DEATH Bodies, Bugs & Bones. Back in the day … 17 th century: anyone in a coma or with a weak heartbeat was presumed dead & buried fear of being.
Post on 14-Dec-2015
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Back in the day …17th century: anyone in a coma or with
a weak heartbeat was presumed dead & buried
fear of being buried alive = cowbell in coffin (“saved by the bell”?)
“waiting mortuaries”
Death is …… cessation (end) of life?… “irreversible cessation of blood
circulation”?… cessation of all brain activity?
hard to give a single definition of – it is a PROCESS rather than an instant event
1st stage of death: STOPPAGE
heart stops cells begin to die (no O2) body processes fail (no O2) nerves, muscles, organs, brain fail
autolysis: cell breakdown
Manner of Death (MOD)natural death (most common)
- interruption/failure of body functions from age or disease
accidental death- unplanned events (car accident, falling from a ladder)
suicidal death- person purposefully kills oneself
homicidal death- death of one person caused by another
undetermined
Cause of Death (COD)the reason someone dies is the CODdisease, physical injury, stroke, heart
attack, bludgeoning, shooting, burning, drowning, strangulation, hanging, suffocation, etc.
“proximate cause of death” is an underlying cause (as opposed to the final cause)
Mechanism of Deaththe specific body change that brought
about cessation of lifeex: if COD is shooting,
mechanism may be blood loss (exsanguination) or loss of brain function
ex: if COD is a heart attack, mechanism may be heart stopping to beat or pulmonary arrest
Livor Mortis
literally means DEATH COLORRBC break down & spill contentshemoglobin turns
purple when it spillspurplish color visible
wherever blood pools (lividity)
Livor Mortis
2 hrs after death: lividity begins8 hrs after death: discoloration permanentbetween 2 and 8 hrs after death: if you press
skin, discoloration disappearsambient temp affects time for lividity to set
in (hotter = faster)can reveal approximate TOD and position of
corpse and if they’ve been moved (dual lividity)
Rigor Mortisno visible rigor:
<2 hrs or >48 hrsvery rigid (full rigor):
~12 hrsrigor only in face & neck:
just over 2 hrssome rigor in body, none in face:
more than 15 hrs ago
Rigor Mortisstiffness occurs
because skeletal muscles can’t relax (they are contracted) due to presence of extra calcium
muscles control bone movement so joints appear to be rigid too
Rigor Mortisfactors that affect rigor mortis include:
- ambient temp (warmer = faster due to faster chem reactions)- body weight (thinner = faster due to less stored O2)- type of clothing (clothed = faster)- illness (sick/fever = faster)- level of activity before death (aerobic exercise = faster)- sun exposure (sunlight = faster)
Algor Mortisliterally means DEATH HEATtemperature lossgenerally,
- lose 1.4oF per hourfor the first 12 hrs- lose 0.7oF per hourafter 12 hrs untilbody reaches tempof surroundings
Stomach & Intestinal Contents
also used to help determine TOD
4-6 hrs for stomach to empty contents into small intestine
another 12 hrs for food to leave small intestine
24 hrs for all undigested food to be released
Stages of Decompositionwithin 2 days
- cell autolysis- green/purplish staining- marbled skin- discolored face
after 4 days- skin blisters- abdomen swells with CO2
within 6 to 10 days- corpse bloats with CO2
- chest/abdominal cavities burst and collapse- fluids leak from body openings- eyeballs/other tissues liquefy- skin sloughs off
Forensic EntomologyFlies arrive within 10 minutes of deathType of insects follows a succession as
the body undergoes changes from-The fresh stage, to the bloating stage
to the dry or skeletal stage when the skin falls of leaving teeth and bone
Four development stages of flies:egg Hatch into a larva or maggotcrawls like a caterpillar and actively
consumes food to grow quickly. Maggots will pass through several
instars or stages – keep getting bigger and molt at end of every stage
Next stage: a dark immobile pupa.
adult fly emerges from pupaAdults mate, and the females will
lay more eggs onto corpses. Lays eggs in natural body openings Eggs/ worms in head area firstThen reproductive/ excretory regionsTrunk at very late stage
Insects are ectothermic-body needs to be warmed by outside to be able to grow
Will speed up process in hot climates/slow in cold regions
Drugs – cocaine will speed up life cycleDrugs – poisons (arsenic) will slow
down
Order of fliesBlow flies and flesh flies – arrives in 10
minutesBlow flies will lay eggs on corpse on
day 1Will see maggots by day 2
Image: http://www.umext.maine.edu/images/FlyLife.jpgInformation: http://www.kathyreichs.com/entomology.htm and http://www.forensicentomologist.org/
Blow Fly Metamorphosis
1st – Adult flies lay eggs on the carcass especially at wound areas or around the openings in the body such as the nose, eyes, ears, anus, etc.
