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Forensic Pathology. DNA…the Indispensible Tool. Scenario to Ponder …. The time period…19 th Century The stethoscope had not been invented You are buried alive because you have a weak heartbeat As you wake up from passing out, you find a grave digger above you throwing on the dirt

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forensic pathology

Forensic Pathology

DNA…the Indispensible Tool

scenario to ponder
Scenario to Ponder…
  • The time period…19th Century
  • The stethoscope had not been invented
  • You are buried alive because you have a weak heartbeat
  • As you wake up from passing out, you find a grave digger above you throwing on the dirt
  • In the 19th century, there was no definitive way of determining if a person was dead
defining dead
Defining "Dead"
  • In the late 16th century, a list of tests were devised to determine if someone was dead:
      • Tongue and Nipple Pulling
      • Tobacco and Smoke Enemas
      • Insertion of Hot Pokers into Body orifices
the waiting mortuary
The Waiting Mortuary
  • In the 17th Century, a system known as vitaedubiae asylums
  • These places of holding bodies thought to be dead was quite the improvement from having hot pokers shoved in your orifices
  • The suspected dead were placed on cots and watched until decay set in
  • Although this process was very difficult for families, there was a huge reduction in the number of premature burials
the invention of the stethoscope
The Invention of the Stethoscope
  • This was the first of many steps in easing the determination of death
    • Electrocardiogram (EKG) – device that records electrical impulses from the heart, was invented shortly after the stethoscope
    • 20th Century, the advent of cardiopulmonary resuscitation (CPR) followed by the use of ventilators and pacemakers which all promote heart function after death muddied the water again
      • This brought about the concept of Brain Dead, which simply means that the brain is not functioning, but the heart is still beating
current definition of dead
Current definition of "Dead"
  • Someone who has a heartbeat or a pacemaker and is on a ventilator requires the absence of electrical activity in the brain OR determination of loss of blood flow
  • Before a doctor “pulls the plug”, he/she must ensure that there is a 0% chance of survival. Otherwise the doctor can be held responsible for the death
important terms
Important Terms
  • Cause of Death – the reason a person died
    • Abnormal physiological changes that lead to death
    • Examples: heart attack, gunshot wound, skull fracture
  • Mechanism of Death- the result of the cause of death
    • Examples: exsanguinations (bleeding to death), sepsis (infection in the blood stream), cerebral contusion (direct trauma to the brain), subdural or epidural hematoma (bleeding around the brain), asphyxia (stopped breathing)
cause v mechanism
Cause v. Mechanism
  • One cause can lead to multiple mechanisms
    • Example: bleeding to death (cause of death) results from a gunshot wound, stabbing, bleeding ulcer, bleeding lung tumor, etc.
cause of death unknown
Cause of Death…Unknown
  • This is grounds for an Autopsy from a medical examiner or a coroner
  • It is the job of the medical examiner to determine which of the four manners of death are at play:
    • Natural- natural occurrences, these make up over 50% of all deaths the ME sees
    • Accidental- occur from unplanned and unforseen events, example: car accident
    • Suicidal- caused by the dead person’s own hands
    • Homicidal- occur as the result of another person
the fifth manner of death
The fifth Manner of Death
  • In the event where the ME can not determine the cause of death, the death is classified as undetermined or unclassified
pathology as a science
Pathology as a Science
  • Pathology is the study of diseases and their effects on the body
  • Dates back as far as the 1800s
  • By the mid-twentieth century, many sub-branches of pathology began erupting
    • Forensic Pathology became a recognized branch in 1959
      • FP is the study of medicine and how it applies to the law, in particular criminal law
      • More than 50% of cases seen deal with disease
      • Performs autopsies that provide evidence to court
becoming a fp
Becoming a FP
  • 13 years of college, medical school, and on-site training to become a clinical pathologist
  • Serve an additional 1 year fellowship in forensic pathology
  • If you are interested, see me for more details…
forensic v medical autopsy
Forensic v. Medical Autopsy
  • Forensic Autopsy: performed for legal documentation and affirmation
  • Medical Autopsy: performed at the hospital to determine any unknown diseases associated with the deceased
who gets an autopsy
Who Gets an Autopsy?
  • ME will autopsy anyone who dies:
    • Traumatically- occurring from accidental, homicidal, or self-inflicted injury
    • Unusual- unnatural or suspicious circumstances
    • Sudden- within a few hours of onset of symptoms
    • Unexpected- occurring in someone who was not thought to be ill
physician is uncomfortable now what
Physician is uncomfortable…now what?
  • If the physician requests an autopsy, the case turns into a reportable death or coroner’s case
  • This usually occurs when death falls into one of these categories:
      • Violent deaths
      • Deaths in the workplace
      • Sudden, unexpected, or suspicious
      • Deaths during incarceration
      • Deaths unattended by a physician or medical staff
      • Deaths during medical procedures
      • Deaths during an abortion
      • A found body
performing an autopsy
Performing an Autopsy
  • Designed to determine how, when , and why someone died
  • Everything from debris under fingernails to the contents of the deceased’s stomach could lend clues to those three questions
how long does it take
How long does it take?
  • A decaying body will keep up to five days in a refrigerated vault without losing valuable structure and rigidity
external examination
External Examination
  • Measuring and weighing- this is the first step of the autopsy. Consists of height, weight, age, sex, race, hair color and eye color
  • Photograph the Body- both clothed and unclothed, frontal and profile pictures are taken, every scar, birthmark, tattoo, and unusual physical feature is noted
  • Examine clothing- search for trace evidence, damaged to clothing (may correspond to injury to the body)
external examination1
External Examination
  • Establish TOD- determine rigor mortis and lividity (settling of the blood)
  • Take X-Ray’s- not used in every autopsy, especially important in gunshot cases
  • Look for Trace Evidence- the body is examined intensely to find any foreign material, this is the most painstaking step in the autopsy
  • Examine Injuries- each abrasion or bruise is documented on a diagram using at least two reference points
common injuries
Common Injuries
  • Lacerations – cuts and slices, these are photographed and measured both lengthwise and depth, a search for tool fragments is also conducted
  • Contusions – bruises, measured and photographed
  • Widespread lacerations and contusions indicate a struggle occurred
  • Multiple wounds on the arm indicate a defensive battle
  • In some cases, an accurate count of the number of wounds is impossible to count, in that case the ME will estimate the minimum number of wounds needed to make the kill
more common injuries
More Common Injuries
  • Hesitation Wounds – often accompanying a suicide, these are small nicks around the fatal wound, these are indicative of someone gathering enough courage to make the final cut
  • Gunshot wounds – photographed, measured, and X-rayed, the X-ray plots the path of the bullet and shows its final resting place

