1. Forensic Pathology
- postmortem investigation of sudden or unexpected death or trauma to the living
Greek: pathos – disease logos – study of
Pathologist is a medical doctor (10-15 post secondary training), detective, public relations – much time spent communicating findings to law enforcement officers and/or jury

2. Role of the Forensic Pathologist
4 broad determinations to be made:
Cause of Death – medical diagnosis (the injury)
Mechanism of Death –how the injury produced death (arrhythmia, exsanguination)
Manner of Death
1. Homicide 2. Suicide 3. Accidental 4. Natural Causes
D. Time of Death
Cause of Death
- Proximate cause of death – initial injury that leads to sequence of events which cause death
- Immediate cause of death – injury/disease that finally kills person
Example: Man burned in house fire dies weeks later due to sepsis (infection)
proximate: burns immediate: sepsis
B. Cause could be gunshot wound, Mechanism might be blood loss
C. 2. Suicide – not always easy (hanging with erotic literature), insurance does not pay so recorded manner of death is important
3. Accidental – may involve human negligence
4. Natural – disease or old age

3. Time of Death Can estimate time of death from body changes
estimate: [98.6 oF – rectal temp]/1.5
insect action (forensic entomology)
stomach contents (stage of digestion)
last known activity (last sighting, newspaper/mail)

4. The Body Farm
1 acre of land owned by the University of Tennessee

5. Normal Postmortem Changes
Algor mortis: body cooling
Rigor mortis: body stiffening
Livor mortis: (lividity) blood settling
Putrefaction: destruction of body tissue by bacteria

6. Algor mortis Cooling of the body after death.
Best indicator of TOD in 1st 24 hrs
Taken:
Rectal
Liver

7. Algor mortis Body cools approx 1.5 degrees C/hr
Skinny cools faster
No clothes cools faster
In water cools much faster
normal temp–measured temp/ 1.5 = # hrs

8. Rigor Mortis Rigor: stiffening of muscles due to build up of salts.
Begins: 12 hours post mortem
face, arms, abdomen, legs
Takes: 12 hours to get fully stiffened
Then starts to go away in same order
Face, arms, abdomen, legs

9. Rigor Begins: 12 hours post mortem
face, arms, abdomen, legs
Takes: 12 hours to get fully stiffened
Then starts to go away in same order
Face, arms, abdomen, legs

10. Rigor Mortis Body warm not stiff less than 3 hours
Stiffening of muscles seconds or minutes after death
Rigor mortis results when [ATP] concentrations fall
ATP = relaxed muscles
Rigor mortis stops when muscles begin to decompose ~ 36 hours after death
Body warm not stiff less than 3 hours
Body warm stiff hours
Body cool stiff hours
Body cool not stiff more than 36 hours

11. Livor Mortis Lividity: red/purple coloration of skin.
Due to settling of blood after death
Skin will appear white in areas that were compressed.

12. Lividity will appear in about 2 hours.
Areas will turn white if you press
Lividity will be “set” after 5 hours

13. Normal Postmortem Changes
Algor Mortis
Rigor mortis
Livor mortis
Putrefaction
Desiccation – mucous membranes (lips, eyes) shrivel and look darkly colored
- time depends on location of the body, environmental conditions
Putrefaction – (A) greenish discoloration of skin (B) growth of bacteria unchecked by immune system causes gas production which may swell, rupture organs or make soft tissue appear swollen
- time again depends on environment of body (few days to weeks if colder)
Autolysis – cells begin to break open and ooze contents
- liquefaction of soft tissues
Proteins break down into amino acids which are further degraded by bacteria into “biogenic amines” - this is what smells (putrescine, cadaverine)

14. Decomposition 2 days post mortem Marbling neck and shoulders
1st red then green
From bacteria getting into subQ tissue
bloating from gases created by bact.
Organs decompose in order:
Stomach and intestines, heart and liver
Musculature

15. Trauma to the Human Body
Role of the Pathologist
Determine type of wound
Measure the dimensions (length, width, depth)
Position relative to anatomical landmarks
Determine initial location if wound involves cutting, slashing, etc.
Determine height from heel
We said role of pathologist is to determine cause of death, extent of injuries to living, disease vs. poisoning, possible time of action:
To determine these, pathologist will perform an autopsy (we’ll look at this in a couple minutes)
First lets look at common types of trauma often encountered
Why a pathologist looks at trauma above….

