TIME OF DEATH

TIME OF DEATH

Forensic science provides a number of solutions to solving the mystery question of when a person died.

The longer it has been since the death, the less accurate the estimation given by forensic pathologists.

1. BODY TEMPERATURE• The core body temperature drops at an estimated

rate of 1oC each hour from the time of death.• Factors affecting this estimation:

Temperature at the scene of crimeHumidity levelsAir movementFat levels in the bodyetc

• The liver is our largest organ, so Scene of Crime Officers measure core body temperature from here.

Can you read the temperature on this thermometer? It is 38oCCan you read the temperature on this thermometer? It is 38oC

ACTIVITY 1a) What would you expect the

body temperature to be 5 hours after death? (Hint: See red line on graph)

b) What would you expect the body temperature to be 10 hours after death?

c) If the deceased has a core body temperature of 35 degrees Celsius, how long has the person been dead for?

d) Why do you think the temperature stops dropping at 24 degrees Celsius? Explain.

2. HARDENING• Stiffening of the corpse occurs between just 30 minutes and 3 hours

after death. The process is called rigor mortis • Occurs as the muscles in the body begin to stiffen from a lack of

blood and oxygen. • After the first stiffening of eyelids and jaws of the victim are

observed, rigor mortis spreads throughout the whole body in approximately 6 to 12 hours, before receding again after another 6 to 12 hours.

3. THE TRUTH LIES IN THE EYES• A thin cloudy film is developed over the eye within 3 hours

after death has occurred. Pupils dilate (get larger)• The eyeballs become softer as a result of less fluid pressure

behind the eye and the degree to which this has occurred can be used as a measure of the time since death

• When you do your squid dissection, notice the cloudiness in the eyes of the squid.

4. SKIN COLOUR• Straight after death, the body turns a whitish grey colour.• About 48 hours after death, bacteria begins to breed on the skin,

giving the skin a greenish tone. The tinge starts in the lower stomach area, spreading outwards and affecting the hands and feet last.

• About 4-7 days after death, the skin will acquire a marble-like appearance, as the veins in the body become closer to the surface, thus becoming more easily visible.

Pig Sample 1 Pig Sample 2 Pig Sample 3

ACTIVITY 2Place the skin colour samples of pigs in the following order:Alive, 48 hours after death, 4-7 days after death.

5. BLOOD POOLING• The pooling of the blood can be a vital clue

in determining the time of death and is known as hypostasis.

• This occurs when the blood ceases flowing, settling in the lowest parts of the body and in turn, causing the skin to become pink and red in colour.

• This process is complete in up to 6 hours after death.

• Blood pooling can also help us determine the manner of death.

6. THE DIGESTIVE SYSTEM

2-4hrs

5-6hrs

12-24hrs

ACTIVITY 3A corpse of a sponge was found washed up on a nearby beach at 8:00am today. The victim was identified by Mr Partick Star to be that of Mr SpongeBob SquarePants. Mr SquarePants is known to have the same digestive system typical of the human species.

Witnesses say they saw Mr SquarePants eating at Krusty Krab around 7:00pm yesterday.

Upon examination of Mr SquarePants’ stomach contents, masticated and partially digested Krabby patty burgers were discovered. What information can you provide investigators with?

7. FORENSIC ENTOMOLOGY

is the use of the insects, and their arthropod relatives that

inhabit decomposing remains to aid legal investigations.

An arthropod is an invertebrate animal having an exoskeleton (external skeleton), a segmented body, and jointed appendages.

MAGGOTS (Larvae)ACTIVITY 4Use the following slide to work out how long this potato had been rotting on the ground.

ACTIVITY 4Use the following slide to work out how long this potato had been rotting on the ground.

Adult flies attracted to moist areas and decaying matter. Adults live 3 to 4 weeks.

3 to 4 days

8 to 12 hours

Larvae produced. These feed on protein and grow rapidly. At the end of the growth phase, larvae move to a drier place to pupate

4 to 7 days

3 to 4 days