Death and Decomposition

What is Death in Biology and who clarifies death?

a process in which the cells and tissues of an organism cease to function

When a qualified individual pronounces that a life is now extinct; recorded on a death certificate

What are the Mortems

Ante- mortem

peri-mortem

Post-mortem

Agonal period

Post-mortem interval

Before death (What mortem)

Ante-mortem

At around time of death (What mortem)

Peri-mortem

After death (What mortem)

Post-mortem

The moment of death (What mortem)

Agonal Period

Post-Mortem Interval

Time Since Death

What is Death in Forensic Science? What is the terminology for humans 

Differentiate between normal and abnormal processes

• Estimate cause and manner of death

• Estimate PMI

• Establishing if a crime did or did not occur

(Usually by the medical examiner, Coroner, foresnic pathologist, forensic anthropolgist)

Term: Corpse, cadaver, body, individual, remains, skeleton

What is Decomposition?

Act or process of the reduction of matter into simple forms

Process involves physical changes, intracellular and chemical changes

What are the stages of Decomposition?

• complex, chaotic, non-linear, systematic continuum

-Fresh, bloat, putrefaction, putrid dry remains

What factors impact decomposition?

• Intrinsic versus extrinsic • Biotic versus abiotic

• Microbes, insects, scavengers

• Individual, environment, behavior

What are the immediate first changes?- Somatic/somatic death 

• Somatic: relating to the body

• Somatic death: cessation of at least one of the main bodily systems • Respiratory, circulatory, nervous

• Somatic death initates celluar death

What are the fresh changes: Early? and the different rates cells die

Cellular death: death of cells due to lack of oxygen and other nutrients

Brain cells: 3-7 minutes

Skin cells: up to 24 hours

What are the different mortis

• Pallor = pale/ Paleness of death

• Livor = bluish color, bruise/Blueness of death

• Algor = cold /Coldness of death

• Rigor = stiff • Stiffness of death

What happens in Pallor Mortis 

• Somatic death = cessation of bodily systems

Without blood pressure, gravity causes blood to settle

-Creates Pallor Mortis 

-Begins 20 minutes after death 

Opposite of where the blood settles is pale, from lack of blood in capillaries under the skin the 

What is Livor Mortis

Somatic death = cessation of body systems → gravity pools blood

• Blood pooling is livor mortis, or hypostasis

• Skin where blood pooled underneath appears red to blue/purple/green

• Begin with patches or blotches

• Move to full development, confluence

• Maximum intensity

• Become fixed

What are the color changes in Livor Mortis?

• Red → Blue/purple → Green tint

Red color comes from oxygenated blood • Oxygenated blood = oxyhemoglobin → bright red in color

Blue/purple color comes from deoxygenated blood • Deoxygenated blood = deoxyhemoglobin → blue/purple in color

Over time, cells will lyse (breakdown) • Revert oxyhemoglobin to deoxyhemoglobin

Green color comes from sulfhemoglobin

• Cell lysis causes oxygen to separate from hemoglobin

• Cell lysis also releases cytoplasm into the surrounding tissue

• Released oxygen reacts with hydrogen sulfide

Creates sulfhemoglobin → greenish color

What is Livor Mortis timing?

• Blood pulled by gravity immediately after loss of blood pressure

• Moves slowly

• Visible patches: 30min to 2hr

• Complete confluence: 4hr to 6hr

• Maximum intensity: 6hr to 10hr

• Fixed: 12hr to 24hr

What is Algor Mortis and the influential factors

Thermoregulation stops— moves to ambient temperature

Normal body temperature (98.6 F). Ambient temperature is below this (cooling)

• Body weight

• Body position

• Body mass index in relation to surface area

• Sex of deceased

• Environmental conditions

• Surface insulations

What is Rigor Mortis and the steps?

First: total relaxation of all muscles immediately after death

• Then: Rigor  Stiffening and shortening of muscles

• Rigor develops across all muscles at roughly same time and speed

• Stiffening begins in eyelids and jaw

Fully developed 6 to 18 hours after death

What is loosening rigor?

Fully developed rigor can be called the rigid stage

After the rigid stage, the process will reverse

• Muscles will lose rigidity in the order it appeared

• Small to large • After another ~12 hours, the body will lose all rigor

Process can begin 24 to 36 hours after death/ • After this, rigor cannot be assessed to estimate PMI

What is Rigor Mortis Influential Factors

• Rigor impacted by extrinsic and intrinsic factors

• Environment

• Higher temperature = earlier/faster development

• Lower temperature = later/slower development

• Individual •

Body mass, muscle mass • Activity prior to death

What is Cadaveric Spasm?

Complete and instantaneous rigor

Cadaveric rigidity or Instantaneous rigor

Occur in deaths with extreme physical/ emotional stress (rare)

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