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Forensic medicineForensic medicine

Classification of injuriesClassification of injuriesDr David ChumbaDr David Chumba

MBcHB, MMED (human MBcHB, MMED (human pathology), Dip. FOR Pathpathology), Dip. FOR Path

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OutlineOutlineTraumatology:Traumatology:– WoundsWounds– AsphyxiaAsphyxia– Thermal, electrical and radiation injuriesThermal, electrical and radiation injuries– Firearm and explosion injuriesFirearm and explosion injuries– Transportation injuriesTransportation injuries

Clinical forensic medicineClinical forensic medicine– Domestic violenceDomestic violence– Sexual offencesSexual offences– Medicolegal aspects of drugs and poisons including alcoholMedicolegal aspects of drugs and poisons including alcohol– Torture and custody related deathsTorture and custody related deaths

Forensic pathologyForensic pathology– Examination of the scene of deathExamination of the scene of death– AutopsyAutopsy– Death and post mortem changesDeath and post mortem changes– Sudden un expected deathsSudden un expected deaths– Human identificationHuman identification– Mass disastersMass disasters– Forensic odontologyForensic odontology

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Definitions: An injury is damage to the body Definitions: An injury is damage to the body caused by application of force (violence). A caused by application of force (violence). A wound occurs when the force applied to the wound occurs when the force applied to the body is greater than body’s ability to absorb body is greater than body’s ability to absorb safelysafelyInjury may be due to mechanical, chemical or Injury may be due to mechanical, chemical or physical factorsphysical factors

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Medicolegal classification of injuriesMedicolegal classification of injuries

Mechanical injuriesMechanical injuries– Bruise ( contusion )Bruise ( contusion )– Abrasion Abrasion – Wounds:Wounds:

Lacerated woundLacerated woundIncised woundIncised woundStab woundStab woundFire arm woundsFire arm wounds

– FracturesFractures

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Thermal injuriesThermal injuries::– Cold injuries include frost, trench foot and Cold injuries include frost, trench foot and

immersion footimmersion foot– Heat include burns and scalds Heat include burns and scalds

Injuries due to electricity, lightning, x-rays, Injuries due to electricity, lightning, x-rays, radio active substance etcradio active substance etcChemical injuriesChemical injuries– Corrosive acids Corrosive acids – Corrosive alkalisCorrosive alkalis

An injury due to a mechanical force is the result An injury due to a mechanical force is the result of an applied force evoking a counter force by of an applied force evoking a counter force by which energy is transferred to the body tissues, which energy is transferred to the body tissues, causing change in their state of rest or motion.causing change in their state of rest or motion.

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Excessive energy results in a wound. The nature and Excessive energy results in a wound. The nature and extent of the injuries depends on,extent of the injuries depends on,– Nature of object causing woundNature of object causing wound– Amount of energy dischargedAmount of energy discharged– Nature of affected tissueNature of affected tissue– Condition of the target hence a blunt injury to the scalp is Condition of the target hence a blunt injury to the scalp is

different from that which affects the stomachdifferent from that which affects the stomachDeterminants/factors that determine the nature and Determinants/factors that determine the nature and extend of wounds are mainly four factors:extend of wounds are mainly four factors:– Nature of instrument used: Sharp injury will result in small Nature of instrument used: Sharp injury will result in small

area focal point or a line, so depending on the amount of area focal point or a line, so depending on the amount of force the injury can be deep and penetrating to deeper force the injury can be deep and penetrating to deeper tissues. Blunt object will affects a relatively large area hence tissues. Blunt object will affects a relatively large area hence the damage is less e.g. the flat surface of a ruler causes less the damage is less e.g. the flat surface of a ruler causes less injury than the sharp edge. The consistency of the injury than the sharp edge. The consistency of the instrument e.g. Wood or stone and rubber ball will affect the instrument e.g. Wood or stone and rubber ball will affect the severity of the injuryseverity of the injury

