1. Essential Question(s) Enduring Understanding(s)
Unit 5 Chapter 11 Death: Manner, Mechanism, Cause, and Time By the end of this chapter you will be able to:
Essential Question(s)
Enduring Understanding(s)
Discuss the ways in which a person can die.
Explain how time of death can be determined.
Describe the roles of a forensic pathologist, forensic entomologist and forensic anthropologist in a crime scene investigation.
Describe how bones can provide insight into the life and death of a person.
Forensic investigators must determine the time and cause of death and understand that death can occur in many different ways.
Insect evidence and environmental factors must be considered when approximating the time of death.
There are visible differences between the male and female skeleton, especially the skull, jaw, brow ridge, pelvis and femur.

2. Death The Manner of Death
Farm clip
The Manner of Death
The manner of death can be natural, accidental, suicidal, homicidal, or undetermined.
Sometimes it is difficult to determine the manner of death.
The most common manner of death is natural.
Forensic Science: Fundamentals & Investigations, Chapter 11

3. Cause and Mechanism of Death
The reason for the death is the cause of the death. (ex: shooting)
The specific change in the body that brought about the cessation of life is the mechanism of death. (ex: loss of blood)
Forensic Science: Fundamentals & Investigations, Chapter 11

4. Time of Death—Livor Mortis
The Leaden-Color of Death
When red blood cells break down, they turn a bluish-purple.
With decomposition, blood seeps down and settles in the lower parts of a body.
The discoloration that accompanies this becomes permanent after 8 hours.
Warmth accelerates the process.
Forensic Science: Fundamentals & Investigations, Chapter 11

5. Time of Death—Rigor Mortis
The Rigidity of Death
At death, skeletal muscles cannot relax.
Without oxygen, calcium accumulates in these muscles.
The muscles become stiff.
This starts in the head and works its way down to the legs.
After about 15 hours, the muscle fibers begin to dissolve, and softening begins.
Forensic Science: Fundamentals & Investigations, Chapter 11

6. Time of Death—Rigor Mortis
At 12 hours after death, the body is at its most rigid state.
If a body has no visible signs of rigor, it probably has been dead less than 2 hours or more than 48.
If the body exhibits rigor only in the head and neck, the time of death is just over 2 hours.
This stiffness will have disappeared for the most part after 36 hours.
Forensic Science: Fundamentals & Investigations, Chapter 11

7. Time of Death—Rigor Mortis
Many factors affect when rigor mortis sets in and how long it lasts:
Ambient temperature
The weight of the body
The body’s clothing or lack of it
Any illness the person had at the time of death
The level of physical activity at the time of death
Sun exposure
Cold: slows
Warmth: accelerates
Obese: slows
Thin: accelerates
Aerobic activity: accelerates
Sleep: slows
Forensic Science: Fundamentals & Investigations, Chapter 11

8. Body becomes stiff and stiffness moves down body
Time after death
Event
Appearance
Circumstances
2- 6 hours
Rigor begins
Body becomes stiff and stiffness moves down body
Stiffness begins with the eyelids and jaw muscles after about three hours, then center of body stiffens, then arms and legs
12 hours
Rigor complete
Peak rigor is exhibited
Entire body is rigid
15-36 hours
Slow loss of rigor
Loss of rigor in small muscle first followed by larger muscles.
Rigor lost first in head and neck and lastly in bigger leg muscles
36-48 hours
Rigor totally disappears
Muscle become flaccid
Many variables may extend some extend of rigor beyond the normal 36 hours
Factors Affecting Rigor
Effect
Temp
Cold
Inhibits rigor
Slower onset and slower progression
Warm
Accelerates rigor
Faster onset and faster progression
Activity before death
Aerobic exercise
Lack of oxygen to muscle accelerates
Sleep
Slows rigor
Muscles fully oxygenated will exhibit rigor more slowly
Body weight
Obesity
Fat stores oxygen
Thin
Body loses oxygen quickly
Forensic Science: Fundamentals & Investigations, Chapter 11

9. Time of Death—Algor Mortis
The Chill of Death
In death a body no longer generates warmth and begins to cool down.
To find the standard temperature of a corpse, a thermometer is inserted into the liver.
Body heat is lost at about 1 to 1.5 degrees an hour.
Time of death determined by temperature calculations is expressed as a range of time.
Forensic Science: Fundamentals & Investigations, Chapter 11

10. How long does it take for a body to cool?
1st 12 hrs the body loses 1.4°F per hour
Next 12 hrs the body loses 0.7°F per hour
Cools faster in colder temps
How much heat is lost during 1st 12 hrs?
1.4°F x 12 =
If body temp is less than 81.8°F the person died 12 hrs ago (or more)
16.8°F