X-ray of Governor Connally’s Wrist

dissecting the body
Dissecting the Body
  • Dissection is the step you see in movies and on TV due to it being the step when the body is actually cut open, this process follows but is not limited to these steps:
    • Making the Incision
    • Removing the Heart and Lungs
    • Examine the Abdomen
    • Collecting Samples
    • Assessing the Head and Brain
    • Returning the Organs and Suturing
make the y incision
Make the Y Incision
  • Made on the Ventral Side of the body
  • Three arms on the incision –
    • Two extending from each clavicle to the sternum (shoulder to breastbone)
    • The third follows the mid-line down to the pubis
    • The ribs and clavicles are now cut with a saw or shears and the breastplate is removed
remove the heart and lungs
Remove the Heart and Lungs
  • May be removed sequentially, but are most often en bloc (as one unit)
  • Blood samples used in typing, DNA analysis and other uses is taken from
    • Heart
    • Aorta
    • Inferior vena cava
examine the abdomen
Examine the Abdomen
  • Each organ is weighed and measured
  • Tissue samples are taken from each organ for testing
collect samples
Collect Samples
  • Stomach contents are examined for toxicological evidence, also can determine time of last meal
  • Also will take samples of ocular fluid, bile from the gall bladder, urine, and liver tissue
assessing the head and brain
Assessing the Head and Brain
  • Look for skull fractures and head trauma before removing brain
  • Triangular section of skull removed above eyes and brain is observed in situ (in place) before being removed
  • After removal, ME has a very short time frame for examining the brain before it turns to mush
return the organs and suture
Return the Organs and Suture
  • After all needed samples are taken, the body is sutured and returned to the family for burial
so they only found a skeleton now what do you do
So, they only found a skeleton…Now What do you do?
  • Determine if the bones are human
    • The front paw bones of a bear are very similar to the human hand
    • Shell fragments from turtles can be mistaken for human skull fragments
    • Sheep ribs are similar to human ribs
    • Infants are almost impossible to identify since the bones are much smaller (confused with small animals) and the skull is not yet fused so a full skull will not be found
    • A forensic Anthropologist uses the fact that bones have ridges, indentions, and bumps that are indicative of particular species and function
      • These traits are used to identify species
  • Determine Age
    • More accurate for younger victims than older victims
      • Why is this?
    • Look for:
      • Teeth – used to identify someone 18 years or younger, since all teeth are typically in place by that age
      • Skull – not of any use in adults, but in infants, one can determine age based on fusing of suture lines in the skull fragments
      • Legs and Arms – determine age of 25 or younger, bones have reached max growth by that age
      • Pelvis – stops growing at age 50
      • Ribs – can determine age up to 70 years ( ±1.5 years up to 30 years old and ±5 years up to 70 years old)
      • Bone Density – less dense means older person
  • Determine Stature
    • If a full skeleton is found, this job is easy. Sadly, a full skeleton is rarely ever found
    • Height is usually 5 times the length of the humerus (upper arm bone)
    • Thickness of bone is proportional to muscle structure
      • Also can be indicative of dexterity, right handed people have thicker bones on the right side of the body
  • Determine Sex –
    • In infants this is nearly impossible
    • In adults or teens, puberty has set bones into gender specific patterns
      • In males, the humerus, the radius (the lower bone in the thumb), and the femur are larger in males
