of burns
1) Capillary dilatation and increased permeability
2)Blister formation (Therefore can develop hypovolaemic shock)
3)Absorption of oedema fluid (occur after about 2 days)
4) Sick cell syndrome (reduction of intra cellular potassium and increase
of intra cellular sodium)
5) Blood cells and muscles destruction (releasing potassium, calcium,
phosphate etc)
6) Acute renal failure (ischaemic acute renal tubular necrosis and toxic
acute renal tubular necrosis)
Cause of death in burns
Immediate deaths
a. Burns,
b. Smoke inhalation,
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(i) Hot gases – cause laryngeal oedema resulting asphyxia
(ii) Toxic gases – eg CO, CN, NO, Phosgene – cause poisoning.
(iii) Irrespirable gases – eg CO2 – cause hypoxia.
c. Masonry falling causing vital organ damage or traumatic asphyxia.
Delayed deaths
deaths within 2 - 3 days
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i. shock (including toxic shock),
ii. Fluid loss (hypovolaemic shock)
iii. Acute respiratory failure due to gas inhalation,
deaths after 2 - 3 days
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i. sepsis (following infected burns, bed sores, gas gangrene)
ii. Chronic respiratory failure,
iii. Renal failure – (ischaemic or toxic ARTN)
Causes of death in a body found in a burnt down house
1. Can die due to burns
Extensive burns
Gases
Masonry fallings
Lightning burns
High tension electrocution burns
2. Can die due to other causes
a) Homicidal (killed by other means and surreptitiously
disposed by PM burning)
b) Natural death – could have been aggravated by the effects of burn.
Aims of investigation of a burnt body
 1. Identification 2. If died of burns,
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Must be alive at the time of fire,
i. Swallowing of soot,
ii. Inhalation of soot and gases
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How did he die,
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i. Burns,
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ii. Smoke inhalation,
 3. If died of burns, why couldn’t he escapei. Suicide,
ii. Homicidal burns,
iii. Drunken or drugged,
iv. Disabled by acute or chronic illness,
 4. If didn’t die of burns, how did he die,
a. PM burning after killing by another method. Eg. manual or ligature
strangulation, stab, cuts, firearm injuries, head injuries etc.
b. Post crash fire in RTAs.
Smoke inhalation deaths
 Some bodies become severely burnt. But some show searing injury of skin
(become light brown colour with stiff leathery consistency) with or with out
blisters.
 Some times no burns at all. If no or minimal burns, the cause of death is
usually “smoke inhalation”.
 1. The commonest way is CO poisoning. If died of CO poisoning, diagnosis
is easy. Hypostasis, muscles and internal organs and blood are cherry-red
colour. But it is not enough, DDs – Cyanide poisoning, refrigeration.
Therefore blood CO level should be assessed. Some times, lethal CO level
may not have cherry red colour, hence blood level is very important. The
average CO level of deaths due to automobile exhaust gas is more than
70%. But in fire deaths, it is usually above 20%. Some times, can die even
at lower levels if other causes such as coronary atheroma also contribute.
 2. Oxygen deprivation
 3. Cyanide poisoning (but very rare in fire deaths. The other problem is the
interpretation of the blood level as it can enter blood by PM burning or
can produce even in the test tube due to decomposition. The other
problem is the false positives caused by sulfides in blood)
 4. Free radicals (inactivate surfactants thus prevent oxygen diffusion
through alveoli) ,
 5. Non-specified toxic substances.
Inhalation injuries By hot gases inhalation- whether it is dry or moist, can cause a rapidly fatal
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obstructive oedema of the larynx. But it is uncommon.
Laryngeal spasms can cause by extremely hot air inhalation. This concept is
how ever just conjecture.
Burning of the air passages.
a. Hot dry air inhalation- though it causes external skin burns, it has little
or no effect on the lower trachea or lungs. Dry air loose most of its heat before
reaching the lungs. Mild injury to upper trachea can occur.
b. Hot moist air inhalation (eg. steam inhalation)- burns of the airways
occur. Steam contains 4000 times more heat than dry air.
 Inhalation injuries of the lungs are chemical injuries caused by the by products
of incomplete combustion. They produce
 i. pulmonary oedema due to injury to endothelial –epithelial interface,
 ii. collapse of alveolar due to decreased production of surfactant,
 iii. Broncho-cilliary injury.
