Post-Mortem Changes

Time of Death

http://www.youtube.com/watch?v=GCyiczAcRBY

Time Since Death Interval

What Time Did the Person Die? Best estimate; offered with a reasonable

degree of medical and scientific certainty.

Impossible to be 100% accurate.

UNLESS a witness (who doesn’t lie) is present at the time of death, it generally is an estimate of time (2-4 hour window is the usual).

Indications of Death Indications of death:

Unconsciousness Loss of all reflexes No reaction to painful stimuli Muscular flaccidity Cessation of heart beat and respiratory movement Eye signs:

Loss of corneal and light reflexes Mid-dilated position of the pupils Irregular size and shape of the pupils Eyelids usually closed incompletely Tache noire: where the sclera remains exposed, two triangles

of

discoloration appear at each side of the cornea, either brown or

black.

Postmortem Ocular Changes

Immediate signs in eyes Dilated or fixed pupils

Absence of corneal and light reflex

Marked decrease in intra-ocular pressure

Late signs in eyes Cloudiness of cornea

Increase in potassium levels

Early Postmortem Ocular Changes

Eyes remain open Thin film observed over

cornea within minutes Taché noire

Eyes closed upon death Cloudiness within twenty-

four hours

Absence of intraocular fluid suggests more than 4 days.

Taché Noire

Terminology Following death many physiochemical

changes occur to the body Algor Mortis: Body temperature after Death

Livor Mortis: Discoloration after Death

Rigor Mortis: Stiffness after Death

Decomposition

Putrefaction and Autolysis

Time of Death To Evaluate Time Since Death:

Livor Mortis Rigor Mortis Body Temperature Stages of Decomposition Potassium Concentration in Vitreous Humor Stomach Contents Insect Activity Scene Markers Or a witness who can verify time of death

Algor Mortis Algor Mortis (Body Cooling)

Body cools from normal internal temperature to the temperature in the environment (ambient temperature). Liver or brain temperatures are taken for core

temperature

Body cooling is inaccurate in obtaining time of death.

Algor Mortis At 70°F – 75°F, the body cools 2.5°F to 2.0°F for

first hour, then 1.5°F to 2.0°F for next twelve hours, then 1.0°F for next 12 hours.

Time since death = 98.6°F – Rectal Temp (°F)/ 1.5 The rectum should be checked before insertion of the

thermometer (May have been a sexual assault)

Patient may not die immediately after assault. This may change time of death by several hours.

Measure inner core temperature Liver or brain

Factors affecting Rate of Cooling

Body weight: Larger bw: slower cooling Smaller bw: faster cooling

Edema: slower cooling rate.

Surface area of the body: Larger surface area speeds up cooling rate. Children have an increased surface area which

allows for rapid heat loss.

Factors affecting Rate of Cooling

Clothing and emaciation

Environmental Temperature: Higher humidity: rapid cooling rate Rapid air velocity: rapid cooling rate

Water: Rapid cooling rate: More rapid in flowing water than still water

If there is a fulminating infection, e.g. septicemia, the body temperature may continue to rise for some hours after death.

What is the Forensic Significance of Postmortem Lividity?

Helps in determining Time of death

Position of the body after death

Cause of death from color

Hypostasis is another term for Livor Mortis or Postmortem Lividity

Livor Mortis Purplish-blue discoloration due to the settling of

blood by gravitational forces within dilated, toneless capillaries of the skin

Livor is seen in the dependent areas On the back if the body was in a supine position or on

the face and front if the body remained prone The lividity doesn't show where the body is in contact

with something. Thus a body lying on its back will show lividity in the small of its back, its neck etc., but not parts of the body directly touching the ground.

This a very useful when determining if a body has been moved after death.

The areas where the blood has settled will turn pink to dark red to dark blue or purple.

Livor Mortis Starts happening immediately and is visible within

a couple of hours. At this point skin is pinkish/bluish and blotchy.

After five or six hours the blotches have joined up but the skin still goes white when pressed.

After ten to twelve hours the blue color remains even when pressed.

