Presentation on theme: "STAGES OF DECOMPOSITION"— Presentation transcript:
1STAGES OF DECOMPOSITION WARNING…. GRAPHIC MATERIALSTAGES OF DECOMPOSITIONMrs. MacWilliamsCSI Forensic Science
2DEATH 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 deathenvironmental factors (like rain or temperature).These factors affect when algor mortis, rigor mortis, and livor mortis occurs and when the body begins to decay.
3Algor mortis Algor mortis = cooling of body temperature after death. Begins immediately after death metabolism in body tissues stopsMeasuring internal body temperature for indication of time of deathNEWTON’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
4RIGOR MORTISStiffening of the muscles due to lactic acid build up after somatic deathMuscle cells are still alive, contract, produce stiffening effectRigor mortis usually occurs about 2-3 hours after deathAround 36 hours after the onset of rigor mortis, the body again relaxes and is pliable
5LIVOR MORTISPooling of blood in the body due to gravity after heart stopsAppears on skin as purplish-red discolorationCan give indication of body position at time of deathDoes not happen in areas that are in contact with the ground or other objectsBegins within ½ hour after death and most evident in first 12 hoursWill not move regardless of how body is disturbed
6THE LIVING PIG A live pig is not outwardly decomposing intestines contains bacteria, protozoans, and nematodesSome of these micro-organism are ready for a new life, should the pig die and lose its ability to keep them under control.
7THE 5 STAGES OF DECAYFive stages of decay each stage attracts its own set of insectsSuccession is what aides the forensic entomologist in determining the time of deathAKA Post Mortem Interval or PMI
8Stage 1: Initial Decay 0-3 days after death State of decayAfter death, bacteria in intestine begin to digest the intestine itself, break out of the intestine and digest surrounding internal organsBody's own digestive enzymes spread through the body, contributing to its decompositionEnzymes inside cells are released and break down the cell and its connections with other cellsAKA“Fresh Stage”
9Stage 1: Initial Decay 0-3 days after death Insect activityFlies 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
10Stage 2: Putrefaction - 4 to 10 days after death State of decayBacteria break down tissues and cells, releasing fluids into body cavitiesproduce various foul smelling gases that are very attractive to a variety of insectsBuild up of gas, creates pressure within the body and inflates the body, forcing fluids out of cells and blood vessels, into the body cavityAKA“BLOAT STAGE”
11Stage 2: Putrefaction - 4 to 10 days after death Insect activitymaggots move throughout the body, spreading bacteria, secreting digestive enzymes and tearing tissues with their mouth hooksMove as a maggot mass benefiting from communal heat and shared digestive secretionsSmells and body fluids begin to attract more blowflies, flesh flies, beetles and mitesLater-arriving flies and beetles are predators, feeding on maggots as well as the decaying fleshParasitoid wasps lay their eggs inside maggots and pupae.
12Stage 3: Black putrefaction - 10 to 20 days after death State of decayBloated body eventually collapses, becomes flatExposed parts are black in color and have very strong smell of decayLarge volume of body fluids drain from the body at this stage seep into the surrounding soilOther insects and mites feed on this materialInsects consume bulk of fleshbody temperature increases with their activityBacterial decay is still very importantwill eventually consume the body if insects are excluded
13Stage 3: Black putrefaction - 10 to 20 days after death Insect activitySeveral 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 pupaePredatory maggots are much more abundant and flies cease to be attracted to the corpsePredatory beetles lay their eggs in the corpse and their larvae hatch out and feed on the decaying fleshParasitoid wasps laying their eggs inside maggots and pupae
14Stage 4: Butyric fermentation - 20 to 50 days after death State of decayRemaining flesh is removed over this period and the body dries outcheesy smell caused by butyric acidsmell attracts a new suite of corpse organismssurface of the body in contact with ground becomes covered with mold as the body ferments
15Stage 4: Butyric fermentation - 20 to 50 days after death Insect activityBeetles feed on the skin and ligaments.Beetle larvae hatch from eggs which fed on the body in earlier stages of decayCheese fly consumes any remaining moist flesh at this stage, even though it is uncommon earlier in decayPredators and parasitoids are still present at this stage including numerous wasps and beetle larvae
16Stage 5: Dry decay - 50-365 days after death State of decay Body is now dry and decays very slowlyEventually all the hair disappears leaving only the bones
17Decompostion of a Baby Pig Pictures fromJust for fun… MAGGOT CHEESE!!! Would you eat this??? Maggot cheese video