Unit 2 forensics science- death and the body

manner of death

The official classification of the circumstances surrounding how a persons death occured.

example of Manner of Death

• Suicide

• natural: caused by natural death; age, illness, etc

what are the 5 manners of death

1. Natural

2. Accidental

3. suicidal

4. homicidal

5. undetermined

Mechanism of death

The specific physiological or biochemical disturbance that results in a person dying

example of mechanism of death

sepsis: widespread infection, inflammation

cause of death

medical condition, disease, injury, or trauma that starts the chain of events leading directly to a persons death.

cause of death example:

heart disease

time of death

the exact or estimated time when a person’s vital life functions permanently cease.

example of time of death

The victim died at 3:30pm

decomposition

the process of breaking down complex substance problems, or organisms into similar parts

stages of decomposition

1. Fresh- body just died

2. Bloat- gases build up in body

3. Active decay- body breaks down further

4. Advanced decay- most soft tissue is gone

5. Dry remains- Bones, skin, and tissue remain

Autopsy

An examination of a body after death to find out how they died

who performs an autopsy?

forensic pathologist or medical examiner

whats the importance of an autopsy?

helps find cause of death and help provide evidence for investigators

the body farm

It is a research facility where donated human bodies are studied while they decompose

who founded it

Dr. William Bass, in Knoxville Tennessee at UT

Purpose of the Body Farm

To study how human bodies decompose and help solve crimes

what is post mortem

after death

death

• cessation, or end of life

• irreversible cessation of blood circulation

• cessation of all brain activity

• experts do not agree on a single definition

time since death

• the time frame between death and discovery of an organism.

• Often times in a forensic investigation, the time of death is important in providing insight to the crime being investigated.

• Post mortem (after death) - is when the body changes in a fairly predictable manner.

• Forensic investigators study the decomposition stages of a body as it decays and other post mortem changes that occur

What are the factors scientists use to determine Time of Death

• Livor Mortis

• Rigor Mortis

• Algor Mortis

• Stomach/Intestinal contents

• Stages of decomposition

• Insects (entomology)

Livor Mortis

• Meaning: Death Color

• As the body begins to decompose, blood seeps down through the tissues and settles into the lower parts of the body.

• A purplish color is visible on the parts of the skin where the blood settles

• Lividity: known as the pooling of blood in the body

• lividity begins 2 hours after death

• Lividity is permanent after 8 hours

• Lividity can also tell the position of the body within the first 8 hours of death

• Ambient temperature is the temperature of the crime scene and it’s surrounding areas

• Hot temperatures: Livor mortis occurs quicker

• Cooler temperatures: livor mortis occurs more slowly

Rigor Mortis

• meaning: Death stiffness

• Rigor is temporary and can be useful in determining TOD

• Rigor mortis starts within 2 hours after death

• It starts in the head, and works it way down to it’s legs

• After 12 hours, the body is at it’s most rigid state.

how long does the stiffness start to disappear?

after 24 hours

A body that shows no rigor, has most likely been dead less than

2 hours or more than 36

what is rigor dependent on?

• Ambient temperature: cold temperatures slow rigor, heat speeds it up

• Weight: the more a person weighs, the faster rigor will occur.

• clothing can act as insulation (Naked bodies = cooler temp = slower rigor)

• illness: fever = higher temperature = faster rigor

• Sun expose: faster rigor

Algor mortis

Meaning: temperature loss after death

when someone is alive, do they maintain constant temperature?

yes

When someone dies, the body no longer generates____ and begins to lose heat

heat

temperature of a corpse is taken ______ or via the ____

rectally, liver

normal body temp:

98.6 degrees F

Is algor mortis the most accurate method of estimating time since death?

yes

Rules of Algor Mortis:

1. In warmer environments, heat is lost more slowly

2. In cooler environments, heat is lost more rapidly

3. In ambient temperatures that are higher than the body’s temperature, heat will actually be gained by the body

4. After 1 hour of death, the body cools at a rate of 1.4 ° per hour.

5. After the first 12 hours, the body loses 0.7° F per hour until the body reaches the same temperature as its surroundings