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– The amount of energy discharged: This is known as kinetic The amount of energy discharged: This is known as kinetic energy and KE= 1/2mv^2 where m is the mass of the object energy and KE= 1/2mv^2 where m is the mass of the object in kilogram's, v is velocity in meters per second. This kinetic in kilogram's, v is velocity in meters per second. This kinetic energy is discharged at once when the object hit the body. If energy is discharged at once when the object hit the body. If the body is free and moves on impact reduces the amount of the body is free and moves on impact reduces the amount of energy dissipated. If the time it takes to release the energy is energy dissipated. If the time it takes to release the energy is increased, the destructive effects of the energy is reduced increased, the destructive effects of the energy is reduced e.g. catching a cricket ball with movement of the arm in the e.g. catching a cricket ball with movement of the arm in the same directionsame direction

– Nature of the affected tissue and shearing force: Skin is Nature of the affected tissue and shearing force: Skin is elastic and firm and strongly resistant to shearing forces elastic and firm and strongly resistant to shearing forces hence a blunt force may not damage the skin though severe hence a blunt force may not damage the skin though severe injury may be inflicted to the underlying tissues. injury may be inflicted to the underlying tissues. Subcutaneous connective tissue. This contain fat and Subcutaneous connective tissue. This contain fat and protects the body by its cushioning effect. Bones will fracture protects the body by its cushioning effect. Bones will fracture when the elasticity limit is reached due to it rigid structure. when the elasticity limit is reached due to it rigid structure. Body fluid are incompressible hence can cause rupture of Body fluid are incompressible hence can cause rupture of vessels at distant sitesvessels at distant sites

– Condition of the target e.g. presence of protective clothing, Condition of the target e.g. presence of protective clothing, thickness of the scalp, physique, age of the victim old and thickness of the scalp, physique, age of the victim old and fragile/young and healthyfragile/young and healthy

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Mechanical injuriesMechanical injuries

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AbrasionAbrasion

Is a blunt force injury that involve loss and Is a blunt force injury that involve loss and damage of the superficial epithelial layer of the damage of the superficial epithelial layer of the skin onlyskin onlyMay be caused by compression of superficial May be caused by compression of superficial layer of skin, or by friction against some rough or layer of skin, or by friction against some rough or sharp surface that scraps away the epidermissharp surface that scraps away the epidermisSince only epithelial layer involved, healing is Since only epithelial layer involved, healing is rapid and complete without scar formation rapid and complete without scar formation

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Types of abrasionTypes of abrasion

1.1. Scratch – refer to linear abrasions e.g by Scratch – refer to linear abrasions e.g by fingernail. A tag of skin seen at the end.fingernail. A tag of skin seen at the end.

2.2. Graze/brush – caused by lateral rubbing Graze/brush – caused by lateral rubbing movement. See heaps of skin tags at the end.movement. See heaps of skin tags at the end.

3.3. Friction abrasion – localised forces passing Friction abrasion – localised forces passing linearly over the skin e.g ligature mark in linearly over the skin e.g ligature mark in hanging or tramline abrasion of a whiphanging or tramline abrasion of a whip

4.4. Imprint/impact abrasion – caused by the skin Imprint/impact abrasion – caused by the skin being crushed by force perpendicular to skinbeing crushed by force perpendicular to skin

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Age of abrasionAge of abrasion Appearance DurationAppearance DurationBright red FreshBright red FreshScab formation 12 – 24 hrsScab formation 12 – 24 hrsScab is reddish brown 2 -3 daysScab is reddish brown 2 -3 daysEpithelium covers defect 4 – 7 daysEpithelium covers defect 4 – 7 daysFalling of scab After 7 daysFalling of scab After 7 daysMedicolegal aspects of abrasions: Medicolegal aspects of abrasions:

