Unit 8 – Decomposition & Human Remains

Mrs. TeatesForensic Science

Newport High School

Lesson 1 – Stages of Death

• Lesson Essential Questions:– What are the stages of death?

Vocabulary:Algor mortis, glaister equation, livor mortis, rigor

mortis, autolysis, putrefaction, adipocere, saponification, diagenesis

Rigor Mortis

• Skeletal muscles partially contract• Joints stiffen, lock in place• Onset is 10 minutes to several hours• Rapid cooling can delay it• Lasts up to 72 hours

Chemistry of Rigor Mortis

• Living muscle cells use oxygen to burn glycogen• After death no oxygen—anaerobic glycosis makes

lactic and pyruvic acids• pH falls as acidity increases• Acid promotes a reaction between actin and myosin

which work together to contract the muscle• Muscle shortens until all ATP and acetylcholine is

used up

Muscle Contraction

End of Rigor Mortis

• The muscles relax when the body starts to decompose and the fibers begin to break down

• Intracellular digestive enzymes are released from the lysosomes as the cells begin to disintegrate, destroying the muscle fibers (autolysis)

• Meat is more tender after rigor mortis has passed (Aged Beef?)

Temperature Dependence of Rigor Mortis

Rigor depends on:

• the type of muscle fibers

•Temperature

•Stiffen faster at higher temperature

Studies of rigor development in ratshttp://www.geradts.com/anil/ij/vol_003_no_002/papers/paper001/002.gif

Livor Mortis

• Heart stops beating which had been mixing blood

• Red blood cells are denser so they sink• Maroon to blue color develops at lowest

points• Visible 30 minutes-2 hours after death• Tells you if the body was moved.

Livor Mortis

• Soon after death, blood is still in vessels, so pressure on an area pushes the bood out

• As time goes on blood vessels break down as do blood cells and hemoglobin break down pigment moves out into the tissues

• Pressure or constrictive clothing prevents blood from pooling locally– Contact pallor

Livor Mortis

Livor Mortis

• After death cells release enzyme (fibrinolysins) that prevents clotting

• Blood in body stays liquid after death– Permanently won’t clot 30-60 minutes after death

Algor Mortis

• Body cools by – Radiation

• (the higher the body temperature the more heat lost)

– Conduction depends on surface contact• faster if in water because enhanced contact

– Convection• Wind cools faster

• Rate of cooling of body after death– 1.5 °F per hour under “normal conditions”– No real conditions are “normal”

Algor Mortis

• Ambient temperature– Newton’s Law of Cooling

• T is body temperature, t is time• The bigger the temperature difference, the faster the

cooling rate• Outdoors, temperature varies a lot—must correct

formula by varying Tambient

( )( ( ) )ambient tT k T t Tt

Algor Mortis

• If ambient temperature is constant, Newton’s Law of Cooling is easy to solve

• Measure temperature at two different times without moving the body to find k

0( ) ( ) ktambient ambientT t T T T e

Algor Mortis

70

80

90

100

0 2 4 6 8 10 12 14Time Since Death (hrs)

Bo

dy

Tem

per

atu

re (

F)

Ambient T

Body T

Algor Mortis

• Clothing – Insulates body from heat loss

• Obesity– Fat insulates, temperature falls more slowly

• Ratio of surface area to volume– Children, thin people cool faster

• In water?– Cooling is faster since water is a better conductor

of heat than air

Approximate Times for Algor and Rigor Mortis

.

Algor Mortis

• New issue– Is there a plateau before body temperature starts

to fall after death?– May be up to several hours– Anaerobic cellular chemistry continues after death– Cellular chemistry releases energy as heat

Testing Potassium Levels in the Eye to Determine Time of Death

• K concentration is higher inside cells by up to 40X during life

• It takes energy (ATP) to maintain the difference

Maintaining Concentration Difference in a Living Cell

Potassium in Ocular Fluid

• At death, no more ATP formation (energy storage molecule)

• K diffuses out of cells at a constant rate, into fluid inside the eye

• Time of death

• Most accurate in first 12 hours after death• Supposedly independent of temperature

7.14 39.1vt K

Determining Long Post Mortem Intervals

• Decomposition occurs in stages– Initial Decay (0-3 days)

• Autolysis--body’s own enzymes destroys tissue• Begins immediately

– Putrefaction (4-10 days)• Bacteria in gut leak out• Anaerobic conditions• Bloat from hydrogen sulfide, methane, cadaverine,

putrescine released

The Smell of DeathThe Smell of Death

putrescinecadaverine

Breakdown products from amino acids ornithine and lysineAmino acid loses CO2

H = white C = turquoise N = blue

Determining Long Post Mortem Intervals

– Black Putrefaction (10-20 days)• Body collapses• Liquid seeps into the soil

– Butyric Fermentation (20-50 days)• Cheesy smell from butyric acid• Maggots leave• Beetles arrive

– Dry decay (beyond 50 days)• Hair is consumed by moths and mites• Bones are left

Longer Term Estimates of Time of Death

• Monitoring ratios of body decay products in the soil

Dr. ArpadVass, ORNL

The Body FarmU. Tenn.

