Forensic Pathology
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Transcript of Forensic Pathology
Students Will Be Able To:• Discuss the definition of death.• Distinguish between four manners of
death: natural, accidental, suicidal, and homicidal.
• Distinguish between cause, manner, and mechanisms of death.
Death• Is the cessation of end of life
• Irreversible cessation of circulation of blood
• Irreversible cessation of all brain activity
Death• First stage of death is stoppage
• Heart stops beating• Cells die because of no oxygen
• Known as autolysis• Cells breakdown resulting in cell
membrane dissolving and cell contents spilling out
• Nerves, muscles, organs, and brain stop working
Job Duties• A medical examiner has 5 job duties
• Identify the decedent• Determine the manner of death• Determine cause of death• Determine the mechanism of death• Determine time of death
• Manner, cause, mechanism, and time of death determined during autopsy
Identification of the Decedent• To facilitate identification of a corpse, the
following procedures are standard:• Physical Description • Scars and Marks• Fingerprints• Photographs• Age Determination—use of teeth for rough
estimate• Dental Features• Radiological Evidence• Blood factors• Medical Indications• Other means
Manner of Death• Is the way that a person dies• There are five manners of death
• Natural• Accidental• Homicidal• Suicidal• Undetermined
• Autopsy findings are critical in determining the intent or mode of death
Natural Death• Death by natural cause is a term used
by coroners to describe the death of someone by occurring disease process, or is not apparent given medical history or circumstances
• The majority of natural death is caused by old age
• Other causes of natural death are heart disease, stroke, genetic disorders, etc.
Accidental Death• Accidental death is a death that is often
caused by mistake or in a freak occurrence
• These deaths are not planned yet can be explained by surrounding circumstances
Homicide• The term ‘homicide’ refers to the act of
killing another person• Homicide is often the most investigated
death, therefore making it the most autopsied
Suicide• The act of ending ones own life • These autopsies often easily identify
source, cause, and other factors of the death
• Suicide is often identified in the forensic autopsy as a cause of toxic, firearms, blunt force trauma, etc
Undetermined Death• In some jurisdictions, the
Undetermined category may include deaths in absentia, such as deaths at sea and missing persons declared dead in a court of law; in others, such deaths are classified under "Other"
Manner of Death• Consider the following two examples.
How would you categorize the manner of death?• A man with a heart condition is
attacked and dies from a heart attack during the assault. Is the manner of death accident or homicide?
• An elderly woman dies after being kept from receiving proper health care by her son. Is the manner of death natural or homicide?
Cause of Death• The pathological condition that
produced death• Ex: bludgeoning, shooting, burning,
drowning, strangulation, suffocation, hanging, drowning
Mechanism of Death• Describes the specific change in the
body that brought about the cessation of life• Ex: loss of blood, exsanguination,
cessation of brain function
Students Will Be Able To:• Explain how the development of rigor,
algor, and livor mortis occurs following death.
• Use evidence of rigor, algor, and livor mortis to calculate the approximate time of death.
• Use evidence from the autopsy’s report on stomach contents to estimate time of death.
