foresnsic pathology Flashcards
pathology
science of the cause and effect of diseases
pathologist
medical doctor who studies and diagnoses diseases in people
forensic pathology
science of the cause of disease and trauma that leads to death
forensic pathologist
medical doctor or pathologist who studies the cause of death by examining a corpse
autopsy
standardized dissection of a corpse to determine the cause and manner of death
positive confirmatory identification
objective evidence: fingerprints, dental records (need antemortem sample for reference), DNA, medical prostheses-serialized and barcoded
presumptive identification
reasonable basis of identity
use presumptive methods to narrow down search for a positive ID
mitochondrial DNA, physical attributes (age, sex, hair color), tattoos, scars, birthmarks piercings, family ID, personal belongings
death investigation
purpose is to determine the cause, mechanism, and manner of death
cause of death
injury, disease, or trauma which leads to a person’s death
possibly a sequence of events
most recent is called the mechanism
older conditions lead to most recent
ex: complications during coronary bypass surgery (immediate) as a consequence of a rupture of the heart’s lining due to tissue death from lack of oxygen (proximate) as a consequence of coronary artery disease (proximate)
ex: exanguination (immediate) as a consequence of a gunshot wound to the chest (proximate)
mechanism of death
physiological abnormality that directly results in the death
most recent cause
exsanguination, cardia arrhythmia
manner of death
the way to which the causes of death came to be
explains the circumstances surrounding the death
may describe criminal intent
who is responsible
5 different rulings for manner of death
homicide, suicide, accidental, natural, unknown
manner of initial event determines the ultimate manner of death
death investigator systems
the coroner system, the medical examiner system
up to the state
coroner
generally elected
not required to be a physician
if not physician, must consult with forensic pathologist to perform an autopsy
ME
forensic pathologist
death investigations
determine cause and manner of death
review medical history (could it have contributed?)
determination of injuries that were incurred postmortem
review witness statements (suicidal red flags?)
scene examination (not always practical, use photos to determine postmortem movement, cause of death, time of death)
autopsy
autopsy
seeing with ones own eyes
external/ visual examination (classification of trauma)
internal examination and dissection (hospital and medico-legal
hospital autopsy
conducted based on the doctor’s request
family permission
medico-legal autopsy
medical investigation of death for legal purposes
unexpected/sudden death
unnatural death
suspicious death
external/visual examination
collection and description of any clothing
photographs of body clothed and unclothed
detailed examination of entire body
old wounds and scars
tattoos
more attention to this step in medico-legal vs. hospital autopsy because evidence may be present
sometimes autopsy is dictated
trauma notation in external/visual examination
forms, sketches, photos, measurements
gunshot wounds indicated as exits or entrances
path of bullet through the body
defensive or other wounds
determine they type of wound
size, shape, type
measure dimensions (length, width, depth)
show position relative to anatomical landmarks
defensive wounds
produced when a person attempts to protect themselves from attack
usually involving a knife or sharp object
limitations of identifying trauma to the human body
decomposition
may be difficult to determine type of wound
trauma accelerates decomposition because of insects
body not in original state - alteration
penetration variations
size of wound may not correlate to size of object that created it
classification of trauma
mechanical, thermal, chemical, electrical
mechanical trauma
force is applied to tissue (skin or bone)
body is altered due to force
physical change
types of mechanical trauma
sharp force
blunt force
asphyxia
sharp force trauma
caused by sharp instruments
signifcantly less force needed to cause injury than with a blunt object
identifying sharp force trauma
edges of wound are clean
no tissue bridging (tissue connected between edges of wound)
unusual for skin around wound to be bruised, unless hilt mark of knife
cause/mechanism of death might be exanguination
types of sharp force trauma
incised wounds, stab/puncture wounds, slash wounds, defensive wounds