The first well controlled experiments to explore decomposition

Identifying Small Molecules

• Gas chromatography– Presumptive test

• Gas chromatography + mass spectrometry– Definitive test

• We will discuss these techniques in detail later in the course!

Volatile Fatty Acid AnalysisResults from the Body Farm

• Depends on temperature– The hotter, the faster the reactions proceed– Accumulated Degree Days (sum average daily temp)– Decay is linear in Accumulated Degree Days

• Depends on whether body was buried or not– Decay is faster on the surface

• More insect activity• Warmer—2 feet down is fairly constant 50-55o F

• Decay is slower in acid soil– Pine forests have very acid soil

• Decay is slower if the body is sprayed with insecticide

Adipocere—Grave Wax

• On bodies are not exposed to insects• Requires moist anaerobic environment (drowning)• Hydrolysis of fat to fatty acids and soaps in presence

of bacterial enzymes• Basic conditions enhance formation• Prominent on cheeks, buttocks, stomach, breasts• Resistant to bacteria

– Slows further decomposition

Otzi, the Ice Man

• 5300 year old body• Found by hikers in Austrian Alps• Otzi is primarily now adipocere

www.spectroscopynow.com/.../MS_Feb08_otzi.jpg

The Process of Death, continued

Stage Description

Initial or fresh decay (autolysis)The cadaver appears fresh externally but is decomposing internally due to the activities of bacteria present before death (0–4 days).

Putrefaction or bloatingThe cadaver is swollen by gas produced internally, accompanied by the odor of decaying flesh (4–10 days).

Black putrefaction

Flesh of creamy consistency, with exposed body parts black. Body collapses as gases escape. Fluids drain from body. Odor of decay very strong (10–20 days).

Butyric fermentationCadaver drying out. Some flesh remains at first; cheesy odor from butyric acid (20–50 days).

Dry decay (diagenesis)Cadaver almost dry; slow rate of decay. May mummify (50–365 days).

Summary of Stages of Death

98.4°F – internal body temperature 1.5

Hours since death =

The Process of DeathAlgor Mortis: Body cooling rate

Livor Mortis: skin discoloration caused by pooling of blood

Rigor Mortis: rigidity of skeletal muscles

A pathologist estimates time of death from these factors.

Temperature of body Stiffness of body Time since death

Warm Not stiff Not dead more than 3 hours

Warm Stiff Dead between 3 and 8 hours

Cold Stiff Dead between 8 and 36 hours

Cold Not stiff Dead for more than 36 hours

Summary of Decomposition

Lesson 2 – Forensic Entomology

• Lesson Essential Questions:– How is the life cycle of insects important in

determining the time of death?– How do insects play a role in decomposition?

Vocabulary:Metamorphosis, molt, instar, oviposition, ambient,

mites, eclosion, degree-day, puparia

TaxonomyClassification of Things in an Orderly Way

We are interested in the phylum, Arthropoda; class, Insecta; order:

Diptera (flies) Coleoptera (beetles)

Forensic Entomology•Entomology is the study of insects.•Forensic entomology involves the use of insects and other arthropods to aid in legal investigation•There are three areas of application:

•Insect damage to structures•Infestation of foodstuffs•Insects that inhabit human remains

Life Cycle of InsectsMetamorphosis

egg

larva (maggot)

pupa

winged adult

The life cycle of Musca domestica

Insects arrive at a decomposing body in a particular order (succession) and then complete their life cycle based on the surrounding temperature. By collecting and studying the types of insects found on a body and their metamorphic stage, a forensic entomologist can estimate the time of death.

Time of Death

Accumulated Degree Hours and Days

• Accumulated degree hour (ADH): a given amount of thermal energy needed to develop from one stage of an insect life cycle to the next

• Degree day – amount of development that occurs in 24 hours

• Accumulated degree day (ADD): a given amount of days that an insect requires to complete its development.– Unique to different species of insects

• ADH and ADD are calculated from temperature data.

Calculating ADD

1. Calculate the mean (average) temperature for that day.

2. Compare the mean to the organism’s lower developmental threshold.

3. If the mean is three degrees higher than the lower developmental threshold, then there have been three degree-days.

(Developmental thresholds need to be looked up for individual insects.)

