Forensic Pathology

- postmortem investigation of sudden or unexpected death or

trauma to the living

Role of the Forensic PathologistRole of the Forensic Pathologist

4 broad determinations to be made:

A. Cause of Death – medical diagnosis (the injury)

B. Mechanism of Death –how the injury produced death (arrhythmia, exsanguination)

C. Manner of Death

1. Homicide 2. Suicide 3. Accidental 4. Natural Causes

D. Time of Death

Time of DeathTime 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)

The Body FarmThe Body Farm

1 acre of land owned by the University of Tennessee

Normal Postmortem ChangesNormal Postmortem Changes

1. Algor mortis: body cooling

2. Rigor mortis: body stiffening

3. Livor mortis: (lividity) blood settling

4. Putrefaction: destruction of body tissue by bacteria

Algor mortis• Cooling of the body

after death.• Best indicator of

TOD in 1st 24 hrs• Taken:

– Rectal– Liver

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

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

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

Rigor MortisRigor Mortis

Body warm not stiff less than 3 hours

Body warm stiff 3-8 hours

Body cool stiff 8-36 hours

Body cool not stiff more than 36 hours

Livor Mortis• Lividity: red/purple

coloration of skin.• Due to settling of

blood after death• Skin will appear

white in areas that were compressed.

• Lividity will appear in about 2 hours.– Areas will turn white

if you press• Lividity will be “set”

after 5 hours

Normal Postmortem ChangesNormal Postmortem Changes

1. Algor Mortis

2. Rigor mortis

3. Livor mortis

4. Putrefaction

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

Trauma to the Human BodyTrauma to the Human BodyRole of the Pathologist

1. Determine type of wound

2. Measure the dimensions (length, width, depth)

3. Position relative to anatomical landmarks

4. Determine initial location if wound involves cutting, slashing, etc.

5. Determine height from heel

Types of Wounds (Trauma)Types of Wounds (Trauma)

1. Lacerations

2. Incised Wound

3. Puncture

4. Abrasion

5. Contusion

6. Gunshot

LacerationsLacerations

Incised WoundsIncised Wounds Slash Stab

AbrasionsAbrasions

ContusionsContusions

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.

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

Gunshot WoundsGunshot Wounds

Things for pathologist to learn:• type of firearm

• distance of gun to victim

• entrance vs exit wounds

• track of projectile

Gunshot WoundsGunshot Wounds

Starring of a contact wound – barrel touching the skin

Stippling – powder burns on the skin when the gun is inches to a few feet from the victim

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

Close range• Close Range• (6-8 inches):

Entrance surrounded by stippling- HOT soot traveling for short distance; BURNS

Intermediate range• Intermediate range• 1-3 feet• Gunpowder “ball”

POISONINGDetermined 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

BURN 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

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)