Introduction to Forensics Flashcards
What is the purpose of beetles Forensic Entomology?
Beetles come after flies
Early arrivers (rove and carrion beetles) eat the immature flies
Late arrivers (hide beetles) eat the dried cadaver flesh
in terms of the types of “mortises” what is the order from first to last?
Heart stops
Blood collects in dependent locations (Livor Mortis)
Body stiffens (Rigor Mortis)
Body cools (Algor Mortis)
How does body temperature and stiffness play a role in determining time of death?
warm + not stiff = less than three hours
warm + stiff = 3-8 hours
cold + stiff = 8-36 hours
cold + not stiff = greater than 36 hours
What are the three main types of decomposition?
Putrefactive
Adipocere Formation
Mummification
What is the role of the medical examiner?
To assign the cause of death
To render an opinion as to the matter of death
What is NOT the focus of a forensic examination?
The focus is NOT examinations of natural death (other than to rule out/observe discernible signs) or consider circumstances in terms of the probability of foul play/unnatural death, or contributions thereof
What are types of mechanical force injuries?
abrasions
contusions
incise wounds
gunshot wounds
blast injury
What are the types of thermal injuries?
burns
hyperthermia (heat cramps/exhaustion/stroke)
hypothermia
What are the types of electrical injuries?
What are two other categories of injuries?
varies
includes low and high intensity
ionizing radiation
atmospheric pressure (decompression p128R)
What are the pros and cons of ionization radiation?
Pros:
treat cancer
diagnostic imaging
therapeutic/diagnositc imaging
Cons:
fibrosis
mutagenesis
carcinogenesis
teratogenesis
What is the dose-related response to total body irradiation?
Exposure to radiation of large areas even in small doses can cause problems
Doses less than 1Sv produce minimal sx
higher doses can cause acute radiation syndromes
What are the sx of acute radiation syndromes?
damage to hematopoietic, GI and CNS
hematopoietic and lymphoid systems are EXTREMELY susceptible
How is cause of death documented on a death certificate?
(Immediate) cause of death (mechanism)
due to
(proximate) cause of death
Manner of death
Is cardiorespiratory arrest ever a legitimate cause of death?
No
What are the three types of blunt force trauma?
abrasion
contusion
laceration
What is the wounding formula?
W = E x 1/T x 1/A x K
K = modifying factors (elasticity of the striking object or tissue being injured)
E = Energy transferred (1/2MV^2)
T = Period of energy transfer (time)
A = Area of application of force
Define a Contusion
a bruise that results from hemorrhage into soft tissue due to rupture of subcutaneous blood vessels by blunt force injury
- Can be found on skin and within deep viscera, no break in epidermis/outer layer
The extent/severity of a contusion depends on what five factors?
- amount of force applied
- vascularity of tissue
- type of tissue injured (loose/thin)
- location of the tissue (over bone, etc)
- easy bruisability (old age, etc)
What color of a contusion is the best for aging an injury?
yellow-indicates that bruis is 18 hours or older
blue/purple/red do not help in aging
brown is just a mix of colors-not helpful
Define Abrasion
an 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 to the surface.
(typically oozes, doesn’t normally bleed; heals via scab)
What are the three types of abrasion?
- brush (grazing/sliding motion with rolled margins opposite direction of force)
- impact abrasion
- patterned abrasion (recapitulation of the surface appearance of the injurious agent)
Define stab
A stab wound is a sharp fore injury in which the depth of the wound track 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 the body falls on the pointed edge.
What are some stabbing instruments?
knives, scissors, screw drivers, forks, BBQ forks (oddly specific)
note- an ice pick may appear as a small caliber firearm but won’t have bullent in soft tissue or typical exit wound
What are some types of guns (idk if this is high yield, but i also don’t know anything about guns)
Long guns: bolt/lever, semiauto, auto
Smooth bores
hand guns: revolvers, semiauto
What is the salient wounding formula for guns/projectiles?
KE = 1/2m x v^2
Velocity is more important than mass
What would you expect to find at the entry wound of a contact/close range
marginal abrasion; soot/powder in depths of wound
What would you expect to find at the entry wound of an intermediate range gunshot injury?
marginal abrasion, powder tattooing/stippling around wound
What would you expect to find at the entry site of a distant range gunshot wound?
marginal abrasion, no powder tattooing/stippling, no soot/powder in depths of wound
What does a entry wound look like in the outer table and inner table of the skull?
