Wounds from Forensic Prospect

Almumtin, Ahmed Taher, MD

Role of the PathologistRole of the Pathologist

• Determine type of woundDetermine type of wound

• Measure the dimensions (length, width, depth)Measure the dimensions (length, width, depth)

• Position relative to anatomical landmarksPosition relative to anatomical landmarks

• Determine initial location if wound involves cutting, Determine initial location if wound involves cutting, slashing, etc.slashing, etc.

• Determine height of victim, other contributing factors Determine height of victim, other contributing factors like heart problems.like heart problems.

Analysis of WoundsAnalysis of Wounds

• Not every crime victim is murdered. Not every crime victim is murdered.

• Pathologists can contribute to proof of the severity of a Pathologists can contribute to proof of the severity of a crime or that a crime actually occurred in some cases for crime or that a crime actually occurred in some cases for a living victim.a living victim.

• Some victims are too young to testify and some are too Some victims are too young to testify and some are too severely injured to remember the crime. severely injured to remember the crime.

• Wounds provide evidence of the crime.Wounds provide evidence of the crime.

Wound CategoriesWound Categories

• Bruises (or contusions) Bruises (or contusions)

• Abrasions (or grazes or scratches) Abrasions (or grazes or scratches)

• Lacerations Lacerations

• Incised wounds Incised wounds

• Puncture (or stab) wounds Puncture (or stab) wounds

• Gunshot woundsGunshot wounds

Gunshot WoundsGunshot WoundsThis will be discussed with ballistics talkThis will be discussed with ballistics talk

Gunshot WoundsGunshot Wounds

Starring of a contact wound – barrel touching the skin

Stippling – powder burns on the skin when the gun is inches to a few feet from the victim

Gunshot woundsGunshot wounds

Contact Wound:Contact Wound: Muzzle Muzzle applied to skin at shooting.applied to skin at shooting.

Impression of muzzle burned Impression of muzzle burned around entrance wound around entrance wound

Close Range (6-8 inches): Close Range (6-8 inches): SStipplingtippling

Intermediate Range (1- 3 ft.):Intermediate Range (1- 3 ft.): hot fragments of burning hot fragments of burning gunpowder; gunpowder; ““ballball””

Distant (greater than 3 ft.): Distant (greater than 3 ft.): No No soot or burning of wound marginssoot or burning of wound margins

Entrance wound: surrounding Entrance wound: surrounding skin dragged in skin dragged in

Exit wound: skin pushed outExit wound: skin pushed out

Close rangeClose range

• Close RangeClose Range

• (6-8 inches): (6-8 inches): Entrance Entrance surrounded by surrounded by stipplingstippling- - HOT soot traveling for short HOT soot traveling for short distance; BURNSdistance; BURNS

Intermediate rangeIntermediate range

• Intermediate rangeIntermediate range

• 1-3 feet1-3 feet

• Gunpowder Gunpowder ““ballball””

Bruises Bruises

• A bruise is "a hemorrhage into tissues produced by the escape A bruise is "a hemorrhage into tissues produced by the escape of blood from blood vessels". of blood from blood vessels".

• Bruises may be found in the skin, muscles, and internal organs. Bruises may be found in the skin, muscles, and internal organs.

BruisesBruises

• Bruises are typically produced by a blunt force impact, Bruises are typically produced by a blunt force impact, such as a blow or a fall.such as a blow or a fall.

• They may also be produced by squeezing or pinching, They may also be produced by squeezing or pinching, where the force is applied gradually and then maintained. where the force is applied gradually and then maintained.

• Hickies or "love-bites" are superficial bruises. Hickies or "love-bites" are superficial bruises.

Natural BruisesNatural Bruises

• Bruises may occur in a variety of natural diseases Bruises may occur in a variety of natural diseases in which there is an abnormality of the clotting in which there is an abnormality of the clotting mechanism of the blood, e.g. scurvy (vitamin C mechanism of the blood, e.g. scurvy (vitamin C deficiency), leukemia, alcoholic liver disease. deficiency), leukemia, alcoholic liver disease.

• This bruising is "spontaneous" because the injury This bruising is "spontaneous" because the injury which produces it is so insignificant as to which produces it is so insignificant as to typically pass unnoticed. typically pass unnoticed.

