1. Method for determining
Time of Death
Method for determining

2. Rigor Mortis “death stiffness”
results in the shortening of muscle tissue and the stiffening of body parts in the position at death (occurs within the first 24 hrs. and disappears within 36 hrs.).
Starts in the head and works its way down to the legs.
At 12 hours the body is most rigid.
Skeletal muscles cannot relax.
When you are alive, muscles release Calcium to contract. This Calcium is removed from the cells, which requires energy. In death, there is no energy, thus Calcium is not removed and the muscles remain contracted.
After 12 hours, the muscle cells begin to dissolve by autolysis

3. Factors that affect rate of rigor mortis
Environmental temperature – cooler, slower
A person’s weight – Body fat stores extra oxygen (therefore more energy is available after death)
Type of clothing – Clothing keeps the body warm
Illness – fever vs. hypothermia
Level of activity before death – high activity, faster
Sun exposure – Direct sunlight, warmer, faster

4. Livor Mortis “Death Color”
results in the settling of blood in areas of the body closest to the ground (begins immediately on death and continues up to 12 hrs.).
Red Blood cells break down, spilling out hemoglobin. This turns purple, outside of the cell. This is visible where the blood pools.
“Lividity” – pooling of the blood. Discoloration is permanent after 8 hours.
Environmental factors affect the rate

5. Lividity Pooling of blood Can provide time of death
Can reveal the position of a corpse during the first 8 hours
Face down?
On back?
Standing?
Reveal if the body has been moved

6. Algor Mortis “Death Heat”
results in the loss of heat by a body (a general rule, beginning about an hour after death, the body loses heat by 1 to 1 1/2 degrees Fahrenheit per hour until the body reaches the environmental temperature).

7. Predictable Pattern of Decay
Fresh
Body is intact, decay inside body
Lasts until body becomes bloated
Blow flies (Calliphoridae) and Fresh flies (Sarcophagidae are among first to arrive
Bloated
Body becomes visibly inflated due to the production of gases from bacteria that begin to putrefy the body
House flies (Muscidae) now join other flies
Decay
Skin breaks and body deflates
Smells BAD
Most maggots have finished development

8. Pictures of Process Fresh Bloat Decay
Pigs used because have similar fat content to human
Decay

9. Butyric Fermentation
All the remaining flesh is removed over this period and the body dries out.
It has a cheesy smell, caused by butyric acid, and this smell attracts a new suite of corpse organisms. .
Insect activity
The reduction in soft food makes the body less palatable to the mouth-hooks of maggots, and more suitable for the chewing mouthparts of beetles.
All the remaining flesh is removed over this period and the body dries out. It has a cheesy smell, caused by butyric acid, and this smell attracts a new suite of corpse organisms.
The surface of the body that is in contact with the ground becomes covered with mould as the body ferments.
Insect activity
The reduction in soft food makes the body less palatable to the mouth-hooks of maggots, and more suitable for the chewing mouthparts of beetles. Beetles feed on the skin and ligaments. Many of these beetles are larvae. They hatch from eggs, laid by adults, which fed on the body in earlier stages of decay.

10. Newton’s Law of Cooling
Newton’s Law of Cooling describes the cooling of a warmer object to the cooler temperature of the Environment
T(t)=Te+(To-Te)e-kt
To is initial temperature of object (98.6 degrees F)
Te is constant temperature of environment
T(t) is the temperature of the object at any time t (from graph)
k is a constant

11. Graph of Newton’s Law of Cooling

12. Anthropology
Forensic Anthropology is concerned primarily with the identification and examination of human skeletal remains.
Radiologic dating uses carbon dating techniques to determine approximate age of bones

13. Carbon Dating Carbon-14 is an isotope of carbon
Isotopes have the same number of protons, different numbers of neutrons
Carbon-14 dating can be used to find the ages of once-living things because all organism absorb Carbon-14 when they are alive
Once an organism dies, its body begins to lose Carbon-14 at a fixed rate.
Scientists can measure the amount of Carbon 14 remaining in a skeleton to determine the date the person died.
Isotope -- same number of protons different number of neutrons

14. Half -life -- the amount of time for 1/2 of the sample to decay

15. Entomology
Forensic Entomology is the study of insects and their relation to a criminal investigation, commonly used to estimate the time of death.

16. Of Maggots and Murder Flies are among first to colonize carcass
Usually arrive within 10 minutes
As carcass decays, conditions change
Drier
Temperature drops
Tissues break down

17. Order of Insect Appearance
Blowflies
Other flies
Tiny Wasps (lay eggs on maggots)…live as parasites in maggots
Beetles and Mites (when body is drier)

18. Blowfly Development Egg (8 hours) Larva 1 (aka “instar 1”)
Pre-pupa
Early and late pupa
Adult
Changes in size, color, mobility and external physical changes enable a scientist to determine when the blowflies arrived at the body.

19. Orifices and Openings
When flies arrive, search out natural orifices (mouth, ears, nose)
If larvae are found in other places (like chest cavity), this indicates possible stab wounds or openings in that region

20. Additional Factors
Drugs present at the time of death can affect developmental rate of the maggots
Cocaine speeds up development
Arsenic slows development
Insects feed on toxins (removing them from body) making it difficult to test for them

21. Stomach Contents
The composition of a victim’s last meal can often provide details concerning TOD.
Used for additional sources of information as well.
Prominent case study includes Nicole Brown Simpson

22. Presence of Macromolecules can be detected
Lipids
Proteins
Simple carbohydrates
Complex carbohydrates

23. Lipids Function as long-term energy storage
Important component of the cell membrane
Consist of glycerol and fatty acid “tails”
“Tails” are long chains of carbon and hydrogen and contribute to the non-polar behavior of fats
Sudan Red is a fat-soluble dye that stains lipids red. Using Sudan red can show the amount and location of lipids

24. Both test tubes contain lipids

25. Proteins
Complex specialized molecules composed of carbon, oxygen, hydrogen, nitrogen, and sometimes sulfer
Proteins have many important roles in organisms.
Structural proteins such as collagen or elastin provide support
Regulatory proteins such as enzymes control cell processes
Buiret solution is a blue liquid that changes to purple in the presence of short chains of polypeptides
The copper atom of the biuret solution reacts with the peptide bonds to cause the color change.

26. The purple one contains protein

27. Monosaccharides and Disaccharides
Monosaccharides are simple sugars such as glucose and fructose that function as energy source in cells during cellular respiration
Disaccharides are composed of two monosaccharides together
Sucrose (table sugar) is an example of a disaccharide

28. Other Carbohydrates -- starch
Lugol’s solution -- an iodine solution used to detect starch
A dark blue color indicates starch
Large number of simple sugar molecules joined by glyosidic bonds
Produced by all plants
Consumed by humans

29. Lipid Test:

30. Protein Test

31. Glucose Test

32. Starch Test