Forensics

Question 1

COD vs mechanism vs manner?

Answer 1

COD = the true underlying cause (why?)
ex. HIV

mechanism = (how?) = immediate cause of death
ex. cardiac arrest, shock, hypovolemic shock

manner of death: NASHU

Question 2

wounding formula

Answer 2

W= E x 1/T x 1/A x K

K = modifying factors (elasticity of the striking object or the tissue being injured etc)

E = Energy transferred = ½ MV2

T = Period of energy transfer (time)

A = Area of application of force

Question 3

abrasions

Answer 3

• “scrapes”
• abrasion is a wound in which the epidermis is injured. it is produced by friction scraping away epidermis or crushing of the epidermis by direct pressure or a blow tangential of the surface”
• may ooze, though doesn’t tend to bleed like venous

Question 4

lacerations

Answer 4

= blunt force injury

- see tissue bridging in deeper portion of injury

Question 5

contusions

Answer 5

bruise

• results from hemorrhage into soft tissue due to rupture of subcutaneous blood vessels by blunt force injury
• NOTE: epidermis remains in tact, and hence contusions don’t bleed externally
• areolar tissues (such as around eyes) tend to bleed more into the tissue layer

Question 6

incise wounds/stab wounds

Answer 6

• A stab wound is a sharp force injury in which the depth of wound is greater than the length of the wound on the skin (deeper than longer). It is produced when an instrument with a pointed edge is thrust into the body/or body falls on pointed edge
• Any sharp instrument capable of overcoming the tensile strength of the skin may be used to cause a stab wound

Question 7

shotgun wounds

Answer 7

shotguns have some device to hold the pellets, if shot closely the cup and was come out and may make an X shaped marking on the skin, will see pellets all throughout the tissue

Question 8

ionizing radiation

Answer 8

generally see leukemias and lymphomas

Question 9

three types of blunt force injuries?

Answer 9

1. abrasion= scrapes
2. contusion = bruise
3. laceration = breaking of skin due to blunt force

Question 10

what color can you age body off of?

Answer 10

yellow: indicates bruise is at least 18 hours old or older

- blue/purple/red/brown do NOT assist in dating bruises

Question 11

three types of abrasions?

Answer 11

1. brush/scrape/gliding abrasion: produced by grazing or sliding motions, the applied force is tangential to the body surface. close inspection reveals “rolls” or “heaps” of tissue at the margin of the wound opposite the dxn of force
2. Impact abrasion: injuries on bony prominences or structures that stick out result from falling: if someone is struck, they will get bleeding around the eyes most likely
3. patterned abrasion: : patterns of what presses on you at a high force

Question 12

dicing injuries

Answer 12

seen in vehicular accidents – passenger injuries (seen on the side window injury – breaks into small pieces)

Question 13

military vs. civilian wounds

Answer 13

• A lot of military knives are double edged (more circular)

- Single bladed knife should have a squared off triangular appearance (civilian knives)

Question 14

Contact shot /”close”

Answer 14

• see marginal abrasion

- see imprint of gun muzzle surrounding the shot, may see powder in depths of wound

Question 15

Intermediate shot

Answer 15

• see “stippling”
• see deposits of other materials surrounding the bullet wound
• irregular marginal tears can exist around the zone of abrasion, with stippled pattern surrounding the entry zone

Question 16

Distance shot

Answer 16

no soot or stippling, no gunpowder surrounding the skin

Question 17

Head shot

Answer 17

Entry: outer table is sharply circumscribed, inner table is bevelled

Exit: inner table is sharply circumscribed, outer table is bevelled

Question 18

specimen retrieval:

Answer 18

organic materials = paper bags (plastic + water + sun = great decomposition)

inorganic materials = plastic bags

Question 19

severity in contusion depends on?

Answer 19

a. Amount of force applied
b. Vascularity of tissue injured
c. Type of tissue injured: areolar (loose or thin) tissue such as the eyelids - tends to bleed more
d. Location of the tissue: tissue overlying hard bony structures is more easily bruised
e. Easy bruisability: advanced age, cirrhosis of the liver, coagulopathies, etc.

Question 20

high velocity weapons

Answer 20

large exit wound

rifle shot = long gun

Question 21

putrefactive decomposition

Answer 21

endogenous GI flora streams through and see patch of green in RLQ, secondarily insects gain access

• usually occurs 3-4 days at RT

Question 22

adipocere formation

Answer 22

decomposition occuring in water
- skin degrades and get fat saponification on exterior surface

• note: more painful to die in fresh water, and more quick

Question 23

algor mortis

Answer 23

• the reduction in body temperature following death. This is generally a steady decline until matching ambient temperature, although external factors can have a significant influence.

Question 24

rigor mortis

Answer 24

• stiffening of body, due to crosslinking of mm. fibers - doesn’t occur until 3-4 hours after death
• reaches peak at 24 hours, then disappears, called “ secondary flaccidity”
• in hotter temperatures, this process is greatly increased

Question 25

mummification

Answer 25

happens in hot dry areas

Question 26

livor mortis

Answer 26

• after death when there is no longer circulation, blood that remains in vasculature sinks down into body, after 3-4 hours it becomes fixed, gives an idea of position and how long body has been there
  (i. e. if they die on their back, then blood is fixed on their back)

Question 27

marginal abrasion

Answer 27

= gunshot wound of entry

Question 28

entry wounds

Answer 28

marginal abrasion (tears around the periphery)

• if high velocity, exits are larger than entries
• low velocity wounds results in exts same as entry (if there is not an exit, then it was a low velocity bullet)

Question 29

handguns

Answer 29

“revolvers” = rotating
“semiautomatics” = have a clip
“pistols”
- handguns are lower velocity (the longer the barrel, the higher the energy, thus the greater velocity)

Question 30

long guns

Answer 30

rifles
shot guns
- in longer guns, they have a longer bullet, thus they have concentrated energy and have a higher velocity