• The presence of such natural disease will The presence of such natural disease will exaggerate the bruising effects of any trauma.exaggerate the bruising effects of any trauma.

Problems with Skin BruisesProblems with Skin Bruises

• Delayed appearance Delayed appearance

• Ageing (relative) Ageing (relative)

• Site of Trauma Site of Trauma

• Shape of object Shape of object

• Degree of force Degree of force

• Post-mortem bruises Post-mortem bruises

• Post-mortem lividityPost-mortem lividity

Classic Causes of BruisesClassic Causes of Bruises

• Finger pad bruises: battered babies, manual strangulation Finger pad bruises: battered babies, manual strangulation

• Different ages: repeated assaults Different ages: repeated assaults

• Shoulders and arms: forceful restraint Shoulders and arms: forceful restraint

• Wrists and ankles: dragging Wrists and ankles: dragging

• Inner thighs: forceful intercourse Inner thighs: forceful intercourse

• Chest: resuscitationChest: resuscitation

• Bruising is uncommon in SuicidesBruising is uncommon in Suicides

BruisesBruises

• The extent of bruising is inversely proportional to The extent of bruising is inversely proportional to the sharpness of the impacting object.the sharpness of the impacting object.

• Bruises may be associated with other blunt force Bruises may be associated with other blunt force injuries such as abrasions and lacerations. injuries such as abrasions and lacerations.

• As a general rule bruising is not associated with As a general rule bruising is not associated with incised wounds or stab wounds where there is a incised wounds or stab wounds where there is a free flow of blood from the cut blood vessels free flow of blood from the cut blood vessels rather than leaking into the tissues.rather than leaking into the tissues.

Site of TraumaSite of Trauma

• In contrast with abrasions, the location of a bruise does not In contrast with abrasions, the location of a bruise does not necessarily reflect the precise point of injury. necessarily reflect the precise point of injury.

• Leaking blood will follow the path of least resistance and Leaking blood will follow the path of least resistance and gravity. gravity.

Delayed AppearanceDelayed Appearance

• Deep bruises may have delayed appearance at the skin Deep bruises may have delayed appearance at the skin surface. Deep bruises may require as long as 12 or 24 surface. Deep bruises may require as long as 12 or 24 hours to become apparent, and some may never do sohours to become apparent, and some may never do so

• The more superficial the source of bleeding, the The more superficial the source of bleeding, the sooner the discoloration will be seen on the skin sooner the discoloration will be seen on the skin surface. surface.

• In a living victim, a second examination in one or two In a living victim, a second examination in one or two days may show bruising. days may show bruising.

• In the dead, a further examination one or two days In the dead, a further examination one or two days after the original autopsy may show bruises which after the original autopsy may show bruises which were not previously seen and reveal previously faint were not previously seen and reveal previously faint bruises.bruises.

Autopsy and BruisingAutopsy and Bruising

Bruising in Deep TissueBruising in Deep Tissue

1. Possibly life-threatening1. Possibly life-threatening

2. Sometimes no external injury2. Sometimes no external injury

3. Revealed in autopsy3. Revealed in autopsy

Documenting BruisingDocumenting Bruising

1.1. PhotographyPhotography

2. Notes2. Notes

Degree of ForceDegree of Force

• The size of a bruise is an unreliable indicator of the The size of a bruise is an unreliable indicator of the degree of force causing it. degree of force causing it.

• However, a heavy impact is likely to produce a large However, a heavy impact is likely to produce a large bruise and a light impact to produce a small bruise. bruise and a light impact to produce a small bruise.

• If bruising is slight, it is reasonable to assume that the If bruising is slight, it is reasonable to assume that the degree of violence was slight. degree of violence was slight.

Determining Degree of Force in Determining Degree of Force in Bruise PatternsBruise Patterns

Location:Location:

• Some areas of the body bruise more easily than Some areas of the body bruise more easily than others. The face bruises more readily than the hands. others. The face bruises more readily than the hands.

