Forensic Pathology

DNA…the Indispensible Tool

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" 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 In the 17th Century, a system known as vitae

dubiae 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 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" 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 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 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 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:

1. Natural- natural occurrences, these make up over 50% of all deaths the ME sees

2. Accidental- occur from unplanned and unforseen events, example: car accident

3. Suicidal- caused by the dead person’s own hands4. Homicidal- occur as the result of another person

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 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 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 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? 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? 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 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? A decaying body will keep up to five days in a

refrigerated vault without losing valuable structure and rigidity

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 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 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 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

Diagram of Bullet Path

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:

1. Making the Incision 2. Removing the Heart and Lungs 3. Examine the Abdomen 4. Collecting Samples5. Assessing the Head and Brain6. Returning the Organs and Suturing

Make the Y Incision

Made on the Ventral Side of the bodyThree arms on the incision –

Two extending from each clavicle to the sternum (shoulder to breastbone)The third follows the mid-line down to the pubisThe ribs and clavicles are now cut with a saw or shears and the breastplate is removed

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

HeartAortaInferior vena cava

Examine the Abdomen

Each organ is weighed and measuredTissue samples are taken from each organ for testing

Collect Samples

Stomach contents are examined for toxicological evidence, also can determine time of last mealAlso will take samples of ocular fluid, bile from the gall bladder, urine, and liver tissue

Assessing the Head and Brain

Look for skull fractures and head trauma before removing brainTriangular section of skull removed above eyes and brain is observed in situ (in place) before being removedAfter removal, ME has a very short time frame for examining the brain before it turns to mush

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?

Determine if the bones are humanThe front paw bones of a bear are very similar to the human handShell fragments from turtles can be mistaken for human skull fragmentsSheep ribs are similar to human ribsInfants 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 foundA 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

Skeletons…

Determine AgeMore 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 ageSkull – not of any use in adults, but in infants, one can determine age based on fusing of suture lines in the skull fragmentsLegs and Arms – determine age of 25 or younger, bones have reached max growth by that agePelvis – stops growing at age 50Ribs – 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

Skeletons…

Determine StatureIf a full skeleton is found, this job is easy. Sadly, a full skeleton is rarely ever foundHeight 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

Skeletons…

Determine Sex –In infants this is nearly impossibleIn 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 malesThe female pelvis is wider and the pelvic outlet is more open, for childbirth purposesThe male pelvis is designed only for support and movement, thus it is thicker and the pelvic outlet is much more narrowThe male mandible ( jaw bone) is slightly curved and in females, it is straightThe male skull has more prominent crest and ridges and is much thicker and larger

Skeltons…

Determine RaceSkulls

Caucasians – have high rounded skulls, straight faces, and narrow protruding noses, triangular eye socketsNegroid – lower and narrower skulls, wider and flatter noses, prominent and protruding teeth, squared eye socketsMongoloids – broad round skulls, arched face, round eye sockets, wide facial dimensionsMixed Race – can not be determined due to mix of features

Determining TOD

Examine artifacts from burial siteChemical 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 aminosUV Light Test – fresh bones glow when exposed to UV light, bones 100 years old or older do not glow at allRadioactive Dating – Not of any major use in forensics due to gaps in accuracy

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 body8-12 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

A victim who ran from an assailant will show stiffening in the legs firstPoisoned victims become stiff instantly due to nervous system reaction to poisonElevated body temperature prior to death speeds up the rigor mortis process

Lividity…Getting the Blues

Livor Mortis or Postmortem HypostasisStagnation of the blood in the vessels due to the stopping of blood flow and pooling where gravity takes itAny part of the body that presses against a firm surface is pale and the surrounding areas are lividAppears about 30 minutes after death and reaches maximum at 8-12 hours after deathColor indicates condition

Red/Pink – high oxygen levelsDeep purple – severe heart failureGray - poison

Putrefication

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…

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 presentWithin three days, they are ½ inch in length After 12 days, the maggots have fully developed and the process continues

More Bugs

Generally, if only eggs are present, ME will determine TOD to be within the last 24 hoursExceptions:

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