Forensics Flashcards
COD vs mechanism vs manner?
COD = the true underlying cause (why?)
ex. HIV
mechanism = (how?) = immediate cause of death
ex. cardiac arrest, shock, hypovolemic shock
manner of death: NASHU
wounding formula
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
abrasions
- “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
lacerations
= blunt force injury
- see tissue bridging in deeper portion of injury
contusions
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
incise wounds/stab wounds
- 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
shotgun wounds
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
ionizing radiation
generally see leukemias and lymphomas
three types of blunt force injuries?
- abrasion= scrapes
- contusion = bruise
- laceration = breaking of skin due to blunt force
what color can you age body off of?
yellow: indicates bruise is at least 18 hours old or older
- blue/purple/red/brown do NOT assist in dating bruises
three types of abrasions?
- 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
- 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
- patterned abrasion: : patterns of what presses on you at a high force
dicing injuries
seen in vehicular accidents – passenger injuries (seen on the side window injury – breaks into small pieces)
military vs. civilian wounds
- A lot of military knives are double edged (more circular)
- Single bladed knife should have a squared off triangular appearance (civilian knives)
Contact shot /”close”
- see marginal abrasion
- see imprint of gun muzzle surrounding the shot, may see powder in depths of wound
Intermediate shot
- 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
Distance shot
no soot or stippling, no gunpowder surrounding the skin
Head shot
Entry: outer table is sharply circumscribed, inner table is bevelled
Exit: inner table is sharply circumscribed, outer table is bevelled
specimen retrieval:
organic materials = paper bags (plastic + water + sun = great decomposition)
inorganic materials = plastic bags
severity in contusion depends on?
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.
high velocity weapons
large exit wound
rifle shot = long gun
putrefactive decomposition
endogenous GI flora streams through and see patch of green in RLQ, secondarily insects gain access
- usually occurs 3-4 days at RT
adipocere formation
decomposition occuring in water
- skin degrades and get fat saponification on exterior surface
- note: more painful to die in fresh water, and more quick
algor mortis
- 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.
rigor mortis
- 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
