Let me state immediately that I am not an authority on corpses, or a
medical doctor, or anyone who might be considered knowledgeable about
corpses. Other than the fact that I was a biology student eons ago,
perhaps. However, I've collected information I use when writing
mysteries. I'm presenting it here on a "for what it is worth" basis.
My second qualification is this: there are no
hard-and-fast rules. If there were, medical examiners, coroners and
the like would have no difficulties determining time of death. So
everything presented here is a generality. Weather conditions, the
placement of the body, wrappings, habits of the deceased (Did they use
drugs? Were they overweight? Did they have an infection?) and
other factors will influence how, and how fast, decomposition occurs.
As you read this, you will see some "timeline issues"
but they are due to issues such as "in a lab setting" versus "left in a more
natural setting". There are no hard and fast rules and as you pass
certain marks such as the 4 hour mark and 1 day mark, things start getting a
little mushy depending upon the circumstances of the corpse. (Pun
intended.) A natural setting, insects, and summer weather will speed up the process. An urban setting and cool, winter weather will
delay the process. But note, there will still be insects in an
urban setting (although perhaps not in the winter). The urban insects
simply may not be the same ones, and they may have less
access to the body depending upon the circumstances. If insects have
less access, the bloating and decomposition may take longer.
However, these guidelines may still be useful,
particularly for "cozy" mystery writers who don't delve too deeply into the
intricate, complex decomposition and decay processes. On the right
hand side of this page, I've also offered a selection of books which I have
found to be very useful.
Warning: This is gross and disgusting.
So enough. Let's get down to business of corpse
presentation and decomposition.
Time
Body
Condition
Notes
Case Study: Insects & A Body Outdoors in Summer (in NC)
Pre-mortem & Point of
Death
Body Appearance:
if eyes are open, they will "glaze over" and appear to "flatten" as a
thin film forms on the surface. Skin will become pale and waxy in
appearance. Urine and feces may be expelled.
Algor mortis / temperature:
Normal/alive is 98.6°F. Starts
dropping 1 - 1.5°F / hour until it
reaches room temperature.
Rigor mortis: body is
initially limp, however, a cadaveric spasm may cause
immediate stiffness of hands & arms, for example if the victim is
gripping a gun or other object.
Food Digestion:
Notoriously unreliable. A light
meal may take 2 hours to be digested. A heavy meal may take 4-6
hours. So you can sometimes backtrack from the state of the contents of
the stomach to the point when the victim was alive to ingest & digest the food.
Many things affect this including: metabolism, emotions, exercise, etc,
so it is hard to use this except "roughly". The small intestines
are often examined, however, for information.
Insects: Some blow flies
will alight and begin to lay eggs even before death. Eggs will be
laid in the wound area and around openings (moist orifices) such as
nostrils, mouth, eyes, and ears.
Algor mortis factors:
If it is cold, the temperature drops more quickly. Obese people
cool more slowly. Clothing can insulate the body. Exercise
immediately before death and some drugs may raise the temperature or
keep it from cooling at the expected rate.
Insects: Insect
species will vary by time of year (e.g. winter/summer) and location
(geographical as well as habitat). However, you
can use a general name, e.g. greenbottle fly, in place of a specific
species, e.g. Lucilia ceasar because the specific species of
greenbottle will vary from place to place.
Digestion: Don't forget that after death, ingested food
will decay along with the body.
Death occurs
outside, in a field, during the morning on a clear, summer day.
No mammalian or avian scavengers present.
Morning
Immediately: flesh flies (mostly Sarcophaga spp.) lay eggs
around nostrils, eyes, mouth, umbilical cord and anus.
1 Hour to 3 Hours
post-mortem
Body Appearance:
if eyes are open, they will appear cloudy and flattened. Extremities
turn blue shortly after death. Skin is pale and waxy in appearance.
Ocular Indicators:
Potassium (vitreous potassium) from the breakdown of red blood cells
enters the eyes 2-3 hours after death.
Algor mortis: At 1 hour
post-mortem, temperature will be around 97.6°F
to 97.1°F (assuming no
temperature extremes or other factors).
Livor
mortis: postmortem lividity or discoloration of the skin appears 1-2
hours after death. If the lividity blanches when touched (pressure
is applied) then lividity is not fixed so it has been more than 2 hours
but less than 10 since death. Lividity is caused by red blood
cells settling in the lowest parts of the body--the discoloration will
be deep purple and usually found closest to the ground.