incised wounds (incisions)
long, not deep, oval, cut, opening, slit, subsurface tissue is exposed
stab/puncture wounds
deep with a lot of length, may be the general shape of the object that made it
may see hilt mark in violent stabbing
size of injury is not always indicative of the size of the instrument
slash wounds
long and superficial
linear not oval
hesitation marks (suicide)
slit throat
defensive wounds
wounds produced when a person attempts to protect themselves from a attack
usually involving knife or sharp object
blunt force trauma
dull or non sharpened objects
baseball bat, brick, bullet, projectile
usually more force necessary than with a sharp force trauma wound
types of blunt force trauma
lacerations, contusions, abrasion, firearm injuries, fracture, rupture of vital organs (internal damage)
lacerations
tears in the tissue
edges aren’t clean
bridging of tissue
contusion (bruise)
accumulation of blood in the tissue under the skin
color changes give a rough estimate of time
assuming person is health
dark blue/ purple in 1-1.8 hrs
blue/brown in 1-2 days
green in 2-3 days
yellow in 3-7 days
abrasion
scraping of skin surface
superficial
fracture
breaking of bones
rupture of vital organs
internal dammage
firearms injuries
projectiles, gases, unburned powder, burned powder
entry wounds smaller and more regular than exit wound
pathway inside body may not be straight
powder burns are close range, show stippling/tattooing, on entry only, powder penetrates skin and cannot be wiped off
contact muzzle imprint (contusion)
contact star shaped laceration (stellate pattern) due to gases
both contacts indicate potential DNA evidence on gun on muzzle and front and inside barrel
due to contact of gun with skin
asphyxia
body deprived of oxygen
result of suffocation (blockage of major airways (nose and mouth)
strangulation (manual or ligature compression of the neck) leaving behind physical evidence
thermal trauma
extreme hot or cold
two types: hypothermia (too much exposure to cold) or hyperthermia (too much exposure to heat, child left in hot car)
burns (rare- usually due to CO poisoning) can sometimes cause massive tissue damage or swelling of airways causing suffocation
chemical trauma
death resulting from interaction of chemicals with the human body
external (acid of alkaline burns)
internal (toxicology)
drugs, cyanide, arsenic
asphyxia (carbon monoxide, body is cherry pink), oxygen in air is replaced by another gas
electrical trauma
electricity can cause ventricular fibrillation
random quivering of the heart that does not properly pump blood through the body
rigor mortis
external/visual examination
stiffening of body after death
calcium buildup
muscles release upon decomposition
onset 2-6 hours after death
release ~24 hours after death
rate depends on antemortem activity and temp
liver mortis
external/visual exam
postmortem lividity
settling of blood due to gravity after the heart no longer circulates it
purplish/bluish discoloration of skin
does not occur where pressure is applied (body lying on back will not show discoloration on area in contact with floor)
can show if a body was moved
petechiae (tardier spots)
external/visual exam
pinpoint hemorrhages found around eyes, lining of mouth, and throat
hanging/strangulation victims
tiny blood vessels have burst due to pressure
specimens taken during external/visual exam
ligatures (leave any knots intact and cut around knot)
trace on clothing or body
dna on body (blood, saliva, semen)
for DNA analysis: pulled head hairs with root and fingernail clippings
for trace analysis: other hairs (eyelashes, pubic, eyebrows) and GSR (stubs of hands)
internal exam and dissection
opening chest to examine internal organs
removed, weighed, and dissected to determine disease or injury
skull sawed to remove brain and examine
specimens taken for analytical testing
blood samples, urine from bladder, stomach contents, diseased or injured tissue
time of death
external exam changes
temperature (algor mortis), livro, rigor, decomp
chemical changes in body fluids
digestion (stomach contents)
survival after injuries (blood loss)
difficult, imprecise, more inaccurate as postmortem interval increases
decomposition
fresh, bloated, decay, dry
depend largely on environment
geographical location, season, clothing, sun exposure, insect/animal activity
histology
tissue samples taken to determine disease, trauma, pre-existing ocnditions
toxicology
presence of drugs, ethanol, CO or other toxins in human tissue or fluids
help determine if these were factors in COD