• Bruising occurs more readily in loose tissues and Bruising occurs more readily in loose tissues and where there is a large amount of subcutaneous fatwhere there is a large amount of subcutaneous fat

• Bruising is less apparent where the skin is strongly Bruising is less apparent where the skin is strongly supported by fibrous tissue or if the muscle tone is supported by fibrous tissue or if the muscle tone is good.good.

Determining Degree of Force in Determining Degree of Force in Bruise PatternsBruise Patterns

• AgeAge• Infants and the elderly tend to bruise more easily than young and Infants and the elderly tend to bruise more easily than young and

middle aged adults.middle aged adults.• Infants have loose and delicate skin, and the abundant subcutaneous Infants have loose and delicate skin, and the abundant subcutaneous

fat.fat.• Elderly have degenerative changes in the tissues which support the Elderly have degenerative changes in the tissues which support the

small blood vessels of the skin and subcutaneous tissues.small blood vessels of the skin and subcutaneous tissues.

• Gender:Gender:• Women bruise more easily than men because they have more Women bruise more easily than men because they have more

subcutaneous fat and this is particularly true of obese women.subcutaneous fat and this is particularly true of obese women.

• Natural DiseaseNatural Disease

• Skin color Skin color

Causitive ObjectCausitive Object

• The shape of the bruise is most likely to reflect the shape The shape of the bruise is most likely to reflect the shape of the causative object when the object is small and hard of the causative object when the object is small and hard and death occurs soon after injuryand death occurs soon after injury

Causitive ObjectCausitive Object

• A doughnut bruise is produced by an object with a A doughnut bruise is produced by an object with a rounded contour (e.g. baseball). rounded contour (e.g. baseball).

• Two parallel linear bruises result from a blow with a rod Two parallel linear bruises result from a blow with a rod or stickor stick

• Bruises can follow rounded contours if they are caused by Bruises can follow rounded contours if they are caused by a flexible object like a lasha flexible object like a lash

Causitive ObjectCausitive Object

• Bruises produced by fingerpads as a result of gripping are Bruises produced by fingerpads as a result of gripping are usually larger than the fingerpads themselves.usually larger than the fingerpads themselves.

• The pattern and location suggests the mechanism of causation:The pattern and location suggests the mechanism of causation:• On the neck in throttlingOn the neck in throttling

• On the upper arms in restraint.On the upper arms in restraint.

• Such bruises are referred to as patterned.Such bruises are referred to as patterned.

Aging of BruisesAging of Bruises•Color changes a bruise goes through can give a rough estimate of time of injury•Colors result from breakdown of hemoglobin from tissues

•Dark blue/purple (1-18 hours)

•Blue/brown (~1 to 2days)

•Green (~ 2 to 3 days)

•Yellow (~3 to 7 days)

•This rate assumes person is healthy, however.

Aging BruisesAging Bruises

• While accurate estimation of the age of a single While accurate estimation of the age of a single bruise is not possible, a fresh bruise can be bruise is not possible, a fresh bruise can be distinguished easily from one which is several distinguished easily from one which is several days old. days old.

• Establishing that bruises are of different ages may Establishing that bruises are of different ages may be of medical importance where there is an be of medical importance where there is an allegation of repeated assaults:allegation of repeated assaults:• Child abuse Child abuse • Wife beatingWife beating• Where pre-existing injuries need to be distinguished Where pre-existing injuries need to be distinguished

from those produced by a recent assault like a chronic from those produced by a recent assault like a chronic alcoholic who was assaulted. alcoholic who was assaulted.

Post MortemPost Mortem Bruises Bruises

• Bruising is a phenomenon of living tissue- since it usually Bruising is a phenomenon of living tissue- since it usually requires circulating blood to push the blood from the requires circulating blood to push the blood from the veins.veins.

• It isnIt isn’’t possible to tell bruises that occurred causing death t possible to tell bruises that occurred causing death from those that occurred minutes earlier. You can only from those that occurred minutes earlier. You can only say they occurred at or about time of death.say they occurred at or about time of death.

Post MortemPost Mortem Bruises Bruises

• It requires considerable violence to produce a bruise It requires considerable violence to produce a bruise post mortempost mortem or after death. or after death.

• These bruises are smaller relative to the degree of These bruises are smaller relative to the degree of force used. force used.

