1. Time of Death

2. Death usually occurs after the breathing stops and the heart stops pumping blood through the body.
Death is a process, not an event. The decomposition process after death has 5 stages.
Initial decay
Putrefaction
Black putrefaction
Butyric fermentation
Dry Decay

3. Initial Decay 0-3 days after death
The outside of the body appears fresh.
Bacteria in the intestines start to feed on the intestines themselves
The bodies own digestive enzymes start to break down the organs
Insects arrive

4. Initial Decay
Insect Eggs

5. Initial Decay

6. Putrefaction 4-10 days after death
Bacteria breaks down tissues and cells, releasing body fluid into cavities.
Bacteria also produce gases as waste products.
People find these gases to be foul smelling but insects are attracted to them.

7. Pig bloated due to bacteria producing gas.
Putrefaction
Pig bloated due to bacteria producing gas.

8. Putrefaction
Insects attracted to the smell of gases

9. Putrefaction
Maggots feeding under the skin

10. Black Putrefaction 10-20 days after death
The bloated body collapses and large volumes of fluid drain from the body attracting more insects.
Flesh takes on a creamy consistency and exposed skin turns black.
Insects and bacteria continue to eat flesh

11. Body has collapsed with black exposed flesh
Black Putrefaction
Body has collapsed with black exposed flesh

12. This stage attracts a wide variety of insects
Black Putrefaction
This stage attracts a wide variety of insects

13. Black Putrefaction
The body has collapsed

14. Butyric Fermentation 20-50 days after death
The remaining flesh is removed and dries out, the body produces butyric acid.
The part of the body in contact with the ground gets moldy as the body ferments.
The cheese fly consumes any moist flesh left as beetles feed on skin and ligaments.

15. The body is now flat and dried out
Butyric Fermentation
The body is now flat and dried out

16. Butyric Fermentation

17. Dry Decay 50-365 days after death
The body is now dry and decays very slowly
Eventually the hair disappears and leaves only the bone.

18. Time of Death
If an investigator can determine the time of death, they may be able to place a suspect at a particular crime scene during a particular time slot.
There are several ways investigators can establish time of death.

19. Time of Death
Algor Mortis- After death the body cools from it’s normal internal temperature of 98.6 degrees to the surrounding environmental temperature.
Average cooling rate of a dead body is 1.5 degrees/hour.
Variables that effect algor mortis
Body Fat
Clothing
Air Temperature

20. Time of Death
Rigor Mortis- the muscles of the corpse become stiff and the body is frozen in position.
*Initial onset- 3-4 hours after death
*Starts in the jaw, neck and spreads down the body
*Complete rigor hours after death
*Rigor ends hours after death
Variables that effect Rigor mortis:
Heat Changes Rate
Individual Muscular development

21. Rigor mortis has left this mans arms stiff

22. Time of Death
Livor Mortis – After the heart stops the blood, pulled by gravity, sinks to the lowest part of the body. This causes purplish discoloration.
Starts 2 hours after death - remains for 12 hours
Clothing can restrict movement of blood
Can be used to determine what position the body was in upon death and if it was moved.

23. Time of Death
Stomach Contents - The stomach empties at regular intervals. Analysis is preformed at autopsy.
Light Meal - 2 hours
Medium Meal hours
Heavy Meal - 6 or more hours
Small Intestines empty every 12 hours or more

24. Time of Death
Ocular Changes - Cells in the eyes release potassium after death. Causes eyes to cloud over.
Release of potassium occurs at a constant rate
Measuring potassium in ocular fluid can determine when death occurred
Preformed at the time of the autopsy

25. Variables that effect Insects:
*Weather - Cold can slow or stop life cycle
*Location - Different areas might have
different insects
Time of Death
Forensic Entomology- use of insects to aide in legal investigations. Forensic entomology can help to determine time of death.

26. Forensic Entomology
Upon death the first insects to arrive are Calliphorids or blow flies.
Blow flies lay eggs on corpse as soon as minutes after death. They lay their eggs in natural (mouth, nose, eyes) and mechanical (gunshot, knife wound) orifices. These flies are only active in the day.

27. After about 24 hours the Calliphora eggs hatch into larvae (maggots)
After about 24 hours the Calliphora eggs hatch into larvae (maggots). They go through several stages then turn into a pupa (7-11 days).
About 12 days after the pupa stage the adult fly emerges and flies away.

28. American Carrion Beetle
Once putrefaction starts other insects such as flesh flies appear.
Flesh-fly
Sexton Beetle
American Carrion Beetle
Beetles now arrive. The flesh-fly larvae and beetles are predacious, meaning they feed on eggs and larvae of other insects.

29. During Black putrefaction is when the majority of necrophagous insects arrive. These include Phoridae (coffin fly), Muscidae (house fly), Sepsidae (black scavenger fly), and Histeridae (Hister beetle).
Coffin Fly
House Fly
Hister Beetle

30. During Butyric Fermentation the body becomes drier making conditions less conductive to rearing young insects. Insect activity and presence decline.
Hide Beetle
Clothes Moth
Mites
Dry decay leaves mostly hair and bone. This attracts insects such as Dermistidae (Hide beetle), Acari (mites), Tineidae (clothes moths), and roaches.

31. Knowing insect life cycles and growth rates can help to determine Time of Death.
18-24 Days
Eggs
Adult fly
For example if you find Blow-fly pupa on the corpse and you know it takes about 12 days for the eggs to mature to that stage, you can estimate the time of death to be days. This includes a two day error factor.

32. Review Define the following terms:
Algor Mortis-
Rigor Mortis-
Livor Mortis-
Cooling of the body after death
Stiffening of the muscles after death
Settling of the blood after death
What factors can affect the rate of algor mortis and rigor mortis?
Environmental temperature
Clothing worn
Individual muscle development

33. Review
Name two ways to determine Time of Death that need to be done at an autopsy
Stomach Contents
Ocular Changes
Define Forensic Entomology-
The use of insects to aide in an investigation.

34. Colliphorids or blow-flies
Review
Which insects are the first to arrive on a dead body?
Colliphorids or blow-flies
How can insects aide in determining Time of Death?
You can use decomposition or succession of insects to determine a rough estimate. A more accurate estimate can be determined through knowledge of larvae development and growth rates.

35. Why do some insects show up in later stages?
Review
Why do some insects show up in later stages?
Some insects are predacious and feed on the larvae of others, therefore they have to wait until insects such as blowflies lay their eggs.
Name some examples of predacious insects.
Sarcophagidae- Flesh flies
Silphidae- American carrion beetle, Sexton beetle
Which insects are last to arrive?
Dermistidae-Hide beetle, Tineidae- Clothes moth,
Acari- Mite. They show up to finish off bones and hair.