What about exit wounds?
outer table: sharply circumscribed
inner tabled: beveled
exit wounds are the exact opposite
What can we say about entery/exit wounds in terms of hand guns (low veolcity) vs. long guns (high velocity)?
low velocity- small entry, no or small exit
high velocity- relatively small entry, big exit
What is the macro level approach to securing the scene of a mass disaster?
safegaurding (first live, then scene)
surveying
documenting
proper approach to specimen retrieval
What are the micro-level approaches to securing a mass disaster scene?
biologic materials retrieval and transmittal vs. inorganic specimens/substances
What are the five principles for the scene/living in a mass disaster?
- control
- survey
- organize
- document
- evidence acquisition/securing
What is the role of the medical examiner in a mass disaster?
bodies
recording
final
(get more details from lecture)
Where does putrifactive decomposition occur?
What is the mechanism of spread?
temperate environments, typically outdoors in heat/humidity?
Bacteria from RLQ/cecum spreads throughout body turning tissues into liquid/gas
very smelly, green/black tissues, hard to exam
Where does adipocere formation decomposition occur?
In water
characterized by skin saponification
may have tissue eaten by fish
Where does mummification decomposition occur?
dry heat or dry cold
tissue dehydrate and are preserved
What is the manner of death?
What are the five options for manner of death (acronym)
Manner of death is the ME’s opinion on the way the patient died
N-Natural
A-Accidental
S-Suicide
H-Homicide
U-Undetermined
Who can determine manner of death?
Any liscensed physician can sign a certificate for natural death
ME’s determine manner of death other than natural
Coroners and MEs are the same
True/False?
False
A coroner is an elected position and may or may not be a physician (typically not)
ME are physicians, typically pathologists
Does the ME have duty to the families of the bodies?
No
MEs work for the public, like cops and firemen/women
this helps avoid issues with foul play by family members which is statistically concerning.
Why are fewer hospital autopsies done now adays compared to “the good ole days”?
Because of liability
(if something was missed by docs/MEs that is found by a teaching autopsy, it would be documented and families could sue)
Dr. P’s opinion of this is that it is bad because it takes away learning opportunities
If the cause of death appears obvious (like an MVC) why would an autopsy be performed?
To avoid or refute allegations made at a later date
Non-ionizing radiation has a cumulative effect and these body parts are most susceptible
lymph/bone marrow with early -penias
testes and ovaries causing destruction of gametes
What age group is at the highest risk of death by Homicide?
15-34
may be related to race/SES
How do we document cause of death on a death certificate?
(Example case)
mechanism COD: Massive Hemorrhage
due to
proximate COD: Gun shot wound to chest
Manner of death: Homicide
In what situation would cause of death be unknown?
In what situation would manner of death be undetermined?
Autopsies are structural analyses not functional ones, so could miss something physiological
Suspicious of foul play but missing facts/evidence to make a claim
What manner of death is SIDS?
In a possible SIDS case, baby should be examined by ME and if there is no evidence of foul play or unexpected cause of death, listed as SIDS, Natural Death
How can we tell who was driver/passenger in a case of a car accident based on dicing injuries?
Driver will have dicing injuries from window glass on left side of face/body and passenger will have dicing injuries on right side of face/body
(in an ideal case and in a country with driver on the left)
What is overkill phenomenon?
lots of stabs/injuries typically from someone close to victim/crime of passion
What is a hesitation wound?
like a “practice” wound, often from an inexperienced killer not sure how to inflict the fatal injury
What are examples of defensive wounds?
Lacerations/contusions on hands, forearms, etc from attempting to block an injury
What are some typical suicide injuries?
Wrist/neck lacerations
may have suicide note
How does a high speed bullet cause tissue damage?
causes cavitary changes greater in size in the middle of the tissue rather than the entry/exit wound
all of that damaged tissue needs to be debrided to avoid necrosis/infection
What is one way to match a bullet with the type of weapon it came from?
Rifling pattern is weapon specific (not present on smooth bore/shot guns)
