INJURIES

Blunt Force Injury Wound produced by blunt impact tears, shears and crushes Falls or blows with a blunt instrument (hammer, bat, brick, fist, pipe) typically result in blunt injury 3 types Contusion Abrasion laceration

Contusion A bruise; signifies hemorrhage into the skin, the tissues under the skin or both Some are patterned because of their design or shape, others are patterned by their location, distribution and relationship of one bruise or another Color change: light bluish red after a few hours, dark purple occurs roughly within a week, at the end of which greenish-yellow and later brown discoloration appears

Contusion Disappearance of a bruise may be expected within 2 weeks to one month Time to disappear depends on size and extent of the bruise, its depth and local circulation

Abrasion Scraping and removal of the superficial layers of the skin Skin tags: small, whitish-gray flaps of the epidermis may remain attached to the end of the abraded area Can indicate the direction in which the scraping occurred Drying of area caused the initial pink, then pale yellow-brown color to change to dark brown, even black

Abrasion Graze: when a bullet sideswipes the body Scratch: caused by a sharp edge of fingernails Brush burn: caused by the frictional force of rubbing against a rough surface Often characteristically patterned, providing info regarding nature of force May not be identifiable if there was skin slippage

Laceration A tear in the tissue, which may be external (skin) or internal (such as a torn spleen) Force and its direction determine appearance, depth and associated injuries, such as fractures Undermining of the edges indicates direction of impact Ex. Hammer, bottle, fall, glancing blow

Laceration Tissue bridges: threads of tissue, consisting of nerves, elastic and connective tissue fibers and blood vessels, that run between opposing sides of tear Wound edges usually abraded that corresponds to that which made contact with the impacting surface Shape and dimensions of abraded area similar to weapon’s Lacerations that extend beyond area of actual contact are result of splitting of the skin, caused by intense crushing

Sharp Force Injury Wound produced by a sharp object that cuts and stabs leaving no tissue bridges 2 types Cut or incised wound Stab wound

Cut or Incised Wound Results whenever a sharp edged object is drawn over the skin Injury is longer than deep Edges may be straight or jagged depending on weapon but are never abraded or undermined Deepest where the weapon was first applied to skin

Cut or Incised Wound If cutting is done parallel to lines of cleavage (direction of muscles), the edges of the wound will remain together If cutting is done across the lines of cleavage, the wound will be gaping or open Defense wounds: cuts on upper extremities (hands, forearms) sustained when trying to protect self

Stab Wound Results from penetration of a pointed instrument causing a wound that is deeper than its length Usually no abrasion except when handle or hilt of knife or fist of person hits skin Same principle involving lines of cleavage Stab wounds are smaller than blade which caused it due to elasticity of the skin Cannot tell if knife was serrated or not

INJURY BY GUNFIRE

Contact Shots When gun is fired with muzzle against clothes or skin May see a ring around bullet hole if against clothing but not if against skin Shape is result of penetration of bullet and escape of flame and expanding gases Perforation will be larger than diameter of bullet Wound is dirty looking, skin edges are ragged and torn

Contact Shots Charring of skin tissue due to heat from muzzle Wound to head or over bones: cross-shaped or stellate wound Due to force of explosion and gases against skull there is an expansion under the scalp, producing a ragged and torn wound that is much larger than an exit wound

Contact Shots May see muzzle stamp Muzzle of gun causes an abrasion outlining the muzzle if charring and destruction takes place under the skin

Close-Range Shots Fired from a distance at which gunpowder residue may be identified around a bullet hole Diameter and distance are related Larger diameter of GSR means distance from person was greater Distance can be evaluated only be test firing that particular weapon

Close-Range Shots Clothing may filter out soot and gunpowder particles but cotton and polyester T-shirts allow them to pass freely, causing small holes in the fabric Tattooing or stippling: pinpoint hemorrhages due to discharge of burned power, unburned powder or pieces of metal of bullet from blast are driven into skin Silencers reduce amount of gunsmoke

Distant Shots Fired from a distance at which gun smoke will not reach the target Cannot determine distance of shot Entrance Wound: Generally smaller than exit wound Typically round, neat hole with an abrasion collar and a gray or black ring around the edges Comparatively small amounts of blood

Distant Shots Exit Wound: Generally larger than entrance wound Ragged and torn in appearance, shreds of tissue extruding Generally a greater escape of blood than entrance and possible profuse bleeding Abrasion Collar: circular perforation and blackening effect on the edges of the skin as the bullet passes through

Shotgun Wounds: Rifle Wounds: Massive tissue destruction Wadding will usually be embedded in wound if fired within 10 feet Wadding can provide info about type of shot, guage of gun and possible evidence to identify gun used Rifle Wounds: Exit usually is large and ragged Entrance is same but have more internal damage

Asphyxia Condition that results in interference with the uptake of oxygen with failure to eliminate carbon dioxide Usually caused by/from Strangulation Hanging Drowning Inhalation of Poisonous Gases Suffocation or Smothering

Strangulation Choking of a person either manually or mechanically Cord, wire, etc. will leave an obvious groove on victim’s throat which resembles the mark on a hanging victim Can tell from fingernail marks if attack took place from front or rear of victim

Strangulation Damage to interior structures of neck, throat and larynx May see abrasions, bruises or fingernail marks Petechial hemorrhages: minute blood clots which appear as small red dots in the eyes Trauma to tongue from biting

Hanging A body need not be completely suspended in order to suffer asphyxia Deep groove across neck, usually high up Minute areas of bleeding due to rupture of small blood vessels in the skin will cause small black/blue marks to appear in area of groove line

Drowning Direct result of liquid entering the breathing passages, preventing air from going to lungs White foam forms as a result of mucus mixing with water If in water for long time will have damage from animals, rocks, etc. Submersion, panicky struggle, holding breath, inhalation of large volumes of water, swallowing of water, coughing, vomiting, unconsciousness, convulsions, respiratory arrest, heart failure

Inhalation of Poisonous Gases Depletion and replacement of oxygen with another gas Carbon monoxide Prevents oxygen from getting to tissues and from returning carbon dioxide to lungs Blisters containing clear fluid seen in the skin Hemorrhages in white matter of brain and in heart muscles

Inhalation of Poisonous Gases Cyanide: Poisons respiratory enzymes so can’t use oxygen Paralyzes vital functions and death occurs within seconds Hydrogen smells like bitter almonds Potassium or sodium cyanide causes corrosion of the stomach

Suffocation or Smothering Passage of air through mouth and nose is blocked May be evidence of scratches on face Autopsy findings: damage to lungs, petechiae, bruises and abrasions in the cheek and chin, hemorrhages and tears of the lining of the oral cavity

Electrocution Asphyxia if current flows through brain or spinal cord If current flows through the heart, fatal ventricular fibrillation and cardiac arrest may occur Burns may have a characteristic crater-like appearance with central charring or may look like 2nd and 3rd degree thermal burn or abrasion Blisters result from “cooking effect” on the tissue and represent channels through which steam exited