• Post mortemPost mortem bruises are most readily produced in bruises are most readily produced in areas of hypostasis (post mortem lividity, areas of hypostasis (post mortem lividity, livor mortislivor mortis) ) or where tissues can be forcibly compressed against or where tissues can be forcibly compressed against bone.bone.

• A bruise can develop on the head after the body is left A bruise can develop on the head after the body is left lying on the back.lying on the back.

Post Mortem Lividity (hypostasis, Post Mortem Lividity (hypostasis, livor mortislivor mortis))

• The settling, after death, of blood within the blood The settling, after death, of blood within the blood vessels under the influence of gravity. vessels under the influence of gravity.

• This results in a purplish discoloration of parts of the This results in a purplish discoloration of parts of the body that are lower while sparing areas of pressure body that are lower while sparing areas of pressure contact - contact pallor. contact - contact pallor.

• The pattern and distribution of lividity distinguishes it The pattern and distribution of lividity distinguishes it from bruising.from bruising.

• A body found on its back has A body found on its back has livor mortislivor mortis on the on the dorsal (back) side with pale areas where the bone dorsal (back) side with pale areas where the bone contacted the floor.contacted the floor.

DecompositionDecomposition

• Post mortem decomposition with its initial green Post mortem decomposition with its initial green discoloration of the anterior abdominal wall is readily discoloration of the anterior abdominal wall is readily distinguished from bruising. distinguished from bruising.

• Putrefactive lysis of blood cells within the vessels Putrefactive lysis of blood cells within the vessels and decompositional breakdown of the vessel walls and decompositional breakdown of the vessel walls results in diffusion of lysed blood into the adjacent results in diffusion of lysed blood into the adjacent tissues.tissues.

• Existing bruises are enlarged by this process.Existing bruises are enlarged by this process.

• Later, putrefactive hemolytic staining of tissue may Later, putrefactive hemolytic staining of tissue may mask mask ante mortemante mortem bruising (e.g. in the neck muscles bruising (e.g. in the neck muscles in case of choking).in case of choking).

Patterns of InjuryPatterns of Injury

• Bruises to the knuckles of the hands, together with Bruises to the knuckles of the hands, together with bruises of the eyelids, bridge of the nose, cheeks and bruises of the eyelids, bridge of the nose, cheeks and lips, suggest a fist fight.lips, suggest a fist fight.

• Bruising around the eyes (spectacle bruises) may be Bruising around the eyes (spectacle bruises) may be produced by direct blows, but also commonly result produced by direct blows, but also commonly result from a fracture of the base of the skull, e.g. in vehicle from a fracture of the base of the skull, e.g. in vehicle collisions or gunshot wounds to the head collisions or gunshot wounds to the head

• They may also follow blunt impact to the forehead They may also follow blunt impact to the forehead producing jolting of the eyeballs in their sockets with producing jolting of the eyeballs in their sockets with tearing of small orbital blood vessels.tearing of small orbital blood vessels.

Patterns of InjuryPatterns of Injury

• Bruising of the genitalia and around the anus suggests Bruising of the genitalia and around the anus suggests sexual assault. sexual assault.

• Severe bruising of the genitalia, with or without Severe bruising of the genitalia, with or without laceration, can be produced by kicks.laceration, can be produced by kicks.

• Counter-pressure bruising, with or without abrasion, Counter-pressure bruising, with or without abrasion, to the back, (shoulder blades, sacrum and pelvis) to the back, (shoulder blades, sacrum and pelvis) suggests pressure against a firm surface as in forceful suggests pressure against a firm surface as in forceful restraint on the ground.restraint on the ground.

• Similar bruising may be seen on boney prominences Similar bruising may be seen on boney prominences of the front of the pelvis.of the front of the pelvis.

Patterns of InjuryPatterns of Injury

• In kicking assaults with the shod foot, bruises are In kicking assaults with the shod foot, bruises are invariably associated with multiple abrasions and invariably associated with multiple abrasions and lacerations. lacerations.

• Gangs, individuals without weaponsGangs, individuals without weapons

• The bruises and abrasions may be patterned by the The bruises and abrasions may be patterned by the boot. boot.