Calculating ADH

• Calculate degree days and then multiple by 24. This is an approximate value.

Insects of Death

DipteraFirst to arrive Then

Blowflies Flesh flies Houseflies

Flies can arrive within minutes. They lay eggs that hatch to maggots. Maggots feed on soft, mushy body parts. More insects arrive to feed on the body and each other.

Insects of Death, continued

ColeopteraIn rough order of appearance, from within hours to dry decay:

Rove beetle Sexton beetle Clown beetle Dermestid beetle Hide beetle

Some beetles feed on the corpse, some on maggots, some on other beetles.

Variables Affecting Metamorphosis

Temperature

The higher the temperature (within limits), the faster the growth.

Variables Affecting Metamorphosis, continued

Habitat

Fly species can vary geographically according to climate, season, and habitat.

For example, the fly pictured on the left prefers shade; the one on the right, sunlit areas.

Phormia regina Lucilia illustris

Collection of Evidence

Lesson 3 – The Skeleton & Skeletal Remains

• Lesson Essential Questions:– Why is it important for forensic scientists to know

the bones of the human skeleton?

Vocabulary:Forensic anthropology, osteology, oseons

Forensic Anthropology

•Forensic anthropology is a type of applied anthropology that specializes in the changes and variations in the human skeleton for the purpose of legal inquiry.•A forensic anthropologist may provide basic identification information on skeletonized or badly decomposed remains.•From a whole bone or part of a bone, the scientist may be able to determine:

•Age•Sex•Race•Approximate height•Cause of death

Osteology

Osteology is the study of bones.

There are 206 bones in an adult human.

Function of bones:• Provide structure and rigidity • Protect soft tissue and organs• Serve as an attachment for muscles• Produce blood cells• Serve as a storage area for minerals• Can detoxify the body by removing heavy metals

and other foreign elements from the blood

Classifying Bones

• Long bones – longer than they are wide; include bones in the arms, legs, hands, and feet

• Short bones – approximately as long as they are wide; they are found in the wrist and ankle

• Flat bones – Flat and enclose soft organs; they include most bones in the skill and the scapula, sternum, hip bones, and ribs

• Irregular bones – irregularly shaped; they include the vertebrae and some of the bones in the skull

Identifying Bones

• Use the worksheet to identify the major bones in the body.

Lesson 4 – Determination of Characteristics from Remains

• Lesson Essential Questions:– How can sex, gender, age, and race be

determined from the skeleton?

Vocabulary: femur, tibia, humerus

Estimation of Height• The height of a person can be calculated by measuring the

length of certain long bones, including the femur, tibia, humerus, and radius.

• Below are the equations used to determine average measurements for both male and female. (All measurements are in centimeters.)

Male Height, H

H = femur 2.23 + 69.08H = tibia 2.39 + 81.68H = humerus 2.97 + 73.57H = radius 3.65 + 80.40

Female Height, H

H = femur 2.21 + 61.41H = tibia 2.53 + 72.57H = humerus 3.14 + 64.97H = radius 3.87 + 73.50

Determining Height of an Individual

Age Determination

• Most accurate estimations are made from:• Teeth• Epiphyses or growth plates• Pubic symphysis• Cranial sutures: The three major cranial sutures appear as

distinct lines in youth and gradually close from the inside out.

• Investigators always use an age range because of the variation in people and how they age.

• The investigator does not want to eliminate any possibilities for identification.

Age Determination Using Cranial SuturesSagittal suture completely closed

Male—26 or olderFemale—29 or older

Sagittal suture completely openMale—less than 32Female—less than 35

Complete closure of all three major suturesMale—over 35Female—over 50

Sagittal suture

Lambodial Coronal

Age Determination Using Basilar Suture

Basilar suture

Technically known as the synchondrosis spheno-occipitalis, closes in females as young as 14 and in males as young as 16. If the suture is open, the individual is generally considered to be 18 or younger.

Age Determination

• In long bones, the diaphysis makes up most of the bone’s length. • The epiphyses are found at the ends of the bones; their function is to allow

for growth. (Good places to estimate changes in age.)• Though all people are different there are similarities that allow for

generalizations in estimating age.Stage 1: no epiphysis (the growth plate has not formed yet)

Stage 2: non-union; the epiphysis and bone are separate

Stage 3: partial union; the epiphysis is attached, but a line is visible

Stage 4: complete union; the epiphysis is attached and a line is not visible

The Medial Clavicle in Stages 1–4

Stage of Unionof Medial Clavicle

Male Female

Non-union without separate epiphysis

21 or younger 20 or younger

Non-union with separate epiphysis

16–21 17–20

Partial union 17–30 17–33

Complete union 21 or older 20 or older

Gender Differences in Bones• Determination of sex is crucial to the analysis

of unidentified human remains.• The pelvis offers the most definitive traits.• Comparison of three characteristics of the os

pubis gives the information used to identify sex.

