Forensics Flashcards
What are the different types of blunt force injuries?
- Abhrasion
- Contusion
- Laceration
What is an abrasion?
Blunt force injury where (primary) the epidermis was injured.
How is a abrasion made?
- Friction scraping away the epidermis
- Crushing by direct force
- Blow tangential to the skin
How do abrasions present
ooze and bleed (but not profusely)
heals by forming a scap
What are the different types of abrasions?
- brush (scrape or gliding)
- impact
- patterrned
what is a brush abrasion?
what will you see?
Abrasion d/t scraping/gliding (tangential force applied to the body).
rolls, heaps of tissue OPPOSITE to the direction of force.
Large scrapes “brush burns”
What is a patterned abrasion?
when an impact leaves a pattern on the skin
When will you see brush abrasions?
motorcycle accidents
What are dicing injuries?
dicing on left side means face was on passenger window to left
front windshield will split and passenger will break into small dicing structures
Laceration
(blunt force to body surface that splits skin)
frequently see soft tissue bridges
What is the wounding formula?
- shorter time and smaller area => WORSE
W= E * K * 1/T * 1/A
E= energy transferred (1/2 mV^2)
K= modify facitor (elasticity of striking object or tissue being injured)
T= period (time) of NRG transfer
A= areas of application of force
Contusion
“A contusion is a bruise d/t
hemorrhage => soft tissue due to rupture of subcutaneous blood vessels by blunt force
injury
Why do contusions not bleed out?
epidermis is intact
Where can contusions be seen?
skin or deep viscera (internal organs)
What does the extent and severity of a contusion correlate with?
- Amount of force
- Vasculature of the tissue injired
- Type of injury
- Location of the tissue: is it over bone
- Are you easily bruised? Age, cirrhosis, blood problems
Can the age of a contusion be predicted based Upton the color change?
YES: but only when yellow: tells us the bruise is older than 18 hours
Blue, purple and red do not help
brown is just a mixture of colors, so no
stab wound/ (incise wound)
SHARP FORCE INJURY where the depth of the injury is greater than the length
deeper than longer
how is a stab wound made?
instrument with pointed edge is thrusted onto body; object is longer than puncture and deeper than it is wide
fall on a pointy object
what is a stabbing instrument?
anything that can overcome tensile stretnth of the skin
scissors, screwdrivers, BBQ foks
Single edged blade will make a ______ shaped incision, while
a double edged blade will make more of a______injury
Single: triangular
Double: round diamond
To tell what hand someone stabs: ______
you tend to reach up higher with dominant hand
What are examples of long guns
- bolt/lever action
- semi-automatic
- fully automatic
Other types of guns
- Smooth bores
2. Hand guns: revolvers and semiautomatics
Characteristics of a gun wound?
_____ = more powder
Which is more important: velocity or mass of the bullet?
Rifling produces what kind of bullet?
- closer=more powder
- velocity is more important than mass
- rifling=spinning bullet
___ guns fire with more velocity => more damage.
Long
Which bullets go faster: bigger or smaller
bigger, even if they are bigger
which guns have more wounding ability?
long
do only bullets come out of gun?
no
The adult skull has a inner and outer table, separated by a diploe.
In entry wounds, what do they look like?
Outer table: circumscribed (sharp)
Inner table: beveled
The adult skull has a inner and outer table, separated by a diploe.
In exit wounds, what do they look like?
Outer table: beveled
Inner table: circumscribed
Exit skull GSW are opposite
What is unique about blunt force to the head (and in some cases GSW).
they do not cross previous fracture lines (they stop, rather than cross). thus you can time when the wound happaned.
marginal abrasion, dirt, powder grains, and soot in the depths of the wound
contact wound
marginal abrasion, stippling and powder tattooing pattern;
on skin you can see powder (intermediate zone) and the gunshot wound of entry
intermediate wounds
marginal abrasion
no powder soot stippling
no powder soot IN wounds
distant wounds
What can we say about entry and exit of
handguns (low velocity);
long guns (high velocity?
hand guns (low v) => pt presents with a small entrance wound and a small/no exit wounnd
long guns (high v) => relatively small entry=> BIG exit
the faster an object hits someone the ___ damage it will cause and a _____ area of the same density will cause MORE damage d/t inverse relationship
MORE
SMALLER
What is the macro level approach to mass casualties?
Macro: the scene
- Safeguarding (protect live people first - then the scene)
- Surveying
- Documenting
- Proper approach to specimen retrieval
What is the micro level approach to mass casualties
Retrive biologic materials and transmittal vs. inorganic specimens/substances
use paperbag for organic compounds
What can degrade DNA
water and UV light (use paper bag t0 avoid precipitation)
In Waco, who showed up in
Feb of 1993?
BATF
Burea of alcohol, tobacco and firearm
In Waco, who showed up in
April of 1993?
FBI
What is the role of the ME?
do they have a duty to the family?
- assign a cause of death (COD)
- To render an opinion as to the manner of death
no
Is cardiorespiratory arrest ever a legitimate cause of death?
NO => jjust means <3 and lungs stopped working
If a case appears obvious, why do a forensic autopsy?
anybody can allege anything
- confined a disease that contributes, (neurotic, cutters)
- need to protect society
cause of death
proximate
what initated everything: REAL COD
gunshot
mechanism of death
immediate COD
pathophysiology of the COD
manner of death
NASHU
how do we write
[mechanism of death] due to [COD] ______
manner of death
________ of death is a judicial opinion determined by the pathologist that is based off of everything we know. It can change as we get more information
Manner of death
NASHU
Cause of death is determined by an _____
autopsy
List and carefully describe manners of death, i.e. natural, accident, suicide and homicide. Answer the question: Is it ever legitimate to formally list a manner of death as “undetermined”?
Manner of death CAN be marked as undetermined because some people can die d/t idiopathic causes.
- Explain, with examples, why homicide and murder are not synonymous terms.
Homicide: a life that was taken by person OR ENTITY.
• Thus, lethal injection is a homicide (euthenasia)
what is the focus of forensic examination/inquiry
not natural disease (even though taken into account) but foul play and unnatural death are the focus
why do hospitals do less autopsies
we dont known an unknown undiagnosed disease to get discvovered
or get sued (everyone can get sued except ME
time consuming
expensive
When we die, body undergoes what changes
stiffens
cools
collects pools of blood determined by body position
Rigor mortis: body _____
Algor mortis: body _____
Livor mortis: body _____:
rigor mortis = body stiffening
algor mortis => body cooling
livor mortis = body postioning (LP) and collec
[Q:] if the body temperature is warm, and there is no stiffness, how long ago did the patient die?
0-3
[Q:] if the body temperature is warm, and there IS stiffness, how long ago did the patient die?
3-8
[Q:] if the body temperature is cold, and there IS stiffness, how long ago did the patient die?
8-36
[Q:] if the body temperature is cold, and there NO stiffness, how long ago did the patient die?
More than 36 hours; remember the body is reduced to gas and water and skin begins to slip.
- Describe the major forms of body decomposition (3) and the settings in which they occur.
- putrerifactive = most common
- adipocere formation
- mummification
• Putrefactive
warm places (humid)
starts in RLQ (colon) => microbes invade => proliferate=> green colon => body is reduced to gas and water and skin slips
• Adipocere formation
occurs when we are in water for a long period of time
epiderms degrades
fatty deposits
• Mummification
body dries up with no gas formation