1. An abrasion indicates that a force has been applied at the site of injury1. An abrasion indicates that a force has been applied at the site of injury2. The direction of the applied force may be inferred from the way the epidermis is 2. The direction of the applied force may be inferred from the way the epidermis is grazedgrazed3. allow inferences to be drawn about the nature and shape of the object used3. allow inferences to be drawn about the nature and shape of the object used4. Aging of abrasion can determine the time of injury4. Aging of abrasion can determine the time of injury5. The type of asault can be inferrede from the type of abrasion e.g. finger nail 5. The type of asault can be inferrede from the type of abrasion e.g. finger nail abrasion on the neck indicate strangulationabrasion on the neck indicate strangulation6. Foreign material found at the site of injury may provide clues of the object used 6. Foreign material found at the site of injury may provide clues of the object used e.g. paint flakes or clothing fibrese.g. paint flakes or clothing fibres7. Post mortem lesions must be distinguished from ante mortem, the post mortem 7. Post mortem lesions must be distinguished from ante mortem, the post mortem are leathery, dry, irregular and found at moist skin foldsare leathery, dry, irregular and found at moist skin folds

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Bruises or contusionsBruises or contusionsIs a form of blunt injury in which there is extravasations of Is a form of blunt injury in which there is extravasations of blood into soft tissue spaces due to breaking of blood vessel blood into soft tissue spaces due to breaking of blood vessel walls. Results in discoloration of skin and soft tissues. No walls. Results in discoloration of skin and soft tissues. No discontinuity of skin.discontinuity of skin.The extent of bruising depends on amount of force applied to The extent of bruising depends on amount of force applied to the area and the type of tissue injuredthe area and the type of tissue injuredTypes of bruises:Types of bruises:

1.1. Impression- bruise reflects the type of object that caused itImpression- bruise reflects the type of object that caused it2.2. Peri-orbital hematoma (black eye) – bruises of and around Peri-orbital hematoma (black eye) – bruises of and around

the eyelid due to direct or indirect forcethe eyelid due to direct or indirect force3.3. Tramline – 2 parallel bruise lines caused by a longitudinal Tramline – 2 parallel bruise lines caused by a longitudinal

objectobject4.4. Bite marksBite marks5.5. Self-defense bruises – on the back of fingers, knuckles and Self-defense bruises – on the back of fingers, knuckles and

forearm/elbowsforearm/elbows6.6. IatrogenicIatrogenic

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Forensic/medicolegal importance of bruisingForensic/medicolegal importance of bruising– Generally they indicate blunt trauma but spontaneous hemorrhages Generally they indicate blunt trauma but spontaneous hemorrhages

must be ruled out, the presence of associated abrasions and lacerations must be ruled out, the presence of associated abrasions and lacerations indicate a traumatic etiology. The bruising may be pin point (petechie), indicate a traumatic etiology. The bruising may be pin point (petechie), medium sized (echymosis) or large referred to as hematomamedium sized (echymosis) or large referred to as hematoma

– The extent depend on age ie old people brusie more easily than young The extent depend on age ie old people brusie more easily than young people and women more than menpeople and women more than men

– Shape e.g. tram line indicates ruler, stick or sjambokShape e.g. tram line indicates ruler, stick or sjambok– The determination of age of bruises may indicate the time of injuryThe determination of age of bruises may indicate the time of injury– Careless dissection of the neck in case of hanging causes artefactual Careless dissection of the neck in case of hanging causes artefactual

bruising hence the need for a special procedure (bloodless neck bruising hence the need for a special procedure (bloodless neck dissection)dissection)

– antemortem brusing should not be confused with post mortem lividity or antemortem brusing should not be confused with post mortem lividity or hypostasis, histology is confirmatoryhypostasis, histology is confirmatory

– The site of the bruise may not be the site of injury as blood may move a The site of the bruise may not be the site of injury as blood may move a long facial planes e.g. Black eye may be seen fracture of the base of the long facial planes e.g. Black eye may be seen fracture of the base of the skullskull

– Contusion is synonymous with bruises but refers to internal organsContusion is synonymous with bruises but refers to internal organs

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Age of bruisesAge of bruises

Colour AgeColour AgeRed FreshRed FreshBlue Few hrs-3 daysBlue Few hrs-3 daysBlack-brown 4 daysBlack-brown 4 daysGreen-yellow 4 – 12 daysGreen-yellow 4 – 12 daysNormal 2 weeksNormal 2 weeks

