STAGES OF DECOMPOSITIONSTAGES OF DECOMPOSITION

Mrs. MacWilliamsCSI Forensic Science

WARNING…. GRAPHIC MATERIAL

DEATH• Two types of death: somatic and cellular. • Somatic death occurs when the individual is irreversibly

unconscious- what we consider “dead.” • This does not mean all functions immediately cease.

• After somatic death, the body’s cellular processes continue. • Time frame for this continuance varies according to many

things like:• type of cell (blood, tissue, organ, etc)• trauma to the cells (like a stab wound or drowning)• activity level before death• environmental factors (like rain or temperature).

• These factors affect when algor mortis, rigor mortis, and livor mortis occurs and when the body begins to decay.

Algor mortis• Algor mortis = cooling of body temperature after death.• Begins immediately after death metabolism in body

tissues stops• Measuring internal body temperature for indication of

time of death• NEWTON’s Law of Cooling = rate of change of the

temperature of an object is proportional to the difference between its own temperature and the ambient temperature.– Hours since death = (98.4°F – internal body temperature) ÷ 1.5

RIGOR MORTIS• Stiffening of the muscles due to lactic acid build up

after somatic death • Muscle cells are still alive, contract, produce

stiffening effect• Rigor mortis usually occurs about 2-3 hours after

death• Around 36 hours after the onset of rigor mortis,

the body again relaxes and is pliable

LIVOR MORTIS• Pooling of blood in the body due to gravity after

heart stops• Appears on skin as purplish-red discoloration• Can give indication of body position at time of

death• Does not happen in areas that are in contact with

the ground or other objects• Begins within ½ hour after death and most evident

in first 12 hours• Will not move regardless of how body is disturbed

THE LIVING PIG• A live pig is not

outwardly decomposing • intestines contains

bacteria, protozoans, and nematodes

• Some of these micro-organism are ready for a new life, should the pig die and lose its ability to keep them under control.

THE 5 STAGES OF DECAY• Five stages of decay each stage attracts its own

set of insects• Succession is what aides the forensic entomologist

in determining the time of death– AKA Post Mortem Interval or PMI

Stage 1: Initial Decay 0-3 days after death

State of decay•After death, bacteria in intestine begin to digest the intestine itself, break out of the intestine and digest surrounding internal organs•Body's own digestive enzymes spread through the body, contributing to its decomposition

• Enzymes inside cells are released and break down the cell and its connections with other cells

• AKA“Fresh Stage”

Stage 1: Initial Decay 0-3 days after death

Insect activity•Flies are attracted to bodies. •Blowflies and house flies are able to lay eggs around wounds and natural body openings (mouth, nose, eyes, anus, genitalia) •Eggs hatch and move into the body, often within 24 hours. •Life cycle of a fly from egg to maggot to fly takes from two to three weeks longer at lower temperatures

Stage 2: Putrefaction - 4 to 10 days after death

State of decay•Bacteria break down tissues and cells, releasing fluids into body cavities•produce various foul smelling gases that are very attractive to a variety of insects

• Build up of gas, creates pressure within the body and inflates the body, forcing fluids out of cells and blood vessels, into the body cavity

AKA “BLOAT STAGE”

Stage 2: Putrefaction - 4 to 10 days after death

Insect activity•maggots move throughout the body, spreading bacteria, secreting digestive enzymes and tearing tissues with their mouth hooks •Move as a maggot mass benefiting from communal heat and shared digestive secretions•Smells and body fluids begin to attract more blowflies, flesh flies, beetles and mites•Later-arriving flies and beetles are predators, feeding on maggots as well as the decaying flesh•Parasitoid wasps lay their eggs inside maggots and pupae.

Stage 3: Black putrefaction - 10 to 20 days after death

State of decay•Bloated body eventually collapses, becomes flat•Exposed parts are black in color and have very strong smell of decay•Large volume of body fluids drain from the body at this stage seep into the surrounding soil•Other insects and mites feed on this material

• Insects consume bulk of flesh • body temperature increases with

their activity• Bacterial decay is still very

important• will eventually consume

the body if insects are excluded

Stage 3: Black putrefaction - 10 to 20 days after death

Insect activity•Several generations of maggots are present on the body and some have become fully grown. •Migrate from the body and bury themselves in the soil where they become pupae•Predatory maggots are much more abundant and flies cease to be attracted to the corpse•Predatory beetles lay their eggs in the corpse and their larvae hatch out and feed on the decaying flesh•Parasitoid wasps laying their eggs inside maggots and pupae

Stage 4: Butyric fermentation - 20 to 50 days after death

State of decay•Remaining flesh is removed over this period and the body dries out•cheesy smell caused by butyric acid•smell attracts a new suite of corpse organisms•surface of the body in contact with ground becomes covered with mold as the body ferments

Stage 4: Butyric fermentation - 20 to 50 days after death

Insect activity•Beetles feed on the skin and ligaments. •Beetle larvae hatch from eggs which fed on the body in earlier stages of decay•Cheese fly consumes any remaining moist flesh at this stage, even though it is uncommon earlier in decay•Predators and parasitoids are still present at this stage including numerous wasps and beetle larvae

Stage 5: Dry decay - 50-365 days after death

State of decay Body is now dry and decays very slowly

Eventually all the hair disappears leaving only the bones

• Decompostion of a Baby Pig

• Pictures from http://deathonline.net/decomposition

• Just for fun… MAGGOT CHEESE!!! Would you eat this??? Maggot cheese video