Rigor mortis: Somewhere
between 15 minutes to 15 hours after death, the body stiffens. The
average is 2-3 hours. Stiffness first appears in the face, jaw &
neck, then spreads over the next 18 hours through the body.
Stiffness lasts up to 36 hours.
Decomposition: The
injured area(s) decay more quickly because they will be one of the first
sites to attract insects.
Insects: Blow flies and
Flesh flies will alight and begin to lay eggs. Eggs will be laid
in the wound area and around openings (particularly moist orifices) such
as nostrils, mouth, eyes, and ears.
Decomposition
Generalities:
warm/moist -
quickest--decomp to skeleton in a few weeks
hot/dry - may
mummify instead of "normal" decomposition
water - a body
immersed in water will be preserved nearly twice as long as in open air
(unless eaten by crabs or other scavengers, of course)
burial -
extends decomp time by several weeks
Livor
mortis: Substances such as carbon monoxide can keep blood bright
red. Bodies which have suffered acute blood loss will not
discolor. *Livor mortis is often used as a clue to the body being
moved.
Rigor mortis: Heat speeds
up rigor mortis stiffness. Obese victims may fail to
stiffen at all.
Afternoon
A variety of blow flies and screwworms (Cochliomyia macellaria)
arrive on the corpse, including:
Greenbottle flies: Phaenicia coeruleiviridis
Black Blow flies: Phormia regina
Slightly later, wasps arrive including:
Yellow Jackets: Vespula maculifrons
Hornets: Vespula maculata
Soon after the wasps, the ants arrive (Formica spp.)
4 Hours to 1 Day
post-mortem
Body Appearance:
desiccation (the appearance of burning) will begin to show on mucus
membranes as they dry. Bloating will begin in the lower abdomen. The
body is stiff.
Algor mortis: At 4 hour
post-mortem, temperature will be around 94.6°F
to 94.1°F (assuming no
temperature extremes or other factors). By the end of the first 24
hours, it will probably be close to room temperature (if 78°F
is room temperature).
Livor
mortis: postmortem lividity or discoloration of the skin is evident,
but the area will still blanch when touched (pressure is applied) if it
is less than 10 since death.
By 8-10 hours, lividity is fixed in
the parts of the body lowest/nearest to the ground, post-mortem.
Rigor mortis: The body
should be be stiffening or stiff. Stiffness first appears in the face,
jaw & neck, then spreads over the next 15-18 hours through the body.
Stiffness lasts up to 36 hours.
Decomposition: The
injured area(s) will be affected by insects. Bloating will begin
in the lower abdomen as bacteria spread. Bacterial activity
produces gas which causes the bloat and a foul odor.
Insects: Blow flies and
Flesh flies are joined by screwworms, wasps and ants. By the 16th hour,
some maggots may have already hatched.
Insects:
Greenbottle fly eggs can take 13 hours to hatch in 78°F.
If death occurs in the summer at 7am, it is possible for the first eggs
to hatch by 8pm that evening if the day has been warm and it is still
light until past 8pm.
Eggs
will take longer to hatch in the cold night air since insect activity
diminishes or ceases during night, cold, or overcast periods.
Only corpses buried in the
winter are free of blow fly eggs. (Interesting trivia.)
Late
Afternoon of Day 1
Later in the afternoon, decay fluids begin
to drip and this draws houseflies (Musca domestica) to feed on
the fluids.
Night
Most insects will become inactive during the cooler, night
temperatures.
2 to 3 Days
post-mortem
Body Appearance:
Skin shows greenish discoloration. Bloating in the lower abdomen spreads
to thighs and chest. The chest will swell and the face becomes
unrecognizable. Frothy fluids may leak from the mouth & anus.
By the third day, the body is
bloated, a foul odor is present, and the skin goes black.
At 3 days to 1 week,
the skin is loose and easily slips from fingers, hands & limbs.
Algor mortis: By now, the body
will be "room temperature" or even a little warmer as bacterial activity
generates some heat.
Livor
mortis: postmortem lividity or discoloration of the skin is fixed.
Rigor mortis: The body
should be be stiff unless there are other factors such as obesity.
Stiffness lasts up to 36 hours. After that point, the body looses
stiffness in the same order, i.e. face & neck loosen up first. It
takes another 10 hours (or so) for the body to become completely limp
again.
Decomposition: The
injured area(s) will be affected by insects. Bloating is underway
in the lower abdomen, thighs, and chest as bacteria spread.
Bacterial activity produces gas which causes the bloat and a foul odor.
Insects: Adult Blow flies
and Flesh flies are gone. Their larvae are activity feeding on the
face, belly & genitals.