Within the areas of livor, pale areas where the skin was pressed against a hard surface or object will prevent postmortem sedimentation

Hypostasis/Livor Mortis

Blanching

Livor Mortis

Livor Mortis Postmortem Lividity

Early stages can “Blanch” the skin

Can shift position(s) from 1-8 hours

8-12 hours congeals in capillary beds

After 12 -24 hours the lividity is typically “fixed”

Can continue to move up to 3 days after death

Blanching

Thumb pressure indicates that the lividity is not fully fixed.

Blanching

Distribution of Hypostasis

If the body remains vertical after death as in hanging cases, hypostasis will be most marked

in the feet and to a lesser extent the hands.

Livor Mortis

Sites of Hypostasis Depends on the position of the body before death:

Supine: shoulders, buttocks heels pressing against surface gives white color (pale).

Vertical (hanging): distally in legs & feet.

Drowning: chest, upper chest, and upper limbs.

Face-down death: as in epilepsy, drunken victims whitening around nose & lips.

Hypostasis may also occur in viscera: Heart: mistaken for MI Lungs: mistaken for pneumonia Intestine: mistaken for hemorrhagic infarction

Lividity

Can you see hypostasis in the internal organs?

Yes

The lung is dark purple in the posterior dependent areas as a result of livor mortis. This may simulate congestion.

Lividity

Postmortem Changes Postmortem changes are affected by:

Victim’s Age

Victim’s Pre-morbid Health

Level of Activity at time of death

Type of drugs taken prior to death

Ingestion of drugs prior to death

Current Environmental conditions

Cause of Death Analyzed by Livor Mortis

Etiology Color of Liver Mechanism

Normal Red-Blue-Purple Venous Blood

Carbon Monoxide Pink, cherry-red Carboxyhemoglobin

Cyanide Pink, cherry-red Excessive oxygenated blood because of inhibition of cytochrome oxidase

Refrigeration/hypothermia

Pink, cherry-red Oxygen retention in cutaneous blood by cold air

Hydrogen sulfate Green Sulfhemoglobin

Sodium chlorate Brown Methemoglobin

Hypostasis vs. Bruises (Ecchymosis)

Hypostasis Bruises

Dependant areas Any where

Well defined edges Ill defined edges

Blood is retained in intact capillaries

Blood escapes through ruptured capillaries

Superficial Deep into skin

Same level on surface Raised

Pale over pressure areas

Red

Incision: blood flows from the cut vessel (washable)

Incision: blood coagulates in tissue

No swelling May be with swellingWith a bruise,

blood will not flow from the cut

Hypostasis In advanced stages, skin level capillaries

can hemorrhage This causes pinpoint breaks in the skin

called “Tardieu Spots” or petechiae.

Can see petechiae on internal organs.

These are minute hemorrhages in the soft tissue.

Scars show no lividity

Purpura = patches of purplish discoloration due to rupture of small vessels.

Tardieu Spots

Tardieu spots are petechiae and purpuric hemorrhages that develop in areas of dependency secondary to the rupture of degenerating vessels under the influence of increased pressure from gravity

Tardieu Spots

Tardieu Spots

Rigor Mortis = Stiffness After Death

After death muscles are initially flaccid and can be moved easily

The flaccidity is followed by increasing stiffness or rigidity of the muscles Joints are frozen

The rigidity will gradual subside and the body will be flaccid again

Postmortem Rigor Mortis

Rigor Mortis Chemical changes causes

muscle mass to become rigid; looks like body is frozen in place (fixed)

Small muscles go into rigor first

Rigor usually occurs from head to toe Rigor = Rigid Mortis = Death

Rigor Mortis Formation

Mechanisms Leading to Rigor: Metabolic activity after death continues for

short time and becomes anaerobic (lacking oxygen)

ATP hydrolyzes to ADP

Calcium ions diffuse from sarcoplasmic reticulum

Causes chemical lock between actin and myosin proteins, THEN

As body proteins decompose, chemical locks breakdown and muscles become flaccid again.

Time Table for Rigor Mortis

Rigor can be seen within 30 min. to 1 hour after death.

