1. Chapter 11 Death: Meaning, Manner, Mechanism, Cause, and Time By the end of this chapter you will be able to:
Discuss the definition of death
Distinguish between four manners of death: natural, accidental, suicidal, and homicidal
Distinguish between cause, manner, and mechanisms of death
Explain the development of rigor, algor, and livor mortis following death

2. Chapter 11 Death: Meaning, Manner, Mechanism, Cause, and Time By the end of this chapter you will be able to:
Estimate the time of death
Describe the stages of decomposition of a corpse
Use evidence on stomach contents to estimate time of death
Use insect evidence to estimate time of death
Explain how environmental factors can affect the estimated time of death

3. Video Real CSI: Crime Autopsy
Forensic Science: Fundamentals & Investigations, Chapter 11

4. Pig Decomposition

5. The Body Farm

6. Definition of Death
17th century, before the stethoscope, anyone in a coma or a slow heart rate was presumed dead and was buried
Cessation, or end, of life
1. Irreversible cessation of blood circulation
2. Cessation of all brain activity
3. Experts do not agree on a single definition

7. Introduction
Autolysis—cell breakdown

8. The Manner of Death The manner of death can be
Natural, the most common, caused by interruption and failure of body functions resulting from age or disease
Accidental
Suicidal
Homicidal
Undetermined
Sometimes the manner of death is difficult to determine

9. The Manner of Death What is the Manner of Death in these cases?
A man with a heart condition is attacked and dies from a heart attack during the assault.
An elderly woman dies after being kept from receiving proper health care by her son.

10. Cause and Mechanism of Death
Cause of the death is the reason for the death
Proximate cause of death – underlying cause of death
Mechanism of death is the specific change in the body that brought about the cessation of life
**usually only “Cause” and “Mechanism” are listed on the death certificate**

11. Time of Death—Livor Mortis
The Color of Death
Lividity—With decomposition, blood seeps down and settles in the lower parts of a body
Red blood cells turn bluish-purple

12. Time of Death—Livor Mortis
Lividity begins about two hours after death
Discoloration becomes permanent after eight hours
Ambient temperature affects the speed of decomposition
Lividity can determine the position of the body during the first eight hours
Dual lividity could occur if the body was kept in one position two hours after death and then moved to a second position before the lividity became permanent.

13. Time of Death—Rigor Mortis
The Rigidity of Death (Stiffness)
Without oxygen in the blood—
Calcium accumulates in the muscles
Muscles stiffen
Starts in the head and expands throughout
Begins after 2 hours
After about 15 hours—
Muscle fibers begin to dissolve
Softening begins
Ends after 48 hours

14. Time of Death—Rigor Mortis
Live muscle fibers slide back and forth
After death, muscle fibers become locked in a flexed position

15. Time of Death—Rigor Mortis
Observation
Approx. Time Scale
The body is at its most rigid state
12 hours
No visible signs of rigor
Less than 2 hours
or more than 48 hours ago
Stiffness generally disappears
After 36 hours

16. Time of Death—Rigor Mortis
Factors affecting rigor mortis:
Ambient temperature
Weight of the body
Type of clothing, or lack of it
General health of person at time of death
Level of physical activity at time of death
Sun exposure

17. Time of Death—Algor Mortis
Death heat (describes temperature loss)
Body heat falls after death
About 1.5 degrees per hour immediately after death
Slowing to less than 1.0 degree per hour after about 12 hours
Heat loss is affected by the ambient temperature
Corpse temperature is measured by a thermometer inserted into the liver
Time of death is expressed as a range of time

18. Time of Death —Stomach and Intestinal Contents
State of Contents
Timing of Death
Undigested food present in the stomach
Zero to two hours after the last meal
Stomach is empty, but food found in small intestine
Death occurred at least four to six hours after a meal
Small intestine is empty; waste found in large intestine
Death occurred 12 or more hours after a meal

19. Time of Death
—Stomach and Intestinal Contents

20. Time of Death —Stages of Decomposition
Choose: A. Within 2 days. B. After 4 days. C. Within 6-10 days.
Fluids begin to leak from body openings as cell membranes rupture
Discoloration of the face
The skin sloughs off
The skin blisters
Green and purplish staining from blood decomposition
The corpse bloats
Eyeballs and other tissues liquefy
The abdomen swells
Marbling appearance on the skin C A C B A C C B A
*The speed of decomposition depends on the person’s:
1) age 2) size of body 3) nature of death 4) health

21. Decomposition – Dirty Jobs

22. Decomposition – Dirty Jobs

23. Decomposition – Dirty Jobs

24. Time of Death—Insects Forensic entomologist
Collects insect evidence from on, above, and below the body
Records environmental conditions
Within minutes of a death, certain insects arrive to lay their eggs on the warm body—blowflies
As the corpse decomposes, other kinds of insects arrive

25. Time of Death —Blowfly Life Cycle
<8 hours after death—blowfly eggs can be found in the moist, warm areas of a corpse
Within 20 hours—1st of their 3 larva stages
4th or 5th day—3rd of their 3 larva stages
*The stages of larva can be determined by the number of spiracle slits at their posterior end
*An immature form of an animal that undergoes metamorphosis, for example a maggot, is a larva.

26. Time of Death —Blowfly Life Cycle
8 to 12 days—larvae migrates to a dry place
18 to 24 days— Early pupa; immobile; changes from light brown to dark brown
By the 21st-24th day the pupa cases will split open and adult blowflies will emerge.

28. Timeline 1.8 days First Stage (instar 1) V-shaped
2.5 days Second Stage (instar 2) two spiracles
4-5 days Third Stage (instar 3) three spiracles

29. Time of Death - Insects Accumulated Degree Hours (ADH)
Immediately preserve some insects from the crime scene.
At the crime lab, raise some of the insects from the crime scene in the same conditions as those found at the crime scene.
Record the length of time for development under the specific conditions found at the crime scene.
Compare the insects raised at the crime lab to those found at the crime scene.
A “maggot milkshake” is a blended group of maggots that have fed on
tissue and now are used to determine drug usage of the corpse.

30. Time of Death—Insects
The insect life cycle provides scientists with a benchmark to estimate a time of death
Insect evidence cannot provide:
*exact time of death
*fluctuating environmental conditions
Insect evidence provides a close estimate and may provide proof that the corpse has been moved.

31. . . . . . . . . . . . . . . . . . Summary Several definitions of death
A body decomposing through three stages— livor, rigor, and algor mortis—provides an estimated time of death
Stomach contents and insect evidence also aid in estimating the time of death
Environmental factors affect the estimated time of death