2nd – Eggs hatch into larva (maggots) in 12-24 hours.
3rd– Larvae continue to grow and molt (shed their exoskeletons) as they pass through the various instar stages. 1st Instar - 5 mm long after 1.8 days 2nd Instar - 10 mm long after 2.5 days 3rd Instar – 14-16 mm long after 4-5 days
4th – The larvae (17 mm) develop into pupa after burrowing in surrounding soil.
5th – Adult flies emerge from pupa cases after 6-8 days.
Blow flies are attracted to dead bodies and often arrive within minutes of the death of an animal. They have a complete life cycle that consists of egg, larva, pupa, and adult stages.
It takes approximately 14-16 days from egg to adult depending on the temperatures and humidity levels at the location of the body.
Adult
EggsPupa
3rd Instar Larva
2nd Instar Larva
1st Instar Larva
House flies come after the flesh fly and blow fly
Will lay eggs by day 2 and maggots will be seen by day 4
The next fly to follow ONLY IN URBAN areas is the skipper fly
Will lay eggs by day 5; maggot by day 7
Fresh stage0-3 days Protein, carbs break down- Blows flies and flesh flies- no smell yetBloated stage- 3-7 days Decay starts- smell starts-
abdomen bloats due to CO2 made by bacterial respiration
House flies and predatory flies
Decay stage (putrid smell due to gas release)
8-18 days – total decay- all body bloats; abdomen breaks down – fluid seepage
Ants, cockroaches, beetlesOver 18 days – drying out phase; flesh
falls off; worms not presentMainly bugs that can feed from bones
such as beetles.
Examples of Diptera (Flies)
Informational Source: http://naturalsciences.org/files/documents/csi_tg_overview.docImages: Top Left - http://www.scienceinschool.org/repository/images/issue2forensic3_large.jpg, Middle-Left: http://forensicfact.files.wordpress.com/2008/04/blowfly053.jpg, Top Right - http://users.usachoice.net/~swb/forensics/P1.jpg, Bottom - http://www.deathonline.net/decomposition/corpse_fauna/flies/index.htm
Flesh Fly(Sarcophagidae)
Striped thorax
Blow & Greenbottle Flies(Calliphoridae)
Metallic thorax and abdomen
House Fly(Muscidae)
Cheese Skipper (Piophilidae)
Early Stage Decomposition
Late Stage Decomposition
Life Cycle of a Calliphoridae Fly
Examples of Coleoptera (Beetles)
Informational Source: http://naturalsciences.org/files/documents/csi_tg_overview.doc Images: http://www.cals.ncsu.edu/course/ent425/library/spotid/coleoptera/coleoptera.html & http://www.forensicflies.com/beetles.htm
Carrion Beetles (Silphidae)Adults & larvae feed on fly larvae
Early to Late Stage Decomposition
Late Stage Decomposition
Rove Beetles
(Staphylinidae)Predator of fly eggs
Early Stage Decomposition
Hide Beetles (Scarabidae)
Usually the last to arrive
Clown Beetles (Histeridae)
Predator of fly eggs
Ham & Checkered Beetles (Cleridae)
Predator of flies & beetles; also feed on dead tissue
Skin Beetles (Dermestidae)
Feed on dried skin & tissues
Weather data is also an important tool in analyzing insect evidence from a corpse. Investigators will make note of the temperature of the air, ground surface, the interface area between the body and the ground, and the soil under the body as well as the temperature inside any maggot masses. They will also collect weather data related to daily temperature (highs/lows) and precipitation for a period of time before the body was discovered to the time the insect evidence was collected.
Other factors that might affect their PMI estimates:
1.Was the body enclosed in an area or wrapped in a material that would have prevented flies from finding the corpse and laying eggs?
2.Were other insect species present that may have affected the development of the collected species?
3.Were there drugs or other poisons in or on the body that might have affected the larvae’s development?
Did you know…The “Body Farm” in Knoxville, Tennessee is a university research facility to investigate human decomposition under various conditions in order to understand the factors which affect its rate. Click the image to view a video
about the Body Farm!
Click the image above or click here to visit the website at http://www.pbs.org/wnet/nature/episodes/crime-scene-creatures/interactive-determine-the-time-of-death/4390/
Let’s give it a try …
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