Covers the entire body after 8-12 hours. Complete Rigor will remain for about 8-12 hrs. Rigor begins to dissipate over the next 12 hrs.

This is dependent on environmental temperatures Fully flaccid body by 36 hours.

Cadaveric Spasm Drowning Great Excitement prior to death

Rigor Mortis Rigor is accelerated by

Prior exercise Convulsions Electrocution Hyperpyrexia Hot environmental temperatures Age (does not form well in children) Strychnine poisoning

Rigor is inhibited by Hypothermia Cold environment

Factors affecting timing of RM 

Environmental temperature: Cold and wet onset slow, duration longer

Hot and dry onset fast, duration shorter

Muscular activity before death: Muscles healthy and robust, at rest before death slow

onset, duration longer

Muscles exhausted/ fatigued onset rapid, esp in those limbs being used (eg in someone running at time of death, lower limbs develop RM faster than upper limbs)

Increase activity (convulsions, electrocution, lightning) rapid onset & short duration

 

Factors affecting timing of RM

Age: Extremes of age rapid onset

Health:

Cause of death: Asphyxia, pneumonia, nervous de’s with

muscle paralysis & dehydration slow onset

Septicemia & poisoning rapid onset, may even be absent, especially in limbs affected by septicemia

Emaciated or died of wasting disease rapid onset, short duration

RM: time estimation

Warm Flaccid Death < 3 hrs

Warm Stiff 3-8 hrs

Cold Stiff 8-36 hrs

Cold Flaccid Death > 36 hrs

What is the Forensic Significance of Rigor Mortis?

Can tell Time of Death

Can tell whether the body has been moved

May be able to tell cause of death

Cadaveric Spasm Known as instantaneous rigor, cataleptic

rigidity, or instantaneous rigidity

Rare form of muscular stiffening that occurs at the moment of death, persists into the period of rigor mortis and can be mistaken for rigor mortis

The cause is unknown, but usually associated with violent deaths happening with intense emotion

Occurs in deaths Of Drowning

That occur with great excitement of tension

Cadaveric Spasm

Rigor Mortis vs. Cadaveric Spasm

Rigor mortis Cadaveric spasm

Onset delayed after death (2-3 hrs)Duration approx 12-24 hrs

Onset is instantaneousDuration is a few hours, until it is

replaced by rigor mortis

Intensity comparatively moderate Intensity comparatively very strong

Mechanism of formation: breakdown of ATP below critical level

Mechanism of formation unknown, but predisposing factors: Excitement, fear, fatigue, exhaustion, nervous tension,

contraction of muscles at time of deathAll muscles of the body are affected

gradually.Selected muscles, which were in a state of contraction at the time of death, are

affected.

Cadaveric spasm in a drowning victim: had grass from the river bank firmly

clutched in the hand

What is the Forensic Significance of Cadaveric Spasm?

Diagnosis of suicide as in case of weapon found in hand

Drowning Diagnosis

ID of assailant as in case of evidence in hand

May allow one to know state of person prior to death Stress

Exercise

POST-MORTEM DECOMPOSITION

Postmortem Decomposition

The disintegration of body tissues after death

Tissue components leak and release hydrolytic enzymes

Bacteria and other microorganisms thrive on the organic material of the body

Two parallel process of decomposition occur: Autolysis: Self-dissolution by body enzymes

released from disintegrating cells

Putrefaction: Decomposition changes produced by the action of bacteria and microorganisms

Putrefaction The normal final sign of death.

Starts immediately after death at the cellular level

Becomes visible in 48-72 hrs.

Its onset may be sped up or delayed by several factors mainly: Temperature

The ambient temperature can speed up or slow down this process

A fever prior to death can speed up putrefaction Humidity

One week in air equals two weeks in water and eight weeks in soil

The 1st visible sign of putrefaction is green or greenish red discoloration of the skin of the anterior abdominal wall Normally starts in the right iliac fossa.

The Next phase: Gas formation Blisters containing red fluid appear on the skin,

mistaken as bleeding

Humidity, temperature, bacterial activity body proteins break into

polypeptides & amino acids

Brain & Epithelial tissues are the 1st to be affected by putrefaction

Heart, Uterus & Prostate may survive for longer periods.

