Forensics: Death Part 2 Decomposition

Death Part 2

Multiple Choice

True or False: The moment of death has a clear scientific definition.

• True

• False

Multiple Choice

An Autopsy is performed by which person?

• Detective

• Surgeon

• Pathologist

• Investigator

Multiple Choice

True or False: Trauma is an example of a mechanism of death

• True

• False

Multiple Choice

True or False: A cause of death and a mechanism of death are sometimes combined into one sentence

• True

• False

Livor Mortis

• Livor Mortis: The pooling of blood in tissues after death, coloring the skin

  • Translates as "Death Color"

• As a body decomposes, blood cells leak hemoglobin which collects on the bottom of the body and makes the skin look purple

  • Lividity: Pooling of blood in the body,

    • Occurs two hours after death

    • Becomes permanent eight hours after death

      • If the skin is pressed before the eight-hour mark, the color disappears

Factors that affect Livor Mortis

• Temperature

  • Reactions speed up in warm environments, so decomposition can occur faster in a warmer temperature and slower in a colder temperature

• Items on the body

  • Anything that can restrict blood flow can stop livor mortis from occurring in areas of the body like the limbs

    • Tight bands, ropes, etc.

What does Livor Mortis show?

• An Approximate time of death

  • Looking at how the coloring reacts when pressed can give an idea of how much time has passed

• The position of a body during the first eight hours after death

  • Can help indicate if a body has been moved based on how many places lividity occurs

• Details about a crime

  • If livor mortis is not seen is areas you would expect it, it could indicate that something was restricting blood flow and the scene was tampered with

Drag and Drop

Livor Mortis results in the body changing to a purple color due to ​

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leaking from ​

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and being pulled downwards.

Drag these tiles and drop them in the correct blank above

hemoglobin

blood cells

blood

liver

stomach contents

stomach

heart

Multiple Choice

What term describes the pooling of blood inside the body?

• Hemopuddling

• Lividity

• Autolysis

• Leukidity

Rigor Mortis

• Rigor Mortis: The Stiffening of the skeletal muscles after death

  • Is temporary and generally disappears after 36 hours

• Starts within two hours after death

  • Works its way down the body starting at the head

• The Body is the most rigid after 12 hours

Why does Rigor Mortis Occur?

• When a person is living, their body uses ATP to move their muscles

  • ATP is formed in the body and recycled to keep functions working

  • Removes Calcium from the muscle

• After death, the reactions that make ATP cease, so the muscle start to collect calcium which causes them to stay stiff

• Over time, the muscles begin to decompose and relax

Factors that affect Rigor Mortis

• Environmental Temperature

  • Cold=Slow, Warm= Fast

  • Extra Sunlight can make a body warmer and speed up Rigor

• Body Weight

  • Fat stores Oxygen which is needed to make ATP. The more Oxygen in the body, the longer the ATP reaction can take place after death

• Clothing

  • Clothes add warmth to a body, which can speed up rigor mortis

Factors that affect Rigor Mortis

• Illness

  • A fever is an elevated temperature, which can speed up Rigor

  • Hypothermia can slow it down

• Physical activity before death

  • If someone was active before death, they will have used more oxygen and have a higher temperature

What does Rigor Mortis Show

• On its own, Rigor mortis is not very helpful in establishing the time of death

  • Too many factors can influence the process

• It can be used as supporting evidence when combined with other factors

Multiple Choice

True or false: rigor mortis is a permanent change in the body

• True

• False

Multiple Choice

Which compound can be stored in body fat that slows down the process of rigor mortis?

• Calcium

• Water

• Hemoglobin

• Oxygen

Algor Mortis

• Algor Mortis: The cooling of the body after death

  • When the body is alive, it needs to maintain a constant temperature of ~37°C to function

  • After death, the body begins to cool down

• The temperature of a body is taken by inserting a thermometer into the liver

  • Using the Liver gives all investigators a standard for comparison

• In "normal" conditions body temperature decreases by 0.39°C per hour until the body is at the same temperature as the surroundings

  • Temperature is rarely "normal", so the time of death is given as a range of time instead of a specific time

Factors that affect Algor Mortis

• Surrounding Environment

  • Extreme temperatures and humidity can change the rate of heat change

• Excess body fat and clothing can insulate the body and slow the temperature change

• Illness that can raise the body's initial temperature can skew the rate of change

Multiple Select

Temperature affects which of the following events after death?

• Livor Mortis

• Rigor Mortis

• Algor Mortis

• Temperature has no effect on a body post deat

Stomach and Intestinal Contents

• When performing an autopsy, stomach and intestinal contents are often observed to help place a time of death

  • Normally, it takes between 4-6 hours for food to move from the stomach to the small intestine

  • It takes food 12 hours for food to go through the small intestine, and another 12 hours to leave the large intestine

Stomach and Intestinal Contents

• If there is stomach content, you can conclude that death occurred zero to four hours after the last meal

  • If the food is undigested, the time frame is shortened to two hours

• If the stomach is empty and food is found in the small intestine, death occureed at least 4-6 hours after a meal

• If both the stomach and small intestine are empty and food is found in the large intestine, death occured around 12 or more hours after a meal

Hotspot

If a person ate their last meal 3 hours before death, where is the most likely place you would find digestive contents

Multiple Select

If a person had been fasting all day before their death, Where could you expect to find contents in their digestive system,

• Stomach

• Small Intestine

• Large Intestine

• They should have nothing in their digestive system

Decomposition

• Decomposition: The rotting of all tissue and organs after death

  • Caused by microorganisms digesting tissues

• Speed can depend on different factors

  • Age

    • Young decompose faster than old

  • Size

    • More fat breaks down quicker than less fat

  • Nature of death

    • sick people decompose more quickly than healthy people

  • Coverings on the body slow down decompostion

Decomposition

• Speed can depend on different factors

  • Moisture

    • water contains oxygen that can speed up decomposition

  • Temperature

    • Ideal range: 21-37° C

    • Too hot a temperature can dry a body out and prevents decomposition

    • Too cold prevents bacteria growth and prevents decomposition

Stages of Decomposition

• Stage 1: Starts Within two days after death

  • Cell autolysis begins

  • Skin begins to show green/purplish staining and looks marbled

• Stage 2: Starts after four days

  • Skin forms blisters

  • The abdomen swells from Carbon Dioxide Gas released by intestinal bacteria

Stages of Decomposition

• Stage 3: Occurs within 6-10 days

  • Carbon Dioxide continues to build up until the chest and abdomine bursts/collapses

  • Fluids leak from the body as cell membranes rupture and tissues liquefy

  • the skin sloughs off

Multiple Choice

True or False: Raising the temperature speeds up decomposition of a body.

• True

• False