Causes of fire
1. Smoking – a common cause. Sleeping with
lighted cigarettes.
2. Children- due to lack of supervision. So the
parents can be charged for negligence. Social
services are also indirectly responsible.
7) Medico legal investigation of a burnt body
1. Authority – ISD or Magistrate order.
2. History –
History of the incident (from eye witnesses) – WWWWW
History after the incident (from eye witnesses) – dying declaration,
treatments given
History before the incident (from relatives) - PMH / PSH / social history
(alcohol, other abuses) / previous attempts of suicides, enemies, threats etc.
3. Visit to the scene
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Examine the surroundings
Place of killing or death - site of maximum burns
Site of the body found
Relationship between them.
Manner of death (NASH)- locked from inside etc.
Cause of death – preliminary idea
Trace evidence collection – weapons, inflammable substances, matches, soil beneath
the body for inflammable substances. etc.
Volitional activity – blood stains distribution, foot and palm prints, disturbance at the
scene
Then Examine the body
Attitude of the body – sexual posture, clothes raise etc
Injuries – compare with the surroundings
Cause of death – preliminary idea
Time since death – cooling by rectal temperature, rigor mortis, hypostasis,
putrefaction
Changing of position – eg raised hand indicates changing of position after
death.
Now cover the head and four extremities with cellophane bags and put the body into a
body bag and transport to the mortuary.
4. Identification of the deceased
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If no thermal injuries to body, the death is usually said to be caused by smoke inhalation. In
such bodies identification is not a problem. Visual identification, photographs and fingerprints
can be used.
But if facial structures are mutilated and no fingerprints can be obtained, other methods of
identification has to be used.
1. Dental identification. Therefore a PM dental chart is prepared and PM dental X-rays are
taken. Better if remove the jaws and can take good X-rays. Better if split at the middle and take
good lateral X-rays. Since these bodies are badly mutilated, should cause no problem with the
next of kin. Dental X-rays does not require fillings but can be made on bony structure of the
jaws and the orientation, structure and appearence of the teeth alone is enough for
identification. Even one tooth is enough for specific identification. Just as reliable as
fingerprinting.
2. Comparison of AM X-rays (skull, chest, abdomen, limb or any area is suitable) can be
compared with PM X-rays.eg. bone structures, soft tissue calcifications, gallstones, kidney
stones, clips, plates, screws etc. positive identification can be done even with single unique
finding.
3. DNA- if cannot identify by fingerprints, dental records, or X-rays, then DNA can be used.
(samples can be taken from deep thigh muscles, bone marrow or teeth)
4. If non of the above methods are available, can do only a tentative identification by using,
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i. circumstantial evidence,
ii. personal possession (documents, ornaments, cloths)
iii. tattoos, scars, absence of organs, deformities, defects, diseases etc.
 5. If no tentative identification is possible, can do facial reconstruction and publish in
media.
5. Preliminary investigations
Photographs with scale
X –rays – specially if firearm injury or bomb blast are
suspected
Trace evidence collection– if inflammable substance are used,
swabs from Clothes and body.
If sexual violence is suspected sperms swabs etc.
6. Clothing examination
Examine and remove the clothes. Air dry them and sent to
government analyst for inflammable substances analysis.
7. External examination
 1) Identification – as mentioned above
 2) Time since death assessment – may be difficult.
Rigor mortis - (difficult to interpret because with heating RM appear early and
disappear early. If completely charred body can be in heat stiffening [pugilistic attitude] )
Hypostasis - can be masked by skin burns. Sometimes hypostasis can be pink due to
CO poisoning.
Putrefaction – can be altered with secondary infections.
 3) Examination of Burns
 (i) Type – scald / dry / flash, (ii) Depth – 1st , 2nd , 3rd or 4th degree, (iii) SA – rule
of 9,
 (iv) Whether he was alive at the time of burn or not, (v) Clothing and hair burns
 4. Other injuries
 (i) Ante mortem injuries – homicidal (FAI, stab, blast etc), masonry falling
 (ii) Postmortem injuries – dismemberment, Masonry falling, Postmortem burns
(heat haematom heat rupture, heat fracture)
 5) Cause of death features
If immediate death - i. Burns, ii. Gases – (CO, CN, Phosgene poisoning, Asphyxial signs
due to laryngeal oedema, Hypoxic signs due to carbon dioxide poisoning.), iii. Masonary
fallings- traumatic asphyxia or vital organ damage
If delayed death – renal failure, Septicaemia, and Toxaemia features.