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LacerationsLacerationsAre injuries that produce tearing of skin and subcutaneous tissues with Are injuries that produce tearing of skin and subcutaneous tissues with edges torn, jagged and irregular. Caused by blunt force, the tissues are edges torn, jagged and irregular. Caused by blunt force, the tissues are stretched to the point of tearing or splitting. It may be superficial or deepstretched to the point of tearing or splitting. It may be superficial or deepCharacteristic of lacerated wounds: Characteristic of lacerated wounds:

1.1. Wound margins are irregularWound margins are irregular2.2. Deeper tissues are also tornDeeper tissues are also torn3.3. May occur without any external woundMay occur without any external wound4.4. Shape of injury doesn`t correspond to the weapon usedShape of injury doesn`t correspond to the weapon used5.5. Bruises in the tissue around the woundBruises in the tissue around the wound6.6. Foreign bodies like sand, grass can be found in the woundForeign bodies like sand, grass can be found in the wound7.7. Chances of infection moreChances of infection more8.8. Tissue bridges within the woundTissue bridges within the wound

– Special types of lacerations. Scalp lacerations may appear like incised wounds Special types of lacerations. Scalp lacerations may appear like incised wounds only distinguished by above featuresonly distinguished by above features

– Stretch tears are special laceration caused by stretching the tissue e.g. skin Stretch tears are special laceration caused by stretching the tissue e.g. skin over the hipover the hip

– Degloving or avulsion injury may appear like peeling off of the skin with Degloving or avulsion injury may appear like peeling off of the skin with exposure of soft tissuesexposure of soft tissues

– Decollment injuries occur when the skin and subcutaneaous tissue move over Decollment injuries occur when the skin and subcutaneaous tissue move over each other, forming a cavity filled with blood and fatty tissue without overlying each other, forming a cavity filled with blood and fatty tissue without overlying skin being openskin being open

– Hook lacerationsHook lacerations

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Medicolegal importance of lacerations: Medicolegal importance of lacerations: This point to a blunt force traumaThis point to a blunt force trauma In the scalp lacerations may mimic incised woundsIn the scalp lacerations may mimic incised wounds Lacerations of the lip may be due to fall or a fist of an Lacerations of the lip may be due to fall or a fist of an

assailantassailant Wounds by sharp objectsWounds by sharp objects: Cause incised wounds : Cause incised wounds

with well defined edges – cutting or stabbing. with well defined edges – cutting or stabbing. Wounds may be linear, curved or V-shaped.Wounds may be linear, curved or V-shaped.

Characteristics of incised woundsCharacteristics of incised wounds1.1. Sharply outlined edgesSharply outlined edges2.2. Absence of abrasion or bruise around the woundAbsence of abrasion or bruise around the wound3.3. No bridging strands of tissueNo bridging strands of tissue4.4. No foreign materialNo foreign material5.5. Bleeds profuselyBleeds profusely6.6. No loss of hair around the woundNo loss of hair around the wound

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Medicolegal significance of incised wounds:Medicolegal significance of incised wounds: Incised or penetrating wound indicates sharp force traumaIncised or penetrating wound indicates sharp force trauma The site and appearance may indicate e.g. defense wounds The site and appearance may indicate e.g. defense wounds

suicide appear on the wrists, defense wounds on hands and suicide appear on the wrists, defense wounds on hands and forehandsforehands

Homicidal wounds are found on the chest, scalp, back, Homicidal wounds are found on the chest, scalp, back, abdomen while defense wounds are mainly found inside of the abdomen while defense wounds are mainly found inside of the palm, the fingers and the forearmpalm, the fingers and the forearm

In suicides the incisions are found on accessible areas neck, In suicides the incisions are found on accessible areas neck, wrists, antecubital surface, usually multiple with tentative pre wrists, antecubital surface, usually multiple with tentative pre incisions called hesitation cuts. The incisions are not made incisions called hesitation cuts. The incisions are not made through the clothing unlike in homicidethrough the clothing unlike in homicide

