Sharp Force Injuries Sharp force injuries~ Caused by a sharp object that cuts & divides tissues; wound edges may be straight or jaggedCaused by a sharp object that cuts & divides tissues; wound edges may be straight or jagged 3 types of wounds: stab (puncture), incised (cuts or slash), & chop wounds3 types of wounds: stab (puncture), incised (cuts or slash), & chop wounds Stab wound= a wound made by a sharp object that goes deeper into the body than its length on the skin surfaceStab wound= a wound made by a sharp object that goes deeper into the body than its length on the skin surface Incised wound= a wound made by a sharp object that is longer on the skin surface than it is deepIncised wound= a wound made by a sharp object that is longer on the skin surface than it is deep Chop wound= wound made by a heavy sharp object (axe, meat cleaver, machete)Chop wound= wound made by a heavy sharp object (axe, meat cleaver, machete)

Information from sharp force injuries Information obtained from sharp force injuries~ Direction- determined by careful dissection of woundDirection- determined by careful dissection of wound Dimensions of the weapon or instrumentDimensions of the weapon or instrument Length & width of blade cannot be determined from woundLength & width of blade cannot be determined from wound Depth of wound can be measured, but doesn’t indicate length of bladeDepth of wound can be measured, but doesn’t indicate length of blade Thickness of blade can be determined by bringing the wound edges parallelThickness of blade can be determined by bringing the wound edges parallel Pattern injuries- may help identify the weaponPattern injuries- may help identify the weapon Damages- may help determine the length of survivalDamages- may help determine the length of survival Cause of death (process that initiates the chain of events that results in death)~ Ex., stab wound of chest, incised wound of neckEx., stab wound of chest, incised wound of neck

Mechanisms of death Pathophysiological abnormality resulting in death~ Exsanguination (bleeding or hemorrhage)= internal bleeding, most common mech. of death due to sharp force injuriesExsanguination (bleeding or hemorrhage)= internal bleeding, most common mech. of death due to sharp force injuries Asphyxia= bleeding into airway, which then block airwaysAsphyxia= bleeding into airway, which then block airways Ex., throat cut, causing blood to enter lungsEx., throat cut, causing blood to enter lungs Cardiac tamponade= blood in pericardial sac compresses heart, causing it to be unable to pump out bloodCardiac tamponade= blood in pericardial sac compresses heart, causing it to be unable to pump out blood Air embolism= cutting jugular vein (or other large vein) allows air into venous system that is pumped into lungsAir embolism= cutting jugular vein (or other large vein) allows air into venous system that is pumped into lungs Ex., wrist cut, air travels back to right atrium & causes heart attackEx., wrist cut, air travels back to right atrium & causes heart attack Infection= death may occur days-months after injuryInfection= death may occur days-months after injury

Incised wounds Incised wounds differ from the following: Lacerations due to absence of bridging fibersLacerations due to absence of bridging fibers Stab wounds by being longer than deepStab wounds by being longer than deep Typical weapons, objects producing incised wounds~ Knives, slashing weapons (machetes, swords), sharp objects (broken bottle, razor wire)Knives, slashing weapons (machetes, swords), sharp objects (broken bottle, razor wire) Sharp surfaces will produce clean, well-defined edges of woundSharp surfaces will produce clean, well-defined edges of wound Dull surfaces produce abraded edges & bruisingDull surfaces produce abraded edges & bruising Start of wound typically the deepest, so can determine direction of blow Replicate wound in lab using variety of knivesReplicate wound in lab using variety of knives

Incised wounds (cont.) Suicide –vs- violent attack~ Suicide victim may test personal resolve &/or sharpness of weapon on fingers or parallel cuts on wrist/neck prior to fatal incisionSuicide victim may test personal resolve &/or sharpness of weapon on fingers or parallel cuts on wrist/neck prior to fatal incision Incisions on neck tend to begin high on opposite side of neck (from cutting hand) & dragged downwards across throatIncisions on neck tend to begin high on opposite side of neck (from cutting hand) & dragged downwards across throat Cutting carotid artery, hyoid bone, thyroid cartilageCutting carotid artery, hyoid bone, thyroid cartilage Violent attacks lack tentative incisions & may have 2+ cutsViolent attacks lack tentative incisions & may have 2+ cuts Cuts usually forceful & across throat; beginning direction depends on position of assailant & handednessCuts usually forceful & across throat; beginning direction depends on position of assailant & handedness Larynx & all major blood vessels likely severedLarynx & all major blood vessels likely severed Healed incised wounds, surgical scars may help id victim

