Medico-Legal Investigations

1. Medico-Legal Investigations Blunt Force Trauma

2. Blunt Force Trauma • There are Four Main Divisions of Blunt Force Type Injuries. They are: • Abrasions or scrapes: scratches and grazes • Contusions (leakage of blood from vessels = extravation) or Bruises • Extra = outside; vasa = vessel • Lacerations or Tears • Fractures of Bone(s)

3. Blunt Trauma • The severity of blunt trauma depends on: • Amount of force delivered • Time over which the force is delivered • Region struck • Extent of body surface struck • Nature of the Weapon

4. Blunt Trauma Wounds • If a weapon breaks on impact less energy is delivered to the body • If the body moves with the blow less energy is delivered to the body

5. Blunt Trauma Wounds • The larger the area over which the blow is delivered the less severe the injury • An object that projects from the weapon will deliver all of the force • Rounded portions of the body can sustain greater injuries

6. Blunt Trauma Wounds • Abrasions: • An injury in which there is removal of outer layers of tissue by compression or a sliding force • Indicates EXACT site of contact or impact • In living persons the wound will scab over and become dry and darken • Postmortem the wound is yellow with a parchment-like appearance

8. Blunt Trauma Wounds • There are three types of Abrasions: • Scrapes • Impact • Patterned

10. What is the Forensic Significance of Abrasions? • Indicates violence • Its shape gives an idea about the causal instrument • Bite abrasions take the pattern of the teeth • Site of abrasion denotes the type of crime • Age of abrasion can be estimated so the time of the incident is known • Helps in identification of the assailant as in bite abrasion

11. Blunt Trauma Wounds • Scrapes • A blunt objects takes off the top layers of skin • May go as deep as the dermis • Leakage of fluids (serosanguineous fluid) • The area is reddish brown and forms a scab

12. BFT

13. Blunt Trauma Wound • Impact Abrasions • The blunt force is perpendicular to the surface of the body • Mostly seen over bony process • Eyebrows • Cheekbone • Nose

15. BFT

16. Blunt Trauma Wound • Patterned Abrasions • This occurs when the object which impacts the body leaves an imprint or stamp on the skin • Be aware postmortem insect bites may resemble patterned abrasions

17. Blunt Trauma Wound • Dating Abrasions is a complicated process • Scab formation begins in 4-6 hrs and is usually complete in 18 hrs • The skin begins to regenerate within 72 hrs • Once the scab falls off the skin will remodel and become thinner after about 12 days

18. What is a Contusion? • Bleeding under intact skin due to heavy blunt instrument • Hemorrhage into the skin, the tissues under the skin or both • Caused by crushing or squeezing of tissue

19. Can you Differentiate Ante- and Postmortem Contusions? • Yes, • Ante mortem • Swelling present • Color change • Not washable • More tissue infiltration (diffuse)

20. Blunt Trauma Wound • Contusions (Bruising) • Leakage from ruptured, injured or traumatized blood vessels (cellular leakage as well) • Diffuses out into surrounding tissues (hematoma) • Sufficient BFT must have been applied to tear one or more vessels

21. Blunt Trauma Wound • Fresh Bruises & Trauma: • Age and color a bruise presents depends on certain factors • Bruises can vary in color (depending on person) • Age (Children and elderly bruise easier) • A bruise can appear or disappear depending on: • Oxygen levels • Blood pigment & breakdown of hemoglobin • Physical Health Antemortem • Localized area of injury • cancer leukemia • scurvy • Aspirin • Anticoagulants (cumadine, heparin, warfarin, etc.) • Temperature • Hemophilia

22. Blunt Trauma Wound Bruising Bruises can formulate easier in: Loose tissue Fat Older adults and/or children Women (less muscle mass) Disease of the vascular system

25. Blunt Trauma Wound • Dating Contusions: • This is not an exact science • Hemosiderin in macrophage • Bruises usually follow a color pattern but not always • Reddish-purple or bluish-purple to violet, green, dark yellow to greenish-yellow and then disappears • The edges of the bruise have the oldest colors

26. Blunt Trauma Wound • Bruising • May take minutes to days to present • Take photograph incrementally during this time • Bruises can mask natural color • Estimation of age of bruise can be difficult after death

27. BFT

28. BFT

29. What are the Diagnostic Features of Lacerations? • Bridging • Abraded Edges • Edges irregular • Contusions at edges • Hair crushed

31. Blunt Trauma Wound • Lacerations (Tears): • Tears in the skin due to pressure (BFT) are called lacerations • Lacerations are distinguished from incisions by “bridging” • Lacerations may or may not imprint the object used to create BFT • There may be no external signs of injury but avulsions may occur

32. Blunt Trauma Wound • Lacerations • The wound usually has ragged or abraded edges • Wound margins are irregularly shaped • BFT injuries often contain evidence (trace) embedded in wound • Paint, bark, fibers, grease, metals, rubber, etc. • May be scrapes and bruising around the wound as well

33. Blunt Trauma Wound

34. BFT

35. BFT

36. BFT

37. Blunt Trauma Wound • Defense Wounds due to BFT • Mainly abrasions and contusions • On back of hands, wrists, forearms

39. Blunt Trauma Wound • Fractures of Bone • Can determine “directionality” of the impact • Can present as clear breaks • Can present as compound fracture • Can present as hair-line fracture

41. Blunt Trauma Wound • Fractures of the Extremities • Direct Force • Blunt object impacts a long bone causing breaking of the bone on the opposite side of impact • May be crushing on side of impact if force is great enough

42. Blunt Trauma Wound • Direct Force • Penetrating Fractures • Large force acting on a small area • Gun shot wounds • Focal Fractures • Small force on a small area • Bat or pipe

43. Blunt Trauma Wound • Crush Fractures • Large force over a large area • Motor vehicle (bumper fractures)

44. Blunt Trauma Wound • Indirect Force • Produced by a force acting at a distance from the fracture site

45. Blunt Trauma Wound • Indirect Fractures • Traction Fractures – bone is broken by a violent contraction • Angulation Fractures – bone is twisted (spiral fracture) • Verticle compression Fractures – oblique fracture of long bones

46. BFT

47. Case Study • An elderly woman was discovered lying on her back in her sewing room. Rigor mortis was in its early stages. A prominent amount of blood was covering her face. At autopsy there were red-blue contusions to her chest and right side with associated lacerations of the spleen and liver. After washing her face, a patterned contusion of the left cheek was noted resembling a heel mark from a shoe or boot. There was no significant head trauma.

48. Case Study • Numerous photographs of the facial contusion was taken. • Within hours of the autopsy, a suspect was apprehended. He was present in the neighborhood the last day the woman was seen alive. He was wearing tennis shoes which the authorities confiscated for testing. Fingerprint powder was dusted on the soles.

49. Case Study • A transparency print was made, and the transparency was placed over the photograph of the facial wound. A criminalist determined the comparison was a positive match and the pathologist agreed. On the basis of these examinations the suspect was indicted. No other incriminating evidence was found against him. Should these interpretations have been made? Was there enough information to indict? If not what other evidence would you want them to collect?

50. Case Discussions • The approach by both the pathologist and criminalist were sound. Both looked at the shoes, transparency and photograph of the wound to make comparisons. A mark on the face can be matched with an offending weapon if the pattern is distinct. In this case, both examiners thought the match was perfect because the marks on the face corresponded to the depressed areas of the heel of a shoe.