• Bruising is typically extensive and targeted on the Bruising is typically extensive and targeted on the face, neck, ears, groin, and kidney area. face, neck, ears, groin, and kidney area.

• Internal bruising is usually severe.Internal bruising is usually severe.

Patterns of InjuryPatterns of Injury

• Bruises are painful and therefore not commonly self-Bruises are painful and therefore not commonly self-inflicted; extensive bruising creates a presumption of inflicted; extensive bruising creates a presumption of assault. assault.

• Accidents generally are unforeseen and the injuries they Accidents generally are unforeseen and the injuries they produce tend not to follow a recognizable pattern.produce tend not to follow a recognizable pattern.

• Some places bruise easily accidentally though: shins and Some places bruise easily accidentally though: shins and hips.hips.

Patterns of InjuryPatterns of Injury

• Injuries in motor vehicle collisions almost invariably Injuries in motor vehicle collisions almost invariably include abrasions and lacerations as well as bruises.include abrasions and lacerations as well as bruises.

• Patterns of injury may allow reconstruction of incidents Patterns of injury may allow reconstruction of incidents involving pedestrians or allow distinction between driver involving pedestrians or allow distinction between driver and front seat passenger.and front seat passenger.

Participation QuestionParticipation Question

• Give me an example of forensic usefulness of analysis of Give me an example of forensic usefulness of analysis of bruises.bruises.

AbrasionsAbrasions•Friction injury removing skin or tissue

AbrasionsAbrasions

• Side impact produces a moving abrasion:Side impact produces a moving abrasion:• Indicates direction. Indicates direction. • Trace material (e.g. grit).Trace material (e.g. grit).

• Direct impact produces an imprint abrasion:Direct impact produces an imprint abrasion:• Pattern of causative object.Pattern of causative object.

• All abrasions reflect site of impact (in contrast with All abrasions reflect site of impact (in contrast with bruises).bruises).

• Assessment of age of abrasions is difficult.Assessment of age of abrasions is difficult.

• Post-mortem abrasions - Brown, leatheryPost-mortem abrasions - Brown, leathery

Incised Wounds (Cuts, Slashes, Incised Wounds (Cuts, Slashes, Stab)Stab)

• Stab wounds or puncture wounds are penetrating injuries Stab wounds or puncture wounds are penetrating injuries whose depth within the body is much greater than the whose depth within the body is much greater than the dimensions of the wound on the body surface. dimensions of the wound on the body surface.

• Breach of the full thickness of the skin due to contact Breach of the full thickness of the skin due to contact with a sharp edge.with a sharp edge.

Stab WoundsStab Wounds

• Forensic ImportanceForensic Importance • Reflects sharp edge, not weapon type Reflects sharp edge, not weapon type • No trace evidence No trace evidence • Bleeds profusely Bleeds profusely • Hemorrhage and air embolismHemorrhage and air embolism

• They can be produced by any long thin object They can be produced by any long thin object which impacts the body with sufficient force to which impacts the body with sufficient force to penetrate. penetrate.

• The typical instrument is a knife, but any sharp The typical instrument is a knife, but any sharp pointed, or keen-edged object will work.pointed, or keen-edged object will work.

Stab Wounds Should be Described Stab Wounds Should be Described at Autopsy:at Autopsy:

• Site relative to local anatomical landmarks as well as Site relative to local anatomical landmarks as well as its distance from the midline and above the heel (or its distance from the midline and above the heel (or below the crown of the head).below the crown of the head).

• Shape and Size including the dimensions with the Shape and Size including the dimensions with the wound edges closed back.wound edges closed back.

• Direction (approximately) in three dimensions.Direction (approximately) in three dimensions.

• Depth of the wound track at autopsy.Depth of the wound track at autopsy.

• Damage to tissues and organs along the wound track.Damage to tissues and organs along the wound track.

• Effects of damage described above.Effects of damage described above.

Stab Wounds: Shape of WeaponStab Wounds: Shape of Weapon

• A knife blade with a double edge will normally A knife blade with a double edge will normally produce a symmetrical elliptical wound with both produce a symmetrical elliptical wound with both ends pointed, clean cut edges and without any ends pointed, clean cut edges and without any associated bruising or marginal abrasion.associated bruising or marginal abrasion.