The surface size of an cut wound may not indicate the The surface size of an cut wound may not indicate the seriousness of the injury e.g. a prick by a bicycle spoke on the seriousness of the injury e.g. a prick by a bicycle spoke on the abdomen needs laparatomy as it may perforate small and abdomen needs laparatomy as it may perforate small and large gutlarge gut

Sarounding bruise indicates that the thrust was upto the hilt of Sarounding bruise indicates that the thrust was upto the hilt of the knifethe knife

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Complications associated with injury:Complications associated with injury:Local include:Local include:– Hemorrhage, primary, secondary or reactionaryHemorrhage, primary, secondary or reactionary– Infection. This may result in systemic infection seen as septicemai, pyemia. Gas Infection. This may result in systemic infection seen as septicemai, pyemia. Gas

gangrene and tetanus are well known complicationsgangrene and tetanus are well known complications

Systemic:Systemic:– Shock syndrome: This is a syndrome resulting from inadequate perfusion of the Shock syndrome: This is a syndrome resulting from inadequate perfusion of the

tissue leading to multiple tissue injury and later failure. It is classified as tissue leading to multiple tissue injury and later failure. It is classified as cardiogenic or hypovolemic shock. Loss of 10% (500 ml) is tolerated, while 10-cardiogenic or hypovolemic shock. Loss of 10% (500 ml) is tolerated, while 10-20% 500-100 ml can be tolerated if the compensatory mechanism is intact. 30% 20% 500-100 ml can be tolerated if the compensatory mechanism is intact. 30% causes peripheral circulatory failure and rapidly fatal. causes peripheral circulatory failure and rapidly fatal.

– Effects of shock. The effects of shock is mainly seen in the brain heart lungs and Effects of shock. The effects of shock is mainly seen in the brain heart lungs and kidneys. This is seen as ischeamic changes on areas of selective vulnarabilty kidneys. This is seen as ischeamic changes on areas of selective vulnarabilty e.g. purkinje fibres of cerebellum, Sommers sector of hippocampus and neurons e.g. purkinje fibres of cerebellum, Sommers sector of hippocampus and neurons of watershed areas (areas of brain between adjacent arterial blood supply).of watershed areas (areas of brain between adjacent arterial blood supply).

– The heart findings include subendocardial hemorrhage and necrosisThe heart findings include subendocardial hemorrhage and necrosis– The lungs show shock lung characterised by diffuse alveolar damage or ARDSThe lungs show shock lung characterised by diffuse alveolar damage or ARDS– The kidneys show acute tubular necrosisThe kidneys show acute tubular necrosis– The GIT show Cushings ulcers or mucosal hemorrhagesThe GIT show Cushings ulcers or mucosal hemorrhages– The adrenal show lipid depletion and liver shows centrilobular necrosis and fatty The adrenal show lipid depletion and liver shows centrilobular necrosis and fatty

degenerationdegeneration

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Embolism is defined as intravascular solid, air or liquid that is Embolism is defined as intravascular solid, air or liquid that is carried in the blood stream. Classified as:carried in the blood stream. Classified as:

Thrombo-embolism, most common and is a complication of injury. This Thrombo-embolism, most common and is a complication of injury. This clotting of blood in the blood vessels during life. Related to being clotting of blood in the blood vessels during life. Related to being immobilised, direct trauma to blood vessels. They can cause sudden immobilised, direct trauma to blood vessels. They can cause sudden death when saddle emboli or small pulmonary emboli causes death when saddle emboli or small pulmonary emboli causes pulmonary hypertensionpulmonary hypertension

Air embolism occurs if a large vessel is damaged as in the neck, or Air embolism occurs if a large vessel is damaged as in the neck, or iatrogeniciatrogenic

Amniotic fluid embolism: Due to prolonged labour or dificult labour Amniotic fluid embolism: Due to prolonged labour or dificult labour resulting pasage of amniotic fluid and its components into veins, and resulting pasage of amniotic fluid and its components into veins, and cause death by acusing anaphylaxis aor DICcause death by acusing anaphylaxis aor DIC