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Lab investigations
a) Blood for alcohol and toxicology
b)
Blood for gasses (CO, CN, Nitric Oxide and Phosgene)
c)
Histology for natural causes, septicaemia features (micro abscesses) etc.
Conclusions
(i)
Identification of victim (x ray, dental etc)
(ii)
Identification of weapon – if used
(iii)
Injuries interpretation – burn injuries / other injuries as discussed
above.
(iv)
Incident reconstruction – period of survival, volitional activity
(v)
Cause of death
(vi)
Category of hurt – especially in live patients
(vii)
Time since death – difficulties in assessment, as discussed above.
(viii)
Tests for sexual assaults – swabs for sperms (heat can destroy
seminal stains)
(ix)NASH (Natural / accidental/suicidal/homicidal/ postmortem
burning)
(x) Trace evidence collection- according to Locard’s principle.
Suicidal burns
 Rare.
 Douse themselves with a flammable liquid eg.Kerosene oil, and then set themselves on
fire.
 At the scene- flammable substance container, matches or cigarette lighter are usually
found. Examine them for fingerprints and compare them with the victim.
 On examinaton- 2 or 3rd degree burns most on the front side.
 Death- some times not immediate, but die of a complication. About 50% die at the scene.
 Investigations i. clothing to analyse volatile or petroleum substances. So they shoud be placed in a glass
container with a screw top cap. But not in plastic bags, a volatile substances can escape
through plastic.
 ii. soil beneath the body to analyse for volatile substances. Iii. Blood for CO- usually
elevated even they are flash fires. Some times can get a low (slightly elevated) or negative
CO level, if burnt at outdoors or in a larger room. But if suicide in a small enclosure such
a car, usually get an elevated CO.
 Relegious fanatics.
 Widows jump into creamating site.
Accidental burns
 Commonest is accidental burns. Kerosene burns.
 Kitchen burns.
 Industrial burns. (cracker factory burns)
 Incapacitated with alcohol or drugs and sleep with
lighted cigarettes.
 Lightning burns.
Homicidal burns
 1. Incendiary bombs (petrol bombs)
 2. Napam bombs
 3. Incapacitated with alcohol, drugs or head injury
and then set fire.
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Investigations has to be carried out by fire
experts also. Eg. government analyst.
 Reasons- i. for profit- insurance claims,
 ii. to take revenge,
 iii. pyromania,
 iv. to conceal a crime such as burglary.
Postmortem disposal by burning
 Reasons i. to conceal a homicide. Therefore the first thing the pathologist has to
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establish is that the individual is dead prior to fire.
How to suspect –
1. 4th degree burns , some times completely cremated. It is difficult to
completely cremate a body out side a crematorium due to high water
content. Unless the body was burnt on a grill like structure, so that as it
burns, the melting fat will feed the fire and contribute to the
consumption of the body. spontaneous human combusion is not
accepted now. so if highly cremated body, suspect postmortem burn
rather than an accidental fire.
2. Ante mortem injuries (firearm injuries, stabs, blast)
3. Inflammable substances
Chemical burns
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Tissue damage depends on,
i. agent,
ii. its concentration,
iii. quantity,
iv. duration of contact,
v. extent of penetration of the body.
chemicals continue to act on tissues until they are,
i. neutralized by another agent or
ii. inactivated by body tissues reactions
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ActionCoagulate proteins by,
i. reduction,
ii. oxidation,
iii. salt formation,
iv. corrosion,
v. protoplasmic poisoning,
vi. metabolic competition or inhibition,
vii. desiccation or
viii. ischaemic complication of vesicants.
Caused by,
i. acids,
ii. alkali,
iii. vesicants (blister producing substances)
iv. prolonged contact of some compounds- eg gasoline (partial
thickness burns) or cement.
Acids
 Strong acids- pH usually <2. They precipitate proteins. They cause coagulation
necrosis resulting hard eschar or scab. Burns are clearly demarcated, dry and
hard. Oedema is mild. Usually 2nd degree/ deep partial thickness burns. But if
prolonged contact, there can be 3rd degree burns eg. concentrated H2SO4 , HCl
or HNO3 . The scab usually dark, leather – like, dry. HCl causes much deeper
burns than others.