Stab wounds Stab (puncture) wounds are deeper than wide~ ‘Any thin, rigid object’ can produce stab wounds if thrust w/ enough force‘Any thin, rigid object’ can produce stab wounds if thrust w/ enough force Many weapons can either produce stab or incised wounds, depending on how usedMany weapons can either produce stab or incised wounds, depending on how used Clothing, buttons, items in pocket can provide some protection & can cause ‘unusual wound tracks’Clothing, buttons, items in pocket can provide some protection & can cause ‘unusual wound tracks’ Stabbing victims should always be examined 1 st w/ clothing on since they may provide info regarding victim’s time of injuryStabbing victims should always be examined 1 st w/ clothing on since they may provide info regarding victim’s time of injury Ex., raised arms during an attack will puncture clothing of lower abdomenEx., raised arms during an attack will puncture clothing of lower abdomen Bloodstains on clothing also can indicate body positionBloodstains on clothing also can indicate body position Single-bladed knives produce a V-shaped profileSingle-bladed knives produce a V-shaped profile Serrated knives produce wounds w/ 1 edge torn & laceratedSerrated knives produce wounds w/ 1 edge torn & lacerated

Stab wounds (cont.) Single stab wounds may indicate: Accidental stabbings (kitchen, workplace) typically involve 1 woundAccidental stabbings (kitchen, workplace) typically involve 1 wound Homicides where victim was asleep, incapacitated (elder, drugged, drunk, etc.)Homicides where victim was asleep, incapacitated (elder, drugged, drunk, etc.) Blow delivered w/ care & precisionBlow delivered w/ care & precision Opposite typically occurs if awake & able-bodied: 1 st blow tends to not be fatal, thus multiple wounds; defensive wounds of arms, hands, palmsOpposite typically occurs if awake & able-bodied: 1 st blow tends to not be fatal, thus multiple wounds; defensive wounds of arms, hands, palms Suicidal stabbings typically heart or abdominal region where the weapon is thrust upwards toward the heartSuicidal stabbings typically heart or abdominal region where the weapon is thrust upwards toward the heart Weapon may be partially withdrawn & reinserted several times; possible 2+ stab woundsWeapon may be partially withdrawn & reinserted several times; possible 2+ stab wounds No defensive woundsNo defensive wounds

Other wound types associated w/ sharp objects Chop wounds~ Wound made by a heavy sharp object (axe, meat cleaver) that may produce a large, gaping wound w/ some characteristics of a blunt object wound edges, etc.)Wound made by a heavy sharp object (axe, meat cleaver) that may produce a large, gaping wound w/ some characteristics of a blunt object wound edges, etc.) V-shaped wounds~ Formed when assailant twists knife in body or victim movesFormed when assailant twists knife in body or victim moves Defense wounds~ Cuts or slashes from a sharp object, usually on hands, forearms as victim tries to ward off thrusts from knife, weaponCuts or slashes from a sharp object, usually on hands, forearms as victim tries to ward off thrusts from knife, weapon Hesitation wounds~ Superficial cuts (or stab wounds) consistent w/ suicide as the manner of death; usually on wrist, throatSuperficial cuts (or stab wounds) consistent w/ suicide as the manner of death; usually on wrist, throat

Other wound types associated w/ sharp objects (cont.) Abrasions, blunt object injuries w/ stabbings~ Usually not seen except where handle or hilt of knife impacts skinUsually not seen except where handle or hilt of knife impacts skin May be seen w/ chop woundsMay be seen w/ chop wounds Pattern injury may result from stabbing w/ unique instrument (helps id weapon)Pattern injury may result from stabbing w/ unique instrument (helps id weapon) Stab defects in bone~ Defects in bone preserves thickness of bladeDefects in bone preserves thickness of blade May be only evidence of cause of death if skeletonizedMay be only evidence of cause of death if skeletonized