• A knife with a single-edged blade may show relative A knife with a single-edged blade may show relative blunting ("fish-tailing") of one end of the entry slit. A blunting ("fish-tailing") of one end of the entry slit. A single edged blade can produce a wound with two single edged blade can produce a wound with two pointed ends, mimicking an injury from a double pointed ends, mimicking an injury from a double edged blade. edged blade.

• A bayonet, which has a ridge along the back of the A bayonet, which has a ridge along the back of the blade with a groove along each side, may produce a blade with a groove along each side, may produce a slit like an elongated letter "T".slit like an elongated letter "T".

Stab Wounds: Shape of WeaponStab Wounds: Shape of Weapon

• Stab wounds produced with relatively blunt Stab wounds produced with relatively blunt instruments such as pokers, closed scissors and instruments such as pokers, closed scissors and files, tend to bruise and scrape the wound margin. files, tend to bruise and scrape the wound margin.

• These blunter instruments also tend to lacerate, as These blunter instruments also tend to lacerate, as well as cleanly penetrate, the skin; the blunter the well as cleanly penetrate, the skin; the blunter the point of the instrument and the thicker its shaft, point of the instrument and the thicker its shaft, the more likely is the entry hole to become a the more likely is the entry hole to become a ragged, often cross shaped split.ragged, often cross shaped split.

• Forensic Pathologist sometimes practices wound Forensic Pathologist sometimes practices wound type: The Body Farm. type: The Body Farm.

Stab Wounds: Degree of Stab Wounds: Degree of ForceForce

• The most reliable estimate of blade width is made from The most reliable estimate of blade width is made from the deepest wound with the shortest skin surface length.the deepest wound with the shortest skin surface length.

• It is easy to over-estimate the amount of force required to It is easy to over-estimate the amount of force required to produce a stab wound. produce a stab wound.

• The depth of a wound is not generally an indication of the The depth of a wound is not generally an indication of the degree of force used.degree of force used.

Stab Wounds: Degree of Stab Wounds: Degree of ForceForce

• The most critical factor is the sharpness of the point of the The most critical factor is the sharpness of the point of the instrument; relatively little force is required to produce a stab instrument; relatively little force is required to produce a stab wound provided a knife with a sharp point. wound provided a knife with a sharp point.

• After clothing, the skin offers the greatest resistance to After clothing, the skin offers the greatest resistance to penetration; once this is overcome, then the blade easily cuts penetration; once this is overcome, then the blade easily cuts into deeper tissue.into deeper tissue.

Stab Wounds: Degree of Stab Wounds: Degree of ForceForce

• The penetration of bone does imply a significant degree of force.The penetration of bone does imply a significant degree of force.

• The tip of the blade may break off when driven into bone and The tip of the blade may break off when driven into bone and should be recovered for matching with the weapon. should be recovered for matching with the weapon.

• In estimating the force exerted by an assailant, consideration In estimating the force exerted by an assailant, consideration should be given to the possibility of counter pressure by the should be given to the possibility of counter pressure by the victim, e.g. running or falling forwards.victim, e.g. running or falling forwards.

Stab Wounds: Length of WeaponStab Wounds: Length of Weapon

• The depth of the wound (the length of the wound track, The depth of the wound (the length of the wound track, provides some indication of the length of the stabbing provides some indication of the length of the stabbing instrument). instrument).

• The wound track length may be less than the length of the The wound track length may be less than the length of the instrument if the weapon was not thrust into the body to instrument if the weapon was not thrust into the body to its full length.its full length.

• The wound track can be longer than the knife if there is The wound track can be longer than the knife if there is force compressing tissues. force compressing tissues.

Stab Wounds: ClothingStab Wounds: Clothing

• Cuts on the clothing should be noted and correlated Cuts on the clothing should be noted and correlated with injuries to the body.with injuries to the body.

• More than one cut on the clothing may correspond More than one cut on the clothing may correspond with a single injury to the body as a result of folds in with a single injury to the body as a result of folds in the clothing.the clothing.