Military Plaques: nodules in heart (epi/endocardial)

Marbling: bacteria colonize venous system hemolysis stain.

The decomposition of a body can be divided into several stages, even if the duration of each stage may vary a lot:

2 - 3 days: green staining begins on the right side of the abdomen. Body begins to swell.

3 - 4 days: staining spreads. Veins go "marbled" - a brownish black discoloration

5-6 days: abdomen swells with gas. Skin blisters

2 weeks: abdomen very tight and swollen.

3 weeks: tissue softens. Organs and cavities bursting. Nails fall off

4 weeks: soft tissues begin to liquefy. Face becoming unrecognizable

4 - 6 months: formation of adipocere, if in damp place. This is when the fat goes all hard and waxy.

A body without a coffin will be decayed within 12 years.

Marbling (Arborization)

Marbling

Marbling with Purging

PutrefactionThree Stages of Body Breakdown

Early Stage: 24-36 hours Green-like discoloration, usually in abdomen

(R-low) due to denaturation of bacteria in the colon

Early decompositional changes are manifested by green discoloration over

the abdomen.

Putrefaction Middle Stage: 36-48 hours

Gaseous bloating, green-purple color in face, neck and shoulders.

Putrefaction

Putrefaction

Putrefaction Late Stage: greater than 72

hoursBloatingPostmortem mucosal purge,

tongue swells and protrudes, venous marbling of subcutaneous vessels

Skin blebs or blisteringExplosion of this person can occur

Putrefaction

PutrefactionLate Stage (Cont.): greater than 72

hours

Skin and hair slippage skin of hands or feet can shed with nails

intact

Marked bloating (1-3X)

Skeletonization (from 4-5 days and up to 1.5 years depending on the climate).

Putrefaction

Putrefaction

Skin Slipage

Skin Slippage

Fingerprinting Using Finger From Deceased

Hair Slippage

Active Decay Greatest period of mass loss

Voracious feeding of maggots

Purging of decomposition fluids

Liquefaction of tissue and disintegration

This stage ends when maggots migrate from the body to pupate

Advanced Decay

Influences on Putrefaction A high environmental humidity will enhance putrefaction.

The rate of putrefaction is influenced by the bodily habits of the

decedent; obese individuals putrefy more rapidly than those who are

lean.

Putrefaction will be delayed in deaths from

exsanguination (bleeding to death) because blood provides a channel

for the spread of putrefactive organisms within the body. Conversely, putrefaction is more rapid in persons dying with widespread infection, congestive cardiac failure or retention of sodium and salts.

It tends to be more rapid in children than in adults, but the onset is

relatively slow in unfed new-born infants because of the lack of

commensal bacteria.

Influences on Putrefaction

Heavy clothing and other coverings, by retaining body heat, will speed up putrefaction.

Rapid putrefactive changes may be seen in corpses left in a room which is well heated, or in a bed with an electric blanket.

Injuries to the body surface promote putrefaction by providing portals of entry for bacteria and the associated blood provides an excellent medium for bacterial growth.

Timeline of Putrefaction

2–3 days: Discoloration appears on the skin of the abdomen. The abdomen begins to swell due to gas formation.

3–4 days: The discoloration spreads and discolored veins become visible.

5–6 days: The abdomen swells noticeably and the skin blisters.

2 weeks: The abdomen is bloated; internal gas pressure nears maximum capacity.

3 weeks: Tissues have softened. Organs and cavities are bursting. The nails fall off.

4 weeks: Soft tissues begin to liquefy and the face becomes unrecognizable.

The exact rate of putrefaction is dependent upon many factors such as weather, exposure and location

Case Study A 74-year old white male adult was found

dead in his one room apartment.

When police arrived they found him face down sprawled across his bed.

The room was approximately 75°F.

There were no apparent injuries to this individual.

Your Thoughts Police concluded the death was natural and

did not called the Coroner’s office.

Do you agree with their conclusion?

Why or why not?

Write down your answer and give a full explanation why you think the police were either correct or wrong. Make sure to use terminology presented in this

power point presentation.