1. Investigation of Injury

2. Anatomical Positions: Planes
Sagittal
Plane
Transverse
Plane
Coronal
Plane

3. Anatomical Position Right and left is the victim’s right and left
Cranial v. caudal
Inferior v. superior
Ventral v. dorsal
Anterior v. posterior
Lateral v. medial
Proximal v. distal

4. Physical Trauma The extent and appearance of the injuries depend on:
The amount of force applied to the body
The weapon’s surface area and mass
The part of the body affected

5. Force Force is a push or a pull applied to an object
Describes how hard the weapon hit the victim
Force=mass x acceleration or F=ma
Acceleration is the change in velocity over a period of time.
An object moving quicker will cause a more serious injury

6. Practice problem
If a 1000kg car traveling at 10m/s2 or (45mph with 2 seconds to stop), what would be the force of the impact if it crashed into a wall?
F=ma
F= (1000kg)(10m/s2)
F=10,000kg(m/s2) or 10,000 Newtons
What if the speed was increased to 90mph?

7. Surface area and pressure
If the same amount of force is exerted over a larger surface area, the injury will be less severe.
Pressure= amount of force per unit area
Pressure=force/surface area
The force of a palm pushing against a wall is less that the force of a closed fist (decrease surface area=increase pressure/force)

8. Surface area, Pressure, and force
A weapon with a larger surface area will inflict a less severe injury (if same force is applied)
What would have more force:
A narrow metal rod vs. a flat wooden board?
Answer: flat wooden board=more surface area=larger surface area
What would be more prone to severe trauma:
The skull vs. the back?
Answer: the skull=the back has more contact with the weapon=lower pressure=less severe

9. Blunt Force Trauma
An injury resulting from an impact with a dull, firm object or surface
Categories of blunt force trauma:
Abrasions
Contusions
Lacerations

10. Abrasion
A scraping injury to the superficial layers (epidermis) of the skin resulting from friction against a rough surface
Usually not deep, heal quickly
While alive: reddish-brown
Post-mortem: yellow, almost transparent
Abrasions can be;
Brush-force is parallel to skin
Impact-force is perpendicular to skin
Patterned-brush abrasion that causes an imprint on skin

11. Abrasions

12. Contusion (bruise)
Hemorrhage into the dermis, subcutaneous tissues, deep soft tissues, and internal organs resulting from a rupture of blood vessels
Hematoma: swelling as a result of blood collecting
Patterned contusion: the bruise looks similar to the object that produces it

13. Contusions

14. Ecchymosis
Discoloration caused by the escape of blood into the tissues
May or may not be trauma-related, particularly in the elderly

15. Laceration
A tearing or bursting of the tissue resulting from compression or stretching associated with impact from a blunt object or surface
Tissue-bridging may occur where the skin splits but the arteries do not forming a ‘bridge’ across the wound

16. Tissue Bridging

17. Avulsion Refers to a tearing away or detachment of a body structure
Commonly used to describe skin that has been torn away, exposing underlying tissues.

19. Sharp Force Trauma
An injury produced by a pointed or sharp-edged object, and characterized by a relatively well-defined separation of tissues
Types:
Stab/puncture wound
Incised/cut wound
Chop wound

20. Stab/Puncture Wounds
Direction of force relatively perpendicular to skin surface

21. Stab/Puncture Wounds
1.5"
Depth of wound generally greater than length on skin surface
Depth of wound can be greater than the length of blade that caused it.
4"
3.5"

22. Stab wound
Slit-Like Wound
Gaping Wound

23. Incised/Cut wounds Sharp instrument is drawn across the skin surface
Depth of wound is less than length on skin surface
4"
1/2"

24. Cut/incised wound

25. Combination of blunt and sharp force injury
Chop wounds
Combination of blunt and sharp force injury
Can result in abrasions, lacerations, cuts, and/or fractures
Axes, hatchets, propellers, lawn mower blades

26. Chop Wounds
Abraded Margins

27. Gun Shot Injuries Contact wound Near contact wound
Gun is in contact with victim
Near contact wound
Gun is very near victim

29. Gunshot Injuries Intermediate-range wound Distant wound
Gun is 3” to 3-4 feet away
Powder tattooing (stippling)
Distant wound
Gun is >3-4 feet away
A few inches – 3 to 4 feet
> 3 to 4 feet

30. Powder Tattooing (Stippling)

31. Gun Shot Injuries Entrance Exit Smaller wound Larger wound
Entrance vs Exit
Entrance
Exit
Smaller wound
Larger wound
Circular, punched-out appearance
Jagged edges
Abrasion ring
No abrasion ring

32. Entrance
Abrasion Ring
Exit

33. Gunshot injuries Penetration: entrance, but no exit
Perforation: entrance and exit

34. Patterned Injuries
An injury (generally an abrasion or contusion) that reproduces some of the features of the impacting object
Potential misinterpretations
Mongolian spots-found on babies, not the result of abuse
Periorbital ecchymosis-naturally occurring around eyes
Senile pupura

35. Patterned injuries Senile Purpura Congenital dermal melanocytosis
Periorbital Ecchymosis

36. Many slides and images taken from “Medicolegal Terminology Associated with Wounds Sustained by Victims of Violent Crimes” by Jeff Saviano
Jeff Saviano, CFC, CMI
Criminalist/Owner
JDS Criminalistics, LLC