Decomposition, Forensic Entomology, and Forensic Anthropology

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Decomposition, Forensic Entomology, and Forensic
Anthropology
http//people.stu.ca/mclaugh/skeleton8a.GIF
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Stages of Decomposition

• 1.) Initial Decay 0-3 Days
• 2.) Putrefaction 3-10 Days
• 3.) Black Putrefaction 10-20 Days
• 4.) Butyric Putrefaction 20-50 Days
• 5.) Dry Decay 50-365 Days

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Conditions That Affect Decomposition

• Air temperature/ weather conditions
• Colder slower decomposition warmer faster
  decomposition
• Clothed vs. Naked body
• Clothed slower, naked faster decomp.
• Underwaterslower decomposition
• Severe wounds faster decomp
• Insects get into body faster

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1.) Initial Decay

• 1.) Initial Decay 0 to 3 days after death
• Autolysis
• Body digested from inside outusually starts in
  pancreas
• Body relatively fresh
• Bugs start invading openings in body
• Mouth/ Eyes
• Vagina/ Anus
• Open wounds

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2.) Putrefaction

• 2.) Putrefaction 4-10 days after death
• Bacteria release gases, causes bloating
• hydrogen sulfide, methane, cadaverine, and
  putrescine
• Cells break down, release fluidsmore bugs
• More flies, beetles, and mites

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3.) Black Putrefaction

• 3.) Black Putrefaction 10-20 days after death
• Bloating collapses, tissues get creamy like
  cottage cheese
• Exposed tissue turns black
• Fluids spill into soil, bugs really start eating
  body

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4.) Butyric Fermentation

• 4.) Butyric Fermentation 20-50 days after death
• Body smells like cheese
• Body starts to dry outno more flies
• Specialized mites and beetles
• Mold grows where body touches ground

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5.) Dry Decay

• 5.) Dry Decay 50-365 days after death
• Bones and hair remain with some dried tissue
• Tinead moths and bacteria eat hair
• Bones can remain almost indefinitely
• Animals will eat and carry away bones

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Time of Death

• Rigor Mortis Stiffening of body after death
• Starts immediately
• Manifested 1-6 hours
• Maximum 6-24 hours
• Disappears 12-36 hours

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Time of Death

• Livor Mortis Settling of blood in body
• Gravity settles blood to lowest point on body, if
  on back, buttocks and shoulder blades
• Starts Immediately
• Manifested 2-4 hours
• Blood dried and settled 8-12 hours
• If a body is moved and turned over after 12
  hours, you will know the body has been moved
  post-mortem!

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Time of Death

• Algor Mortis Temperature of decomposing body
• Starts immediately and stops whenever the body
  temp reaches the ambient temp
• Remember factors that affect decomposition also
  affect algor mortis!
• Forensic scientists use the equation
• 98.4º F measured rectal temp time (hours)
• 1.5 since death

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Forensic Entomology
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Forensic EntomologyHow insects are used

• PMI Post Mortem Interval using degree day
  models and life history information
• The type of insect
• Stage of development

• Location of murder
• Species Present
• Finding an insect not generally present at body
  site suggests the body has been moved.

• Presence of drugs
• Can be sequestered in insects found on bodies

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Faunal Succession

• Sequence, pattern, and duration of insect
  activity
• Insects invade bodies in waves
• Estimation of time since death requires
• Ability to identify each species in all stages of
  their life cycles
• Knowledge of the time occupied by each life stage
  under various conditions
• Great accuracy initially, less accurate with
  increasing time
• Primarily study beetle and flies

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Succession of species
Adult
Larvae
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Faunal succession

• Linked to the natural changes which take place in
  a body after death
• After the onset of autolysis and putrefaction,
  necrophagous insects appear, depending on time of
  year and situation of cadaver
• Necrophagous insect
• ecological category for anything feeding on
  carrion
• Necrophagous insect activity accelerates
  putrefaction and the disintegration of the
  corpse.
• Gases excreted from the body (methane, ammonia,
  carbon dioxide, nitrogen) attract the insects,
  not necessarily blood.