Second Day Body enters bloat stage.
Blow & Flesh fly activity continues.
Other insects appear:
Cheese skippers (Piophila casei)
Fruit & Vinegar flies (Drosophila spp.)
By afternoon of the 2nd day, frothy fluids leak from the mouth & anus
Bloat continues for 2 days.
Third Day Adult Blow & Flesh flies are gone. Their larvae are
feeding on the face, belly & genitals.
4 Days to 1
Week post-mortem
Body Appearance:
Skin is black and begin to be dried out. The corpse will be bloated
unless the activity of the insects caused the
release of internal gases and the corpse "deflated". Decay
liquids will soak into the ground or underlying surface (e.g. carpet or
whatever).
At 3 days to 1 week,
the skin is loose and easily slips from fingers, hands & limbs.
Algor mortis: The body is "room
temperature".
Livor
mortis: postmortem lividity or discoloration of the skin is
fixed--if it is still recognizable any longer due to other changes.
Rigor mortis: The body
should be be limp again--what there is left of it. Depending upon
conditions, it may be fully limp at 6-8 days.
Decomposition: Bacterial
activity is well advanced and may already be dying down as the body
liquefies. A smell more reminiscent of acetone may be present.
Insects: Maggots are hard
at work or even finishing. Other insects including butterflies,
moths, and bees may be present.
Bloating:
Various factors affect this, including insects. If they don't
rupture the abdominal cavity and release the gases building up from
bacterial activity, bloating may last much longer. (See next
section.)
Bodies in Water:
A submerged body (or a body in other special conditions) will form a
cheesy substance called adipocere as the fatty tissues harden.
This will keep a body preserved.
Fourth Day Active decay stage. Fly larvae break into the abdominal
cavity, releasing gases. The body deflates. Decay liquids
saturate the ground.
The decay liquids draw the following insects:
Rove beetles (Platydracus spp.)
Clown beetles (Hister spp.)
These beetles burrow beneath the body.
Horseflies are drawn to the smells.
Fifth Day Active decay stage. Packs of maggots move through chest
and the abdominal cavity.
The body seems to "liquefy".
The decay liquids draw butterflies, moths and bees.
Sixth Day Advanced decay. Most soft tissue is gone. Maggots
start leaving the body and beetles attack the maggots.
Seventh Day Advanced decay. Body looks dried out. Enters dry
decay stage. Looks like a mass of bones, cartilage and dried skin.
New insects arrive:
Skin beetles: Dermestes spp.
Hide beetles: Trox spp.
Checkered beetles: Necrobia spp.
2 Weeks
post-mortem
Body
Appearance: Bloating by the 2nd week makes the tongue, breasts,
scrotum & eyes protrude. Intestines are often pushed out through
the rectum.
Skin blisters from the gases, detaches from the muscles &
bursts. The top layers peel off.
The internal organs break open & liquefy.
The body starts purging fluids from orifices.
Teeth, hair & nails become loose.
Of course, these things assume insects, animals and warm weather
didn't hasten the process.
The bloating
period may need to be shortened and/or moved back to an earlier period
if the body is left in a more natural setting. Bloating may occur
as early as the second day and be pretty much done by the sixth day.
Rest of the
Summer
A slow disintegration occurs through the rest of the
summer, leaving a mat of hair, bleached bones, teeth and bits of dry
skin.
Only millipedes and centipedes live around the bones now. And maybe a
few spiders and ants.
Actual case from 1850--How Insects Solved the Case
The desiccated
corpse of an infant was discovered hidden in a building in 1850. The
authorities needed to determine if the child belonged to the current
tenants or the previous tenants.
Upon examination, two generations of insects were found on the
corpse.
Eggs of larvae found in March 1850 must have been laid in the
middle (summer) of 1849. These were the eggs of moths which prefer a
dried out corpse.
In addition to living larvae, many pupae were present and they had
to come from eggs laid earlier in 1848. These were deposited by Flesh
flies who prefer a fresh corpse.
If the body was there earlier in 1846-7, there would not have been
larvae since they would have hatched.
So the body could not been there earlier than the spring of 1848.
Insects are not active during winter months and Flesh flies would not
have been interested in a body already dried out as it would have been
if it had been entombed in the winter of 1847.
Therefore, the body had to have been hidden in the spring of 1848.
Two generations of insects indicated that 2 years had passed,
post-mortem, and it was the previous tenants who had killed and hidden
their infant child, not the current tenants.
As you can see from this example, you have to allow for the
seasons as well as other factors. Cold, winter months are not
conducive to insect activity.