16. Types of Wounds (Trauma)
Lacerations
Incised Wound
Puncture
Abrasion
Contusion
Gunshot

17. Lacerations Tearing injury due to friction or impact with blunt object
Edges are ragged, bruised, abraded

18. Incised Wounds Slash Stab Incised Wounds
Cutting injury associated with a blade having smooth edges
Slash – longer than it is deep
Stab – depth greater than length
Puncture
Penetrating injury due to pointed object with no blade – icepick, pencil, etc

19. Abrasions
Abrasion
Friction injury removing skin or tissue

20. Contusions
Color changes a bruise goes through can give rough estimate of time of injury
Dark blue/purple (1-18 hours)
Blue/brown (~1 to 2days)
Green (~ 2 to 3 days)
Yellow (~3 to 7 days)
Assumes person is healthy.
Contusions
Bruise due to rupture of small blood vessels (skin or internal organs)
Colors result from breakdown of hemoglobin from tissues

21. Stab Wounds
Laceration is a tearing injury due to friction or impact with a blunt object.
Puncture is a penetrating injury due to pointed object without a blade, such as an ice pick
Serrated blades produce the same smooth edges as nonserrated blades.
Abrasion is a friction injury removing superficial layers of skin,
Contusion is a bruise due to rupture of small blood vessels.
Slash wounds tend to look like bullet wounds that only graze the surface of the skin. Other types of slash wounds are called "hesitation marks" commonly found in suicide cases. They are typically rectangular in shape; i.e., their cuts are as wide and they are long.
Incision wounds: cutting with a blade, always have lengths greater than their depth

22. Gunshot Wounds Things for pathologist to learn: type of firearm
distance of gun to victim
entrance vs exit wounds
track of projectile
Track of projectile – cause of death (hit certain organs?), location of shooter

23. Gunshot Wounds
Stippling – powder burns on the skin when the gun is inches to a few feet from the victim
Track of projectile – cause of death (hit certain organs?), location of shooter
Starring of a contact wound – barrel touching the skin

24. Gunshot wounds Contact Wound: Muzzle applied to skin at shooting.
Impression of muzzle burned around entrance wound
Close Range (6-8 inches): Stippling
Intermediate Range (1- 3 ft.): hot fragments of burning gunpowder; “ball”
Distant (greater than 3 ft.): No soot or burning of wound margins
Entrance wound: surrounding skin dragged in
Exit wound: skin pushed out

25. Close range Close Range
(6-8 inches): Entrance surrounded by stippling- HOT soot traveling for short distance; BURNS

26. Intermediate range
Intermediate range
1-3 feet
Gunpowder “ball”

28. POISONING Determined by discolorations on body
Cherry- red lividity is sign of carbon monoxide poisoning
Toxins give off unusual odors
Certainty of diagnosis requires toxicological confirmation
Samples taken of stomach, vomit, kidney, lungs, liver

29. BURN Wounds caused by heat, chemicals, or electricity
Scorching or burning of skin leads to sepsis and is immediate cause of death
Wounds caused by heat, chemicals, or electricity
Fire victims found in “pugilistic” position: clenched fists, resembling pose of boxer
Heat causes protein in body to contract
Blood and lung samples taken

30. Blunt force trauma
Blunt Force trauma results from clubbing, kicking, or hitting the victims.
The blow produces a crushing effect on the human body, resulting in contusions, abrasions, lacerations, fractures, or rupture of vital organs.
Red-blue contusions are always present, but this varies by the weight of the individual (obese people bruise easier than lean people)