Amy Corwin

 

 

Corpses ~ A brief summary for mystery writers

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 98.6F. Starts dropping 1 - 1.5F / 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 97.6F to 97.1F (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 94.6F to 94.1F (assuming no temperature extremes or other factors). By the end of the first 24 hours, it will probably be close to room temperature (if 78F 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 78F.  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.

 

 

   

Mystery Writers of America Member


 Facebook
Amy Corwin's Blog

Books

The Illusion of Desire

The Dead Man's View

The Vital Principle

The Earl's Masquerade

Christmas Spirit

A Rose Before Dying

A Fall of Silver

 

 

The Unwanted Heiress

 





 

Amy Corwin