Time of Death• Generally, time of death is estimated
from certain changes that occur in the body following death
• Changes can also indicate alterations in the body’s position after death and whether or not the death was murder or suicide
Time of Death• Can use the following to estimate time
of death• Liver mortis• Rigor mortis• Algor mortis• Stomach content• Ocular changes
Livor Mortis• Means death color• As the body decomposes, blood seeps through
tissues and settles in the lower parts of the body
• RBC’s break down causing hemoglobin to spill out• Hemoglobin turns purple when autolysis
occurs• Dark purplish-blue discoloration that is seen
on the portions of the body nearest the ground is called postmortem lividity
Livor Mortis• Provide clues as to how long a person has
been dead• Lividity begins 2 hours after death• After 8 hours, lividity is fixed
• Discoloration becomes permanent• If death occurred between 2 and 8 hours,
lividity will be present but when the skin is pressed, the color will disappear
• Also provides a clue as to what position a person was in when they died• Lets CSI’s know if the body has been moved
Livor Mortis• Ambient temperature at which a person
dies impacts the time it takes for lividity to set in• If outside on a hot day, livor mortis
occurs at a faster rate• If in a cool place, livor mortis occurs
at a slower rate• Also affected by anything impeding
blood flow such as watches, rings, belts, etc
Rigor Mortis• Immediately after death the body is limp due
to relaxation of the muscles• Over time the muscles begin to stiffen due to
chemical changes within the muscle tissue—this is called rigor mortis• Calcium accumulates in the muscle tissue
resulting in muscle fibers remaining in a contracted, rigid position
• Rigor begins at the lower jaw and neck and spreads downward
Rigor Mortis• Starts within 2 hours after death
• Starts in head• After 12 hours, the body is at its most
rigid state• Stiffness disappears after 36 hours
• Can last as long as 48 hours• Depends on body weight and
temperature
Rigor Mortis• No visible rigor entails that the
individual has been dead less than 2 hours
• If body is rigid, then the body has been dead 12 hours
• If rigor is only in head, then the person has been dead a little over 2 hours
• If there is rigor throughout the body but not in the face, then the body is losing rigor resulting in the individual being dead over 15 hours
Rigor Mortis• Factors affecting rigor mortis include
• Ambient temperature• Cooler the body, the slower the onset of rigor• Warmer the body, the faster the onset of rigor
• Person’s weight• Rigor is slower in a heavier person than in a
thinner person• Due to stored oxygen
• Type of clothing• Presence of clothes accelerates rigor mortis• Naked body cools faster which slows down
rigor
Rigor Mortis• Factors affecting rigor mortis include
• Illness• If a person dies with a fever, the body
temperature will be higher and rigor will set in faster
• Level of physical activity before death• If a person was exercising before death,
then rigor will progress faster• Sun exposure
• A body exposed to direct sunlight will be warmer resulting in rigor to occur faster
Algor Mortis• Defined as death heat• Describes the temperature loss in a
corpse• Normal temp is 98.6 F• After death body tends to cool• Generally, temp of a dead body
averages a drop of approx. 1.5 degrees F per hour.
Algor Mortis• To determine the temperature of a
corpse, a thermometer is inserted into the liver
• Generally, temperature of a dead body averages a drop of approx. 0.78°C (1.4°F)
• After 12 hours the body loses about 0.39°C (0.7°F) per hour until the body reaches the same temperature as the surroundings
Algor Mortis• Factors affecting algor mortis
• Surrounding temperature• Body will lose heat faster in a cooler
environment that in a warmer environment• Surrounding air temperature
• Heat loss will occur faster in a windy environment
• Weight of individual• Excess body fat will slow down algor mortis
• Clothing• Presence of clothes will slow down algor
mortis
Stomach Content• Time of death can be approximated by
appearance and amount of stomach contents
• It takes 4-6 hours for the stomach to empty its contents in the small intestine and another 12 hours for the food to leave the small intestine
Stomach Content• If undigested stomach contents are
present, then death occurred 0-2 hours after last meal
• If the stomach is empty, but food is found in the small intestine then death occurred at least 4-6 hours after a meal
• If the small intestine is empty and wastes are found in the large intestine, then death occurred >12 hours after a meal
Ocular Changes• Early postmortem changes occur in the eyes• Buildup of potassium accumulates inside of
vitreous humor of eye• Buildup can be used to estimate the time of
death• If the eyes stay open, a thin film may form on
the corneal surface in a few minutes, and cloudiness in two to three hours