Fat embolism: Fat enter veins and transported to the lungs. This is Fat embolism: Fat enter veins and transported to the lungs. This is common after traumatic injury to bones, burns and non-traumatic common after traumatic injury to bones, burns and non-traumatic causes like pancreatitis, osteomyelitis and eclampsiacauses like pancreatitis, osteomyelitis and eclampsia

Foreign body embolism: Foreign bodies include pellets of drugs, Foreign body embolism: Foreign bodies include pellets of drugs, microbes like parasites etcmicrobes like parasites etc

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Regional injuries: Will not be covered read as Regional injuries: Will not be covered read as you had been taughtyou had been taught– HeadHead

Scalp injuries, fractures of the skull, contsions, Scalp injuries, fractures of the skull, contsions, diffuse brain injury, extradural, subdural, diffuse brain injury, extradural, subdural, subarachnoid and intracerebral hemorrhages. Brain subarachnoid and intracerebral hemorrhages. Brain swelling, features of raised intracranial pressure, swelling, features of raised intracranial pressure, hypoxic brain injuryhypoxic brain injury

– Abdominal injuriesAbdominal injuriesBlunt and penetrating injuriesBlunt and penetrating injuries

– Injuries to the limbsInjuries to the limbs– Thoracic injuriesThoracic injuries

Immediate life threatening injuries e.g. tension Immediate life threatening injuries e.g. tension pneumothorax, open pneumothorax, massive pneumothorax, open pneumothorax, massive hemothorax, flail chest including mechanism of death hemothorax, flail chest including mechanism of death in chest injuriesin chest injuries

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Asphyxia:This is defined as interference with Asphyxia:This is defined as interference with respiration or interference with ability to breath.This respiration or interference with ability to breath.This definition includes all modes of death including anoxia definition includes all modes of death including anoxia resulting from any cause. The better definition should resulting from any cause. The better definition should therefore include the cause of anoxia e.g. chocking, therefore include the cause of anoxia e.g. chocking, strangulation, or carbon monoxide poisoningstrangulation, or carbon monoxide poisoningClassical signs of asphyxia:Classical signs of asphyxia:– Cyanosis: This occurs after 5 g of reduced hemoglobin per Cyanosis: This occurs after 5 g of reduced hemoglobin per

100 ml of blood irrespective of the total amount of blood100 ml of blood irrespective of the total amount of blood– Petechial hemorrhages, arising in the skin, the sclera, Petechial hemorrhages, arising in the skin, the sclera,

conjunctiva and serous membranesconjunctiva and serous membranes– Visceral congestion, this is due to decreased venous return Visceral congestion, this is due to decreased venous return

and may lead to edema and hypoxia leading to increased and may lead to edema and hypoxia leading to increased permeabilitypermeability

– Post-mortem fluidity is due to fibrinolysis after as part of Post-mortem fluidity is due to fibrinolysis after as part of decompensation processdecompensation process

– Right sided cardiac dilatation is non specific finding in people Right sided cardiac dilatation is non specific finding in people dying of asphyxiadying of asphyxia

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Mechanism of death in asphyxia: There are six Mechanism of death in asphyxia: There are six possible mechanisms of death in mechanical possible mechanisms of death in mechanical asphyxia:asphyxia:– Airway occlusionAirway occlusion– Occlusion of neck veins will lead to reduced blood to the Occlusion of neck veins will lead to reduced blood to the

right side of the heart and manifests as facial congestion and right side of the heart and manifests as facial congestion and petechial hemorrhagespetechial hemorrhages

