Transcript Document

POST
MORTEM
CHANGES
DEATH INVESTIGATION
The Coroner System dates back
to feudal England. It is the most
common system within the United
States as far as dealing with
determination of death, and any
legal/forensic ramifications
associated with death.
CAUSE OF DEATH
(COD)
One of the major determinations made in forensic
pathology is the Cause of Death (CoD).
CoD is defined as the injury or disease producing a
physiologic derangement in the body that results
in the individuals’ death.
The immediate CoD is different than the proximate
CoD.
As an example – if someone is shot on Monday,
and dies from a shooting-related infection 2 weeks
later, the shooting would be listed as the proximate
CoD, and the infection as the immediate CoD.
MECHANISM OF
DEATH
Correlated with the Cod is the Mechanism
of Death.
The Mechanism of Death is the physiologic
derangement/s produced by the CoD, thus
resulting in death.
MANNER OF DEATH
(MOD)
The Manner of Death (MoD) is, perhaps, the most
important determination made – at least from a legal
point of view.
The MoD explains how the cause of death came about.
Mod falls into one of the following five categories:
1.
natural
2.
accident
3.
suicide
4.
homicide
5.
undetermined
AUTOPSY
Either Medical or Forensic
Medical autopsies are done to determine the
medical reason a person died,
• i.e., congestive heart failure, myocardial infarction,
non-specific cardiomyopathy, etc.
• From the point of view of a death certificate –
all of these would be classified as "natural
causes" in terms of MoD.
• The following are some typical situations in
which an autopsy would likely be performed:
When do they Autopsy
Each specific case has characteristics that will determine whether
an autopsy is actually done, however.
violent deaths/accidents
• suicides
• homicides.
Suspicious deaths
• unexpected deaths
• unattended deaths
• deaths in custody (always done)
THE AUTOPSY
External Exam (clothing, exterier of the body)
Internal Exam (The surgical portion)
• Samples are taken
• Major organs are sampled, with emphasis given to brain, liver,
kidneys, and adipose.
• blood, urine, CSF, and intra-ocular fluids (aqueous & vitreous)
(based on TOD)
Y INCISION
WHAT HAPPENS TO
THE SAMPLES?
Toxicology
• Tox screens are done as "panels" (e.g., an opioid panel, or an
amphetamine panel, or cannabis, or......) - and only the
specific drugs that are in that particular panel can be tested
for.
• There are many toxins/poisons that simply aren’t on any
standard tox panel and, therefore, would not show up on a
standard tox screening.
• Also - poisoning can be done with ELEVATED levels of
naturally occurring chemicals!
POISONING
DETERMINATION OF
TIME OF DEATH (TOD)
Time of death (ToD) is most often used
when talking about a death that has
occurred within a relatively recent time
frame – the last day or two. As the window
of time increases, a better term is Post
Mortem Interval, or PMI.
ALGOR MORTIS
Post-mortem cooling. Once a person dies, cellular
metabolism ceases and, therefore, the production of heat.
i.e., it is not as accurate as the writers of
television forensic shows might have you
believe. And, once the body has reach ambient
temperature, it is of no significant value.
(98.4° - rectal temp) / 1.5 = hours since death
• This is a rough calculation effected by many variables
HEAT LOSS
MECHANISMS
conduction - transfer of heat by direct contact with
another object
radiation - transfer of heat to surrounding air &
objects by infrared waves
convection - transfer of heat through moving air
currents adjacent to the body
evaporation – loss of heat due to the conversion of
water from the liquid phase to the gaseous phase.
FACTORS THAT
INFLUENCE HEAT LOSS.
Temperature gradient
Air movement(convection)
Clothing
Body fat
Surface area
environment
LIVOR MORTIS
The settling of blood in dependent tissues of the
body.
Usually starting within the first 3-5 hours following death,
and reaching completion by 8 – 12 hours
This discoloration does not occur in the areas of the body
that are in contact with the ground or another object, as the
capillaries are compressed. As the vessel wall become
permeable due to decomposition,blood leaks through them
and stains the tissue. This is the reason for fixation of
hypostasis
If the body is moved prior to fixation of the blood, livor mortis
can "shift" to a new region of the body. Movement of the
body after fixation will not cause a shift in the livor mortis
pattern, and is a good indicator that the body has been
moved.
RIGOR MORTIS
Rigor mortis (or simply rigor) is
commonly known as death rigor,
or the rigidity of death.
RIGOR MORTIS
TIMELINE
THINGS THAT
ACCELERATE RIGOR
MORTIS
prior exercise
seizures
electrocution
hyperpyrexia
hot environment (and the resulting hyperthermia)
acidosis
uremia
RIGOR MORTIS CAN BE
DELAYED BY THE
FOLLOWING:
cold environment
hypothermia
decreased muscle mass
carbon monoxide (CO) exposure
Therefore, anything that makes the
tissue warmer or more acidic will tend to
shorten the time line for onset, where as
cooling or preventing elevated H+ will
lengthen it.
DECOMPOSITION &
PUTREFACTION
Decomposition simply refers to
the breakdown of something – in
this case, of the tissues of the
human body.
APPEARANCE OF THE
EYES
If the eyes remain open at time of death they will become
cloudy within 2-3 hours.
If the eyes are closed after death, then the change will take
longer (approximately 24 hours)
STOMACH CONTENTS
Undigested stomach contents
Death occurred 1-2 hours after
meal
Stomach empty
Death occurred 4-6 hours after the
meal
Small intestines empty
Death occurred 12+ hours after
meal.
GUN SHOT WOUNDS
ENTRY WOUNDS
EXIT WOUNDS
STRANGULATION
KNIFE WOUNDS
DROWNING VICTIMS
ELECTROCUTION
BITE MARKS