      • The female pelvis is wider and the pelvic outlet is more open, for childbirth purposes
      • The male pelvis is designed only for support and movement, thus it is thicker and the pelvic outlet is much more narrow
      • The male mandible ( jaw bone) is slightly curved and in females, it is straight
      • The male skull has more prominent crest and ridges and is much thicker and larger
  • Determine Race
    • Skulls
      • Caucasians – have high rounded skulls, straight faces, and narrow protruding noses, triangular eye sockets
      • Negroid – lower and narrower skulls, wider and flatter noses, prominent and protruding teeth, squared eye sockets
      • Mongoloids – broad round skulls, arched face, round eye sockets, wide facial dimensions
      • Mixed Race – can not be determined due to mix of features
determining tod
Determining TOD
  • Examine artifacts from burial site
  • Chemical Analysis – measure nitrogen levels in the bones, Nitrogen decreases as time passes; Also look for amino acids, bones that are fresh may yield 15 aminos and old bones give off only 7 aminos
  • UV Light Test – fresh bones glow when exposed to UV light, bones 100 years old or older do not glow at all
  • Radioactive Dating – Not of any major use in forensics due to gaps in accuracy
rigor mortis
Rigor Mortis
  • Stiffening of the muscles in the body following this time scale:
    • 2 hours: small muscles in the face and neck stiffen and the progress heads to the lower body
    • 8-12 hours: body is completely stiff and in position at time of death unless body is altered posthumously
    • 30 hours: the body loosens again as blood begins to pool, this period of stiffness is called the rigid state
      • The relaxed state after 30 hours is called flaccid state
exceptions to the rigor mortis rules
Exceptions to the Rigor Mortis Rules
  • A victim who ran from an assailant will show stiffening in the legs first
  • Poisoned victims become stiff instantly due to nervous system reaction to poison
  • Elevated body temperature prior to death speeds up the rigor mortis process
lividity getting the blues
Lividity…Getting the Blues
  • Livor Mortis or Postmortem Hypostasis
    • Stagnation of the blood in the vessels due to the stopping of blood flow and pooling where gravity takes it
    • Any part of the body that presses against a firm surface is pale and the surrounding areas are livid
    • Appears about 30 minutes after death and reaches maximum at 8-12 hours after death
    • Color indicates condition
      • Red/Pink – high oxygen levels
      • Deep purple – severe heart failure
      • Gray - poison
  • The takeover of bacteria beginning the decomposition process
    • Mummification – occurs when body dries out due to high temperatures or concentration gradient (Egyptians using salt)
    • Adipocere Formation – formation of a waxy substance due to influx of water (grave wax), it takes three to six months to form
      • When sinkers become floaters:
        • Rise to surface due to gas buildup from decomposition of body tissues
          • In warm water the time of flotation takes much less time than cooler water
getting buggy
Getting Buggy…
  • Blowflies – show up within the first hour after death to lay eggs in the nose, armpit, groin, mouth, and open wounds
    • Within 24 hours, the eggs hatch and maggots are present
    • Within three days, they are ½ inch in length
    • After 12 days, the maggots have fully developed and the process continues
more bugs
More Bugs
  • Generally, if only eggs are present, ME will determine TOD to be within the last 24 hours
  • Exceptions:
    • Blowflies do not lay eggs at night and are less abundant during winter months
      • This as well as maggots being dormant during cold spells and timing being key makes TOD determination difficult is the killer has read up on his entomology