• If the eyes remain closed, corneal film may not occur for hours, and cloudiness may take 24 hrs or longer to appear
Decomposition• Within 2 days after death
• Cell autolysis begins• Green and purplish staining occurs
from blood decomposition• The skin takes on a marbled
appearance• The face becomes discolored
Decomposition• After 4 days
• The skin blisters• The abdomen swells with the gas
carbon dioxide that is released by bacteria living in the intestines
Decomposition• Within 6-10 days
• The corpse bloats with carbon dioxide as bacteria feed on tissues• Eventually the gas causes the
chest and abdominal cavities to burst and collapse
• Fluids begin to leak from the body openings as cell membranes rupture
• Eyeballs and other tissues liquefy• The skin sloughs off
Decomposition• Factors affecting decomposition
• Person’s age• Clothing on body
• Naked bodies decompose faster than clothed bodies
• Size of the body• The fat and fluids in overweight
individuals break down faster than people of normal weight
Decomposition• Factors affecting decomposition
• Environment• Bodies will decompose faster in a
warm environment• Bodies decompose faster in air • Bodies decompose slower in
water or if buried• Nature of death
• Sick individuals decompose faster than healthy individuals
Stages of Decomposition• 5 stages of decomposition
• Initial decay• Corpse appears normal on the outside,
but is starting to decompose from the actions of bacteria and autolysis
• Putrefaction• Odor of decaying flesh is present and
the corpse appears swollen• Black putrefaction
• Very strong odor• Parts of the flesh appear black• Gases escape and the corpse collapses
Stages of Decomposition• 5 stages of decomposition
• Butyric fermentation• Corpse is beginning to dry out• Most of the flesh is gone
• Dry decay• Corpse is almost dry• Further decay is very slow from
lack of moisture
Students Will Be Able To:• Explain the significance of an autopsy.• Describe the steps of an external
examination of the body.• Describe the steps of an internal
examination of the body. • Explain the importance of filling out
paperwork completely during an autopsy.
Autopsy• Preliminary examination
• Conducted in deaths of criminal violence, suicide, accidental deaths, deaths where no physician was present, sudden deaths, prison deaths, and deaths that are suspicious or unusual
• If preliminary examination fails to reveal a clear cause of death—an autopsy is conducted
Autopsy Protocol• The corpse is brought to the medical
examiner’s office in a brand new body bag (to avoid transfer of evidence between cases) or in a set of evidence sheets
• The body is then placed on the cadaver dissection table
Physical Examination• The physical examination of the body is broken
up into two parts• External Examination
• The external examination consists of inspecting the physical outer layer of the body for signs of foul play that would result in injury or death
• Internal Examination• The internal examination consists of
inspecting the internal organs of the body for evidence of trauma or other indications of the cause of death
External Examination• Steps of an external examination• Photographed• Physical evidence collected off body• Samples of hair, nails, etc. are collected• Undressed, examined for wounds• Lacerations, abrasions, bruises
• Measured, weighed, cleaned
Internal Examination• Steps of an internal examination
• Incisions• A “Y” shaped cut from behind
each ear and running down the neck, meeting at the breastbone, continuing towards the groin• Most often used in cases of
suspected strangulation
Internal Examination• Steps of an internal examination
• Incisions• A “T” shaped cut from each
shoulder, meeting at the breastbone, continuing towards the groin.• Used to create a better
looking finished product as this cut is not often seen
• Single vertical cut from throat to groin
• All cuts deviate towards the left
Internal Examination• Cuts
• The chest cavity is cut open using shears
• The ribs are sawed away, letting them be lifted off the body, exposing the heart and lungs
• Removal• All organs are removed
• All removed organs are now weighed and examined for unusual markings or signs
Internal Examination• Brain examination
• An incision is made from a point behind one ear, over the top of the head, to a point behind the opposite ear
• The scalp is pulled away from the skull, creating tow flaps
• The front flap goes over the face, the rear flap over the neck
• The skull is then cut with an electric saw to create a cover that can be pulled off to expose the brain
• The brain is then cut from the spinal cord and lifted out of the skull for further examination
Internal Examination
• The cardiovascular system, the respiratory system, the central nervous system, and all other “systems” in the body that help control activity are examined
Paperwork
• After an autopsy, the medical examiner must fill out paperwork on the deceased and complete a legal death certificate