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Faunal succession

• 1st arrival usually blowflies (within minutes)
• Females lay 200-300 eggs each (clumps of whitish
  beadlike dots, usually in orifices)
• 1-2 days later, eggs hatch1st instar maggots
• Typically there are about 3 instars of maggothood
• Pupation after about one to two weeks as a
  maggot, the outer chitin of the maggot body
  hardens, darkens, forms a shell inside of which
  the maggot metamorphizes into the beautiful adult
  fly (about a 1 week process).
• All together, blowflies emerge about 2 weeks
  after eggs are laid

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Faunal succession Beetles

• Beetles may appear during massive maggot activity
• Some beetles eat maggots
• The height of some beetle activity is after the
  first generation of flies have come and gone
• Necrophagous beetles
• Carrion beetles (Silphidae)
• Rove beetles (Staphylinidae)
• Scarab beetles (Scarabaeidae)
• Leiodid beetles (Leiodidae)

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Forensic EntomologyFlies

• Sarcophagidae - flesh flies
• Adults lay larvae on decaying flesh
• Some of the first insect to reach a corpse
• Calliphoridae blowflies
• Different species have different habits light
  vs. dark, urban vs. rural
• All have larvae that feed on corpses
• Also one of the first to arrive

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Forensic EntomologyFlies

• Strateomyidae soldier flies
• Larvae feed on human excrement and remains
• Are found late in decomposition process
• Phoridae humpbacked flies
• Larvae feed on decaying bodies
• Some species can burrow to a depth of 50cm over 4
  days
• Important in buried bodies

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Forensic EntomologyCarrion beetles

• Silphidae Carrion beetles
• Buries small carcasses
• Adults feed on maggots and carrion

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Forensic EntomologyBeetles

• Staphylinidae rove beetles
• Arrive a few hours after a death
• Are active throughout decomposition process

• Dermestids Carpet beetle
• Larvae and adults feed on dry skin and hairs

• Histeridae Hister beetles
• Found in bloated, decay, and early drying stages
• Both larvae and adults feed on maggots and puparia

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TemperatureDependent Development

• Insects are cold blooded.
• Rate of development is more or less dependent on
  ambient temperature
• For each species there is a threshold temperature
  below which no development occurs
• As temperature rises above this threshold, a
  certain amount of time is required for the insect
  to pass through each life stage.
• Because this heat is accumulated as "thermal
  units," it can be calibrated and described as
  "degree-days" or "degree-hours"

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Effect of temperature on insect development
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Forensic EntomologyCase Studies
Cannabis seized in New Zealand
The Facts

• 60 insect specimens were recovered from two
  separate cannabis seizures in New Zealand

• Only one, the rice weevil, was native to New
  Zealand

• 8 other species native only to Asia

The methods

• Plotted distributions of the 8 Asian Species

• Studied the overlap of these distributions

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Forensic EntomologyCase Studies
Cannabis seized in New Zealand -continued
The conclusions

• Cannabis originated in the Tenasserim region
  between the Andaman Sea to the west and Thailand
  in the east

• From the known habitats of insects it was
  concluded that the cannabis was harvested near a
  stream or a lake with fig trees and termite nests
  nearby

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Case study
A window next to the victim was open when the
body was found, thus giving the impression that
the murderer had forced entry into the room the
night before. However, the air conditioned room
was cool even though it was very hot outdoors. In
reality, the killer was known to the victim, had
a key, and had returned to "set the stage" by
opening the window just prior to feigning
discovery of the corpse. The insects thus had
insufficient time to colonize the body because
the window had been closed prior to the return of
the killer. When confronted by this biological
reality as pointed out by entomology, the killer
confessed.
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Why Study Bones?

• They constitute the evidence for the study of
  fossil man.
• They are the basis of racial classification in
  prehistory.
• They are the means of biological comparison of
  prehistoric peoples with the present living
  descendents.
• They bear witness to burial patterns and thus
  give evidence for the culture and world view of
  the people studied.
• They form the major source of information on
  ancient diseases and often give clues as to the
  causes of death.
• Their identification often helps solve forensic
  cases.

From "Human Osteology - A Laboratory and Field
Manual" 3rd Edition, 1987
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A Caveat

• Informative features about the age, sex, race and
  stature of individuals based on bones is based on
  biological differences between sexes and races
  (males are generally taller and more robust) as
  well as differences due to ancestry (certain
  skeletal features of the skull)
• However, it is imprecise because so much human
  variation exists and because racial differences
  tend to homogenize as populations interbreed
• Still differences do exist and the more features
  you survey, the more precise your conclusions
  will be

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What Can We Learn?