• Cuts to the clothing may not exactly overlie Cuts to the clothing may not exactly overlie corresponding wounds to the body.corresponding wounds to the body.

• There may be stab or slash marks on the clothing There may be stab or slash marks on the clothing without corresponding injuries to the body, e.g. without corresponding injuries to the body, e.g. "defense"-type slashes to the arms. "defense"-type slashes to the arms.

Stab Wounds: ClothingStab Wounds: Clothing

• Blood flow patterns on the clothing may indicate the Blood flow patterns on the clothing may indicate the position of the victim at the time of the stabbing. position of the victim at the time of the stabbing. • Blood drops on the tops of the shoes from a stab to the chest Blood drops on the tops of the shoes from a stab to the chest

in a victim standing upright.in a victim standing upright.• Blood flow direction can change with movements of the Blood flow direction can change with movements of the

body.body.

• Wound track can be indicated by undercutting and Wound track can be indicated by undercutting and beveling of the external wound. beveling of the external wound.

• Extrapolation from the direction of wound tracks to an Extrapolation from the direction of wound tracks to an opinion on the relative positions of an assailant and opinion on the relative positions of an assailant and victim should be, since two potentially moving victim should be, since two potentially moving objects are involved.objects are involved.

Stab Wounds: Cause of DeathStab Wounds: Cause of Death

• Most deaths from stab wounds are homicides.Most deaths from stab wounds are homicides.

• Homicidal stab wounds are usually multiple, Homicidal stab wounds are usually multiple, since most wounds leave the victim capable of since most wounds leave the victim capable of some resistance for a measurable time during some resistance for a measurable time during which the thrusts are repeated.which the thrusts are repeated.

• Single homicidal stabbings are often associated Single homicidal stabbings are often associated with drugged, drunk, sleeping, or otherwise with drugged, drunk, sleeping, or otherwise partially incapacitated victims and are almost partially incapacitated victims and are almost always aimed at the heart.always aimed at the heart.

Stab Wounds: Cause of DeathStab Wounds: Cause of Death

• Homicidal stab wounds to the chest are all likely to be deep, Homicidal stab wounds to the chest are all likely to be deep, penetrating the chest wall, and more than one may be lethal. penetrating the chest wall, and more than one may be lethal.

• Stabs in the back strongly suggest homicide. Stabs in the back strongly suggest homicide.

• In cases of multiple scattered stabs, the larger the number the In cases of multiple scattered stabs, the larger the number the greater the certainty of murder.greater the certainty of murder.

• There is often a sexual motive to deaths with this type of There is often a sexual motive to deaths with this type of "over-kill". "over-kill".

Defense Stab WoundsDefense Stab Wounds

• "Defense wounds" are the result of the immediate and "Defense wounds" are the result of the immediate and instinctive reaction of a victim to ward off anticipated injuries instinctive reaction of a victim to ward off anticipated injuries and may be seen in both homicidal and accidental deaths. and may be seen in both homicidal and accidental deaths.

• Defense wounds result from raising the arm to ward off the Defense wounds result from raising the arm to ward off the attack or attempts to grasp the weapon. attack or attempts to grasp the weapon.

• The resulting injuries may be stabs or slashes or both. The resulting injuries may be stabs or slashes or both.

Defense Stab WoundsDefense Stab Wounds

• Attempts to grab the knife results in deep cuts to the Attempts to grab the knife results in deep cuts to the palm of the hand and the palm side of fingers. palm of the hand and the palm side of fingers.

• With the hand in a gripping position the palm skin is With the hand in a gripping position the palm skin is loose and folded so that resultant cuts appear irregular loose and folded so that resultant cuts appear irregular and ragged. and ragged.

• They may be duplicated by the thrust and withdrawal They may be duplicated by the thrust and withdrawal of the weapon. of the weapon.

• Penetration of the hand or arm is also a defense Penetration of the hand or arm is also a defense wound.wound.

• The absence of defense wounds does not exclude The absence of defense wounds does not exclude homicide since the victim may be incapable of homicide since the victim may be incapable of effective defense.effective defense.