11. Calculate TOD, body temp is 90°F?
98.6°F - 90°F =
# of hrs = 8.6°F/1.4°F
# of hrs =
The person died 6 hrs and 6 minutes prior to finding body
8.6°F
6.1

12. Calculate TOD, body temp is 72°F?
During 1st 12 hrs the body temp drops to 81.8 oF
81.8°F - 72°F = lost after 12 hrs
# of hrs = 9.8°F / 0.7°F
# of hrs =
= 26 hrs since death
9.8°F 14

13. Body Temp greater than 81.8oF
98.6oF – body temp = a /1.4 = # hrs since death
Body Temp less than 81.8oF
81.8oF – body temp = a / 0.7 = b = # hrs since death
Complete Activity 11-2 part A and B on pgs

14. Time of Death—Stomach and Intestinal Contents
Based on these specifics, give an estimate for each of these on how much time has passed since the meal was eaten:
Food is still present in the stomach.
The stomach is empty but food is found in the small intestine.
The small intestine is empty but waste is present in the large intestine.
0-2 hrs
4-6 hrs
12 hrs or more
Forensic Science: Fundamentals & Investigations, Chapter 11

15. Time of Death—Stages of Decomposition
Lapse Video of Pig Decmop....
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
Forensic Science: Fundamentals & Investigations, Chapter 11

16. Fresh Bloat Active decay Advanced Decay Dry Remains
Purification
Marbling
Fresh Bloat Active decay Advanced Decay Dry Remains
Forensic Science: Fundamentals & Investigations, Chapter 11

17. http://entomology clip
Time of Death—Insects
Besides recording data about the environment at a crime scene, a forensic entomologist collects insect evidence.
Within minutes of a death, certain insects arrive to lay their eggs on the warm body. Blowflies are a common example.
As a corpse progresses through the stages of decomposition, other kinds of insects arrive.
Forensic Science: Fundamentals & Investigations, Chapter 11

18. Time of Death—Insects
Blowfly eggs can be found in the moist, warm areas of a corpse within 8 hours after death.
They will have progressed to the 1st of their 3 larva stages within 20 hours.
By the 4th or 5th day they will have progressed to the 3rd of their 3 larva stages.
Forensic Science: Fundamentals & Investigations, Chapter 11

19. Time of Death—Insects
By the 8th or 12th day the larvae will migrate away from the corpse to a dry place.
Becoming pupa and immobile within days, they will change from white to dark brown.
By the 21st-24th day the pupa cases will split open and adult blowflies (illustration of one shown above) will emerge.
Forensic Science: Fundamentals & Investigations, Chapter 11

21. Examples of Diptera (Flies)
Early Stage Decomposition
Blow & Greenbottle Flies
(Calliphoridae)
Metallic thorax and abdomen
Flesh Fly
(Sarcophagidae) Striped thorax
Life Cycle of a Calliphoridae Fly
Late Stage Decomposition
House Fly
(Muscidae)
Cheese Skipper
(Piophilidae)
Informational Source: Images: Top Left - Middle-Left: Top Right - Bottom -

22. Examples of Coleoptera (Beetles)
Early Stage Decomposition
Early to Late Stage Decomposition
Rove Beetles
(Staphylinidae)
Predator of fly eggs
Clown Beetles
(Histeridae)
Predator of fly eggs
Carrion Beetles (Silphidae) Adults & larvae feed on fly larvae
Late Stage Decomposition
Ham & Checkered Beetles (Cleridae) Predator of flies & beetles;
also feed on dead tissue
Hide Beetles (Scarabidae) Usually the last to arrive
Skin Beetles (Dermestidae) Feed on dried skin & tissues
Informational Source:
Images: &

23.
Time of Death—Insects
Because scientists know how long it takes for the various stages of development at given temperatures, forensics entomologists can determine when the insects arrived.
Because life cycles are affected by fluctuations in the daily environmental conditions, insect evidence cannot provide an exact time of death.
Insect evidence, nonetheless, can yield a close estimate.
Forensic Science: Fundamentals & Investigations, Chapter 11

24. Summary
A body decomposes through the 3 changes of livor, rigor, and algor mortis.
Forensic scientists use evidence from these to estimate the time of death.
They also use stomach contents and insect evidence to estimate the time of death.
It is also important to remember how environmental factors can affect the estimated time of death.
Forensic Science: Fundamentals & Investigations, Chapter 11