1. INJURIES

2. 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

3. 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

4. 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

5. 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

6. 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

7. 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

8. 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

9. 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

11. 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

12. 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

13. 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

14. INJURY BY GUNFIRE

15. 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

16. 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

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

18. 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

20. 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

21. 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

22. 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

23. 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

24. 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

25. 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

26. 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

27. 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

28. 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

29. 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

30. 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

31. 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

32. 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