– Occlusion of neck arteries: This is more difficult and rareOcclusion of neck arteries: This is more difficult and rare– Neural effect: The pressure on the baroreceptors in th Neural effect: The pressure on the baroreceptors in th

carotid sinus will lead to reflex bradycardia or asystolecarotid sinus will lead to reflex bradycardia or asystole– Cervical spine injury: Usually damage to the brain stemCervical spine injury: Usually damage to the brain stem– Combined mechanism: Combined mechanism: Classification of asphyxia: Divided into three broad Classification of asphyxia: Divided into three broad categories:categories:– Environmental: High altitudeEnvironmental: High altitude– Mechanical e.g. obstruction of the airwayMechanical e.g. obstruction of the airway– Toxic. This is replacement og oxyhemoglobin by carbon Toxic. This is replacement og oxyhemoglobin by carbon

monoxide, depression of the CNS by alcohol or narcotics monoxide, depression of the CNS by alcohol or narcotics and interference by cytochrome oxidase by cyanideand interference by cytochrome oxidase by cyanide

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Mechanical asphyxia:Mechanical asphyxia:

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Types of asphyxia: Types of asphyxia: – Vitiated atmosphere, this refers to high altitude, lack of oxygen in a Vitiated atmosphere, this refers to high altitude, lack of oxygen in a

closed truck etcclosed truck etc– Smothering: The refers to external blockage of the air ways by hands, Smothering: The refers to external blockage of the air ways by hands,

pillows, plastic bags etcpillows, plastic bags etc– Chocking: This refers to blockage of internal air passages by foreign Chocking: This refers to blockage of internal air passages by foreign

objects such as food, dentures etcobjects such as food, dentures etc– Manual strangulation (throttling): This refers to application of force Manual strangulation (throttling): This refers to application of force

usually by hands or forearm on the neckusually by hands or forearm on the neck– Ligature strangulation: This refers to the use of a rope cord or wire to Ligature strangulation: This refers to the use of a rope cord or wire to

constrict the neckconstrict the neck– Hanging: constriction of the neck by a ligature in which it is tightened by Hanging: constriction of the neck by a ligature in which it is tightened by

down ward pull of the bodies massdown ward pull of the bodies mass– Sexual asphyxia: This refers to deprivation of oxygen to heighten sexual Sexual asphyxia: This refers to deprivation of oxygen to heighten sexual

gratification during masturbation by use of ligature, or plastic bag, gratification during masturbation by use of ligature, or plastic bag, although it looks like suicide, this deaths are accidentalalthough it looks like suicide, this deaths are accidental

– Traumatic asphyxia: This refers to fixation of the chest by a heavy object Traumatic asphyxia: This refers to fixation of the chest by a heavy object eg. Sand, car atc which restrict breathingeg. Sand, car atc which restrict breathing

– Drowning: Deaths that occur as a result of partial or complete immersion Drowning: Deaths that occur as a result of partial or complete immersion of the body in water or another liquid of the body in water or another liquid

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Drowning: 85%-95% die of water inhalation referred to as wet Drowning: 85%-95% die of water inhalation referred to as wet drowning. The mechanism is inhalation of water resulting in drowning. The mechanism is inhalation of water resulting in respiratory tract inhalation, hypoxia due to interference of the respiratory tract inhalation, hypoxia due to interference of the alveolar-capillary air-blood interfacealveolar-capillary air-blood interfaceThe other 5-15% get a reflex laryngeal spasms due to The other 5-15% get a reflex laryngeal spasms due to unexpected entry of water into the larynxunexpected entry of water into the larynxAutopsy findings after drowning: They are not specific hence it Autopsy findings after drowning: They are not specific hence it considered as one of exclusion. Suggestive features include:considered as one of exclusion. Suggestive features include:– Post mortem lividity is usually marked on the face, head and neck, this is Post mortem lividity is usually marked on the face, head and neck, this is

because bodies immersed in water will float head downbecause bodies immersed in water will float head down– Cutis anserina or goose flesh is spasms of erector pilae musclesCutis anserina or goose flesh is spasms of erector pilae muscles– Whitening and wrinkling of the skin referred to as washer woman Whitening and wrinkling of the skin referred to as washer woman

appearanceappearance– Peeling of the epidermis is seen in prolonged immersion in waterPeeling of the epidermis is seen in prolonged immersion in water– Mastoid air cell hemorrhages are seen as bleeding form the earsMastoid air cell hemorrhages are seen as bleeding form the ears