• Determination of Sex
• Pelvis
• Skull
• Determination of Race
• Skull
• Approximate Age
• Growth of long bones
• Approximate Stature
• Length of long bones
• Postmortem or antimortem injuries
• Postmortem interval (time of death)

http//en.wikipedia.org/wiki/Forensic_anthropology
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• 1. Determination of Sex
• Pelvis is the best bones (differences due to
  adaptations to childbirth)
• females have wider subpubic angle
• females have a sciatic notch gt 90
• females have a broad pelvic inlet

1.
2.
3.
2.
2.
3.
3.
1.
1.
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• 1. Determination of Sex
• Pelvis best (another view)
• females have wider subpubic angle
• females have a broad, shovel-like ilium
• females have a flexible pubic symphysis

1.
2.
3.
2.
3.
2.
1.
1.
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1. Determination of Sex Cranium

• Crests and ridges more pronounced in males (A, B,
  C)
• Chin significantly more square in males (E)
• Mastoid process wide and robust in males
• Forehead slopes more in males (F)

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1. Determination of Sex

• Normally, the long bones alone are not used alone
  to estimate gender. However, if these bones are
  the only ones present, there are characteristics
  that can be used for sex determination.
• E.g. maximum length of humerus in females is
  305.9 mm, while it is 339.0 mm in males

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Determination of Race

• It can be extremely difficult to determine the
  true race of a skeleton for several reasons
• First, forensic anthropologists generally use a
  three-race model to categorize skeletal traits
  Caucasian (European), Asian (Asian/Amerindian),
  and African (African and West Indian).
• Although there are certainly some common physical
  characteristics among these groups, not all
  individuals have skeletal traits that are
  completely consistent with their geographic
  origin.
• Second, people of mixed racial ancestry are
  common.
• Often times, a skeleton exhibits characteristics
  of more than one racial group and does not fit
  neatly into the three-race model.
• Also, the vast majority of the skeletal
  indicators used to determine race are non-metric
  traits which can be highly subjective.
• Despite these drawbacks, race determination is
  viewed as a critical part of the overall
  identification of an individual's remains.

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White, Asian, African
From Beyers, S.N. (2005). Introduction to
Forensic Anthropology
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Features of the Skull Used in Race Determination

• Nasal index The ratio of the width to the height
  of the nose, multiplied by 100
• Nasal Spine
• Feel the base of the nasal cavity, on either side
  of the nasal spine do you feel sharp ridges
  (nasal silling), rounded ridges, or no ridges at
  all (nasal guttering)?
• Prognathism extended lower jaw
• Shape of eye orbits (round or squareish

Nasal spine
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Nasal Silling and Guttering
From Beyers, S.N. (2005). Introduction to
Forensic Anthropology
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General Shapes of the Eye Orbits
From Beyers, S.N. (2005). Introduction to
Forensic Anthropology
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Determination of RaceCaucasian
Trait
Nasal Index lt.48
Nasal Spine Prominent spine
Nasal Silling / Guttering Sharp ridge (silling)
Prognathism Straight
Shape of Orbital Openings Rounded, somewhat square
http//upload.wikimedia.org/wikipedia/en/c/cc/Skul
lcauc.gif
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Determination of RaceAsian (Asian decent and
Native American decent)
Trait
Nasal Index .48-.53
Nasal Spine Somewhat prominent spine
Nasal Silling/ Guttering Rounded ridge
Prognathism Variable
Shape of Orbital Openings Rounded, somewhat circular
http//upload.wikimedia.org/wikipedia/en/b/b3/Skul
lmong.gif
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Determination of RaceAfrican (everyone of
African decent and West Indian decent)
Trait
Nasal Index gt.53
Nasal Spine Very small spine
Nasal Silling/ Guttering No ridge (guttering)
Prognathism Prognathic
Shape of Orbital Openings Rectangular or square
http//upload.wikimedia.org/wikipedia/en/5/5e/Skul
lneg.gif
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Determination of Age

• The long bones are those that grow primarily by
  elongation at an epiphysis at one end of the
  growing bone. The long bones include the femurs,
  tibias, and fibulas of the legs, the humeri,
  radii, and ulnas of the arms, and the phalanges
  of the fingers and toes.
• As a child grows the epiphyses become calcified
  (turn to hard bone)

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2. Determination of Age from Bones