Suicidal Stab WoundsSuicidal Stab Wounds

• Suicide by stabbing is distinctive. The wounds, if Suicide by stabbing is distinctive. The wounds, if multiple, have a location and direction accessible to multiple, have a location and direction accessible to the victim and are typically grouped in the "pit" of the the victim and are typically grouped in the "pit" of the stomach.stomach.

• Use of one hand is indicated by a consistent direction Use of one hand is indicated by a consistent direction of penetration.of penetration.

• Multiple wound tracks extending from the same slit in Multiple wound tracks extending from the same slit in the skin reflects partial withdrawal of the weapon and the skin reflects partial withdrawal of the weapon and further thrusts (possibly trial feelers), and suggests further thrusts (possibly trial feelers), and suggests possible suicide. possible suicide.

Suicidal Stab WoundsSuicidal Stab Wounds

• Typically a suicidal stabbing is to the bare skin Typically a suicidal stabbing is to the bare skin and the clothing may be removed or pulled aside and the clothing may be removed or pulled aside to effect this. to effect this.

• Defense wounds do not occur in suicide, although Defense wounds do not occur in suicide, although the sharpness of a knife may be tested by running the sharpness of a knife may be tested by running the blade across the tips of the fingers. the blade across the tips of the fingers.

• Multiple scattered wounds weighs against suicide Multiple scattered wounds weighs against suicide unless there was serious mental illness. unless there was serious mental illness.

Suicidal Stab WoundsSuicidal Stab Wounds

• Fatalities from a single stab wound can be Fatalities from a single stab wound can be difficult and such a wound may be homicidal, difficult and such a wound may be homicidal, suicidal, or accidental. suicidal, or accidental.

• Autopsy findings should always be interpreted in Autopsy findings should always be interpreted in the light of information concerning the the light of information concerning the circumstances and scene of death. circumstances and scene of death.

• If the stab wound was inflicted during a fight If the stab wound was inflicted during a fight then the usual defense is that it was accidental, then the usual defense is that it was accidental, the victim having ran or fallen on to the weapon.the victim having ran or fallen on to the weapon.

• The position and direction of the wound may help The position and direction of the wound may help resolve the issue.resolve the issue.

Stab vs SlashStab vs Slash

• Stab wounds are deep and not wide.Stab wounds are deep and not wide.

• Slash wounds are wide and not deep.Slash wounds are wide and not deep.

Penetrating Wounds (Punctures)Penetrating Wounds (Punctures)

• Breach in full skin thickness and depth is greater than Breach in full skin thickness and depth is greater than lengthlength

• Long, thin, sharp or blunt object.Long, thin, sharp or blunt object.

• If sharp object then equals "stab wound". If sharp object then equals "stab wound".

Lacerations (Tears, Splits)Lacerations (Tears, Splits)

• Splitting of the skin by the direct crushing of blunt Splitting of the skin by the direct crushing of blunt trauma.trauma.

• Typically over bone, e.g. scalp, eyebrow, cheekbone.Typically over bone, e.g. scalp, eyebrow, cheekbone.

LacerationsLacerations

• Distinguished from incised wounds by:Distinguished from incised wounds by:• Adjacent abrasion/bruiseAdjacent abrasion/bruise

• Ragged edgeRagged edge

• Tissue bridges in depthTissue bridges in depth

• Forensic ImportanceForensic Importance • Not related to object shape Not related to object shape • Trace evidence Trace evidence • Relatively little blood loss (except scalp) Relatively little blood loss (except scalp) • Rarely suicidalRarely suicidal

LacerationsLacerations

•Typical ExamplesTypical Examples• Stellate pattern from poker end Stellate pattern from poker end •Circles/crescents from hammer Circles/crescents from hammer •Y-shaped from metal rod Y-shaped from metal rod • Inside lips from blow to mouth. Inside lips from blow to mouth. • Stretching lacerations in vehicular Stretching lacerations in vehicular

accidents.accidents.

Bite MarksBite Marks

• Double crescent of abrasions and bruisesDouble crescent of abrasions and bruises

• Early Examination, loss of definitionEarly Examination, loss of definition

• Swab for saliva, photographSwab for saliva, photograph

• Comparative valueComparative value

• Child abuse, sexual assault.Child abuse, sexual assault.