Determination of Sex

Gender Identification

A. The female (top) has a wider pubic body than the male (bottom).

B. The female has a wider subpubic concavity or subpubic angle.

C. Most females have a ventral arc present.

Male Female

Subpubic Angle18

Human Remains

Determine which are male and which are female. On page 420 in the textbook.

Other ways to determine sex of the individual

• The rib cage and shoulders of males are generally wider and larger than those of females.

• In addition, about one person in 20 has an extra rib.

• This is more common in males than in females.

• In males, the index finger is sometimes shorter than the third finger. In females, the index finger is sometimes longer than the third finger. This is not often used as an indicator of gender, as there are many exceptions.

Gender Differences

• The rib cage and shoulders of males are generally wider and larger than those of females.

• In addition, about one person in 20 has an extra rib.

• This is more common in males than in females.

Race• Race is difficult to determine from most skeletal remains, especially

since pure races are becoming uncommon.

• An experienced forensic anthropologist can generally place skulls into one of three groups:

• Caucasoid—European, Middle Eastern, and Indian descent

• Negroid—African, Aborigine, and Melanesian descent

• Mongoloid—Asian, Native American, and Polynesian descent

Determining Race

Caucasoids—have a long, narrow nasal aperture, a triangular palate, oval orbits, narrow zygomatic arches, and narrow mandibles.

Negroids—have a wide nasal aperture, a rectangular palate, square orbits, and more pronounced zygomatic arches. The long bones are longer, and have less curvature and greater density.

Mongoloids—have a more rounded nasal aperture, a parabolic palate, rounded orbits, wide zygomatic arches, and more pointed mandibles.

What differences do you notice among these three skulls? Can you determine race?

OdontologyThe Study of Teeth

• The identity of an individual can be determined by comparing a person’s teeth to his or her dental records.

• Unusual features including the number and types of teeth and fillings, the spacing of the teeth, and/or special dental work help to make a positive identification.

Teeth are often used for body identification because:

They are the hardest substances in the body (they do not readily decompose).

They are unique to the individual.

X rays are a good record of a person’s teeth, giving them a unique identity.

Using Teeth to Determine Identity

Facial Restoration• After determining the sex,

age, and race of an individual, facial features can be built upon a skull to assist in identification.

• Erasers are used to make tissue depths at various points on the skull.

• Clay is used to build around these markers, and facial features are molded.

Facial Reconstruction

Steps in Facial Reconstruction

With a skull:Establish age, sex, and race.Plot landmarks for tissue

thickness.Plot origin and insertion points

for muscles.Plot landmarks for facial

features.Select a dataset and mount

markers for tissue thickness.Mount the eyes.

Model muscles on skull.Add fatty tissue around

eyes and lacrimal glands.

Add eyelids.Add the nose.Add the parotid gland.Add the ears.Cover all with layers of

skin.Detail the face.

Animal Facial Restoration

Determining what T. Rex looked like using the bone formation.

From this: To this:

More Applications

Forensic experts may be called uponto give information on the life and deathof humans and animals in uniquecircumstances, including:

• Mass murder (Oklahoma bombing, plane crashes, World Trade Center)

• Earlier man (mummies, Iceman, Lindow Man)

• Historical significance (Holocaust, uncertain death of famous people)

• Prehistoric animals (dinosaurs)

The Body Farm was created to help forensic experts with this task.

The Body Farm• The Body Farm is the nickname of a two-and-a-half-

acre research facility in Tennessee developed in 1980 by Bill Bass where bodies are placed in various conditions and allowed to decompose.

• Its main purpose is to observe and understand the processes and timetable of postmortem decay.

• Over the years it has helped to improve the ability to determine “time since death” in murder cases.

Hic locus est ubi mortui viveuntes docent.

“ This is the place where the dead teach the living.”

Case Study: Facial Reconstruction

John List killed his entire family, moved to a new town, and assumed a new identity. Seventeen years later, Frank Bender reconstructed what he believed List would look like. The reconstruction was shown on America’s Most Wanted, and he was turned in by the viewers almost immediately . . . looking very much like the reconstruction.

Check out more about this story on truTV’s Crime Library:

www.crimelibrary.com/notorious_murders/family/list/1.html

Case Study

Anthropologist at Work

This anthropologist ishard at work dustingaway material from these embedded bones.

Picture taken at Chicago’s Museum of Natural History