• Ages 0-5 teeth are best forensic odontology
• Baby teeth are lost and adult teeth erupt in
  predictable patterns
• Ages 6-25 epiphyseal fusion fusion of bone
  ends to bone shaft
• epiphyseal fusion varies with sex and is
  typically complete by age 25
• Ages 25-40 very hard
• Ages 40 basically wear and tear on bones
• periodontal disease, arthritis, breakdown of
  pelvis, etc.
• Can also use ossification of bones such as those
  found in the cranium

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Epiphyseal Fusion A General Guide
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Epiphyseal Fusion

• The figures below are of the Epiphyses of the
  femur or thigh bone (the ball end of the joint,
  joined by a layer of cartilage).
• The lines in the illustrated Image 1 show the
  lines or layers of cartilage between the bone and
  the epiphyses. The lines are very clear on the
  bone when a person, either male or female is not
  out of puberty.
• In Image 2, you see no visible lines. This person
  is out of puberty. The epiphyses have fully
  joined when a person reaches adulthood, closing
  off the ability to grow taller or in the case of
  the arms, to grow longer.

Figure 2.
Figure 1.
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2. Determination of Age from Bone Signs of
wearing and antemortem injury
Occupational stress wears bones at joints
Surgeries or healed wounds aid in identification
http//library.med.utah.edu/kw/osteo/forensics/pos
_id/boneid_th.html
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2. Age Determination Use of Teeth
http//images.main.uab.edu/healthsys/ei_0017.gif
http//www.forensicdentistryonline.org/Forensic_pa
ges_1/images/Lakars_5yo.jpg
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3. Determination of Stature

• Long bone length (femur, tibia, humerus) is
  proportional to height
• There are tables that forensic anthropologists
  use (but these also depend to some extent on
  race)
• Since this is inexact, there are confidence
  intervals assigned to each calculation.
• For example, imagine from a skull and pelvis you
  determined the individual was an adult Caucasian,
  the height would be determine by
• Humerus length 30.8 cm
• Height 2.89 (MLH) 78.10 cm
• 2.89 (30.8) 78.10 cm
• 167 cm (56) 4.57 cm
• See your lab handout for more tables

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4. Other Information We Can Get From Bones

• Evidence of trauma (here GSW to the head)
• Evidence of post mortem trauma (here the head of
  the femur was chewed off by a carnivore)

http//library.med.utah.edu/kw/osteo/forensics/ind
ex.html
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Sources

• A very good website with photos and information
  on forensic anthropology (including estimating
  age, stature, sex and race)
• http//library.med.utah.edu/kw/osteo/forensics/ind
  ex.html
• A good site with a range of resources
• http//www.forensicanthro.com/
• Another good primer for determining informtion
  from bones
• http//www.nifs.com.au/FactFiles/bones/how.asp?pag
  ehowtitleForensic20Anthropology
• Great, interactive site
• http//whyfiles.org/192forensic_anthro/

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Lab the bones were interested in
Skull
Humerus
Pelvis
Femur
Tibia
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Sex Determination - Pelvis

• Sub-Pubic Angle
• Pubis Body Width
• Greater Sciatic Notch
• Pelvic Cavity Shape

http//mywebpages.comcast.net/wnor/pelvis.htm
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Sex Determination - Skull
Trait Female Male
Upper Edge of Eye Orbit Sharp Blunt
Shape of Eye Orbit Round Square
Zygomatic Process Not expressed beyond external auditory meatus Expressed beyond external auditory meatus
Nuchal Crest (Occipital Bone) Smooth Rough and bumpy
External Occipital Protuberance Generally Absent Generally present
Frontal Bone Round, globular Low, slanting
Mandible shape Rounded, V-shaped Square, U-shaped
Ramus of mandible Slanting Straight
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Sex Determination - Tibia
Medial Condyle
Proximal End
Lateral Condyle
Distal End
Ankle Bone
http//www.anatomyatlases.org/atlasofanatomy/plate
06/images/6-5_static.jpg
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If Youre In Doubt

• If you dont know what something is that is
  referenced in the lab
• Check to see if there is an accompanying picture
  referenced, and turn to it in your lab handout
• Try Googling either the structure (e.g.
  Wikipedia) or Google image search
• Ask Artiss
• Some skeletons have a femur and not a tibia, and
  some have a tibia and not a femur do
  appropriate measurements for whichever you have