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Thermal, electrical and radiation injuries:Thermal, electrical and radiation injuries:Burns: classification is based on type or cause e.g. flame, Burns: classification is based on type or cause e.g. flame, contact, chemical, electrical, radiation and inhalationcontact, chemical, electrical, radiation and inhalationAlso classified based on severity of burns: first degree limited to Also classified based on severity of burns: first degree limited to the epidermis, second degree invoves all the epidermis and the epidermis, second degree invoves all the epidermis and part of the dermis, third degree and fourth degree (where there part of the dermis, third degree and fourth degree (where there is charring of the body)is charring of the body)Factors influencing the severity of burns: This include the Factors influencing the severity of burns: This include the surface area affected, cause and intensity of the heat source, surface area affected, cause and intensity of the heat source, the duration of the exposure, site of the burn, age of the victim the duration of the exposure, site of the burn, age of the victim (y and elderly) and prior physical condition or concomitant (y and elderly) and prior physical condition or concomitant injuriesinjuriesIdentification of charred bodies: This is based on the Identification of charred bodies: This is based on the radiological studies prosthesis artificial hip, pace maker etc, radiological studies prosthesis artificial hip, pace maker etc, teeth antemortem records of dental work can be compared with teeth antemortem records of dental work can be compared with post mortem, stigmata e.g. congenital abnormalities, scars, post mortem, stigmata e.g. congenital abnormalities, scars, absent organs, prosthesis, clothing fragments of clothing are absent organs, prosthesis, clothing fragments of clothing are found under the arm pits or hidden areas, finger prints and found under the arm pits or hidden areas, finger prints and intrenal viscera e.g. the presence of prostate or uterusintrenal viscera e.g. the presence of prostate or uterus

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Determination of whether dead or alive at the time of Determination of whether dead or alive at the time of firefire– Carbon monoxide level should be measured the upper limit Carbon monoxide level should be measured the upper limit

of normal is 10% values greater than 10% person indicate of normal is 10% values greater than 10% person indicate that the person was alive at the time of the firethat the person was alive at the time of the fire

– The presence of smoke ash, soot, or other products of The presence of smoke ash, soot, or other products of combustion in the air ways lungs etc combustion in the air ways lungs etc

– Demonstration of pulmonary fat embolism indicates the Demonstration of pulmonary fat embolism indicates the circulation was intact during the burnscirculation was intact during the burns

Electrical injuries: The cause of death are mainly four:Electrical injuries: The cause of death are mainly four:– Ventricular fibrillation due to passage of current through the Ventricular fibrillation due to passage of current through the

heart muscleheart muscle– Respiratory muscle paralysis due to spasms of the Respiratory muscle paralysis due to spasms of the

diaphragm and costal musclesdiaphragm and costal muscles– Brainstem paralysis causing respiratory failureBrainstem paralysis causing respiratory failure– Associated injuries such as thermal injuriesAssociated injuries such as thermal injuries

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The firearm discharge residue consist of the following:The firearm discharge residue consist of the following:– Primer which contains lead, antimony and bariumPrimer which contains lead, antimony and barium– Powder consisting of nitrocellulose, nitroglycerine (grease Powder consisting of nitrocellulose, nitroglycerine (grease

wipe)wipe)– Projectile which is made of lead, copper and ironProjectile which is made of lead, copper and iron– Cartridge made of copper, zinc, nickelCartridge made of copper, zinc, nickel– Barrel made of iron and oilBarrel made of iron and oil

Firearm injuries: Types of fire armsFirearm injuries: Types of fire arms– Rifled firearmsRifled firearms

Hand guns e.g. pistols and rivolversHand guns e.g. pistols and rivolversHigh velocity riffle e.g. R1, R4/5 and AK47High velocity riffle e.g. R1, R4/5 and AK47

– Smooth bore firearms (short guns)Smooth bore firearms (short guns)– Home made fire armsHome made fire arms– Fire arms that fire rubber bullets and plastic bullets, tear gasFire arms that fire rubber bullets and plastic bullets, tear gas– explosivesexplosives