 Sulfuric acid- black or brown,
 Nitic acid – yellow scab,
 HCl- white or gray,
 Phenol – light gray or light brown,
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 Some acids cause not only skin burns but also systemic poisoning. Eg. phenol,
yellow phosphorous, ammonium sulfide.
 Eg.
i. Phenol associated with acute renal tubular necrosis,
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ii. phosphorus- liver and kidney necrosis.
Alkaline burns
 - need pH >11.5 to cause injury to tissues. Alkali’s cause
severe damage than acids as they dissolve proteins and
saponify fats. They cause liquefaction necrosis
resulting deeper invasion of tissues.
Microwave burns Mechanism – generate heat through molecular
agitation. Greater the water content, greater the
heat produced.
 Eg. skin and muscles has more water than fat in
subcutaneous tissue. Therefore sandwich type
burns. ie. Burns on skin and muscles but sparing
the in-between fat in subcutaneous tissue.
 Radiant heat of ovens cook from out side to in. but
microwaves directly heat the internal tissue. Direct
microwave injuries are rare. Eg accidental burns in
children or deliberate burns in children in battered
baby syndrome.
FlashFlash
fires
fires are the fires involving flammable hydrocarbon liquids. It
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starts with s flash and then follows with flame fire.
Flash occurs at flash point. Flash point is the temperature at which
sufficient fuel has evaporated to sustain a brief flash of fire.
Flame fire occurs at flame or fire point. Which is a slightly higher
temperature than the flash point. The initial flash will increase this
required temperature of the vapor for the flame to occur. Then it
continues to burn until it consumes the whole fuel. But flame will
not burn the fuel but the vapor that evaporate will be burnt until it
consume the whole fuel.
If flash fire occurs in a room,
In 45 seconds- oxygen falls and carbon dioxide increases markedly.
So in next 15 seconds CO produced. But if no new air enters to the
room, the fire will go out through lack of oxygen.
Flash
over Occur in fires in confined spaces eg. A room. After the
onset of the fire, even it is small, it causes radiant heat,
hot gases and smoke. Gases and smoke moves up and
form a layer immediately below the ceiling. Heat up the
ceiling and upper parts of the walls. With time the
thickness of this hot gases increases and extend
gradually down towards the floor. Then the radiant heat
from the fire and the heat of the gases heat up the lower
parts of the walls and objects on the floor. So the
combustible materials in the room begin to give off
flammable gases (this is called pyrolysis). At some point
the combustible objects reach their ignition
temperature. At this point the flame sweeps over the
room involving almost whole room at once. This is
called flash over. Usually it takes about 5-20 mts to start
the flash over. Usually the temperature at flash over is
500-600C.
Internal examination
 Compare with external injuries
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Exclude natural causes of death
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Find the real cause of death.
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 Organs examination
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No specific features will appear due to burns
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But some effects due to cause of death can manifest. Eg
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If immediate death – some times internal organs also burnt..
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asphyxia / gas poisoning/ hypoxic
features can appear.
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If delayed death – septicaemia features can appear.
 a)
Infected burns
 b)
Abscesses in most organs (if micro abscesses may not be seen to
naked eye)
 c)
Liver - fatty, large, yellow and friable
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Spleen – large, friable, diffluent
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Adrenal glands – haemorrhages
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Acute renal failure features can appear
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Kidneys swollen (cut section bulged out)
 b)
Cortex pale medulla congested.
Lab investigations
 a)
Blood for alcohol and toxicology
 b)
Blood for gasses (CO, CN, Nitric Oxide and
Phosgene)
 c)
Histology for natural causes, septicaemia
features (micro abscesses) etc.
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Conclusions
 (i) Identification of victim (x ray, dental etc)
 (ii) Identification of weapon – if used
 (iii) Injuries interpretation – burn injuries / other injuries as
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discussed above.
(iv) Incident reconstruction – period of survival, volitional
activity
(v) Cause of death
(vi) Category of hurt – especially in live patients
(vii) Time since death – difficulties in assessment, as discussed
above.
(viii) Tests for sexual assaults – swabs for sperms (heat can
destroy seminal stains)
(ix)NASH (Natural / accidental/suicidal/homicidal/ postmortem
burning)
(x) Trace evidence collection- according to Locard’s principle.
Thank you