FORENSIC BIOLOGY
Forensic Biology
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Anthropology/osteology
Odontology
Entomology
Botany
Forensic
Anthropology
Hic locus est ubi
mortui viveuntes
docent.
This is the place where
the dead teach the
living.
Anthropology
A forensic anthropologist provides basic
identification of skeletonized or badly
decomposed remains.
From a whole bone or part of a bone, the scientist
may be able to determine:
Age
 Sex
 Race
 Height
 Reconstruction
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Age Determination
Sutures
Three major cranial
sutures appear as
distinct lines in
youth and
gradually close
from the inside
out.
Age Determination
Basilar Suture
 closes in females as
young as 14
 closes in males as
young as 16
 If the suture is open,
the individual is
generally considered
18 or younger.
Gender Determination
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Pelvis best determines gender
Males have narrow pubic bone body (B)
Gender determination
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Females have wider subpubic angle
Females have a wider sciatic notch
Females have broader pelvic inlet
Gender Determination con’t
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Cranium second best
Crests & ridges more
pronounced in males (A, B, C)
Chin significantly more square
in males (E)
Jaw (I, E), mastoid process
wide and robust in males
Forehead slopes more in males
(F)
Gender Determination (cont)
Lesser Factors
The ribcage and shoulders of males are generally
wider and larger than that of females. In addition,
about one person in twenty has an extra rib. This
is more common in males than in females.
Gender Differences (cont)
Although occurring less consistently, with males the
index finger is usually shorter than the third finger.
In females, the first finger is longer than the third
finger.
Is this a male or female hand
according to the above rule?
Determination of Stature
Height of a person can be calculated by
using the length of certain bones,
including the femur, tibia, humerus,
and/or radius. Below are the average
measurements for both male and
female. There are more specific charts
if you know the race of the individual.
(All measurements are in centimeters)
Male
Female
femur x 2.23 + 69.08
tibia x 2.39 + 81.68
humerus x 2.97 + 73.57
radius x 3.65 + 80.40
femur x 2.31 +61.41
tibia x 2.53 + 72.57
humerus x 3.14 + 64.97
radius x 3.87 + 76.50
Race
Race is difficult to determine from most
skeletal remains, especially since there are
no pure races. An experienced forensic
anthropologist can generally place skulls
into one of three groups:
Caucasian
 African
 Mongoloid
Asian
American Indian
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Racial Differences
What differences do you notice between these three
skulls? Could you tell each race?
Mongoloid:
Negroid
Caucasian
 wider between eyes
more
narrow
concave
incisors
wider cheekbones
prominent ridges
wider nasal
everything
Determination of Age from bones
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Ages 0 - 5: teeth are bestforensic odontology
Ages 6 - 25: epiphyseal
fusion - fusion of ends to
bone shaft
Ages 25 - 40: very hard to
determine
Ages 40+: look for
periodontal disease,
arthritis, breakdown of
pelvis, occupational stress,
unique clues
Determination of Age from bones
Occupational stress wears bones at
joints
Surgeries or healed wounds aid in
identification
Epiphysis of bones and fractures
Odontology
Dental records: Unusual features including the number and
types of teeth and fillings, the spacing of the teeth, and/or
special dental work (bridges, false teeth, root canals) help
to make a positive identification.
Odontology and
Identification
Teeth are often used for body identification
because:
 Hardest substances in the body
 Unique to the individual
 Usually a good record of our teeth
General Teeth Information
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32 adult, permanent teeth
20 baby or deciduous teeth
Numbered from 1 to 32 starting from the upper
right (1), to upper left, to lower left to lower right
(32)
Each tooth has 5 surfaces which helps to further
individualized teeth
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M
D
O
F
L
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=
=
=
=
mesial-surface toward midline
distal-surface away from midline
occlusal-biting surface
facial-outer surface
lingual-surface adjacent to tongue
Burning
When bodies are burned, teeth and bones will
be some of the last remaining body parts.
These will be used for identification.
F
C
Teeth are brittle
400
Teeth disintegrates.
900
200
480
Cremation
1800
980
Dental gold melts
2000
2200
2200
1100
1200
BURNING RESULTS
Porcelain melts
Hot fire!!
1200
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･Oxyacetylene Flame (3000 C or above)(5432 F)
･Oxyhydrogen Flame (2000 C or above)(3632 F)
･Bunsen Burner Flame (Min. to Max. Setting) (1300 - 1600
C)(2372 - 2912 F)
･Blowtorch Flame (1300 C)(2372 F)
･Candle Flame (760 C)(1400 F)
Facial Reconstruction
To assist in identification of
unknown persons
Erasers are used to make tissue
depths at various points on the
skull. Clay is build up around
these markers and facial
features are molded.
Steps in Facial Reconstruction
Obtain a copy of a skull
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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
Steps in Facial Reconstruction
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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
Facial Reconstruction
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Add clothing
appropriate for the
time period; religious
affiliation or work
Another way to use reconstruction
John List killed his entire family
and went on the run.
Seventeen years later, Frank
Bender reconstructed what he
believed List would look like.
It was shown on America’s Most
Wanted, and he was turned in by
the viewers almost immediately.
. . looking very much like the
bust.
Anthropologist
at Work
This anthropologist is
hard at work dusting
away material from
these imbedded bones.
Picture taken at
Chicago’s Museum
of Natural History
Animal Facial Restoration
Determining what T Rex looked like using the bone formation.
From this:
To this:
Animal Structure and Function
Beaver jaw with the end
results seen on the log.
Other Bone Identification
Forensic experts may be called upon to
determine the life and death of humans and
animals in unique circumstances, including:
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Mass Murder (Oklahoma bombing, plane crashes,
World Trade)
Earlier man (mummies, Iceman, Lindow man)
Historical Significance (Holocaust, uncertain death of
famous people)
Prehistoric Animals (Dinosaurs)
Sue, the T Rex at the
Museum of Natural History
Chicago
Entomology
Entomology is the study of insects. Insects arrive at
a decomposing body in a particular order and then
complete their life cycle based on the surrounding
temperature. By collecting and studying the types
of insects found on a body, a forensic
entomologist can predict the time of death.
“When one biological clock stops, others begin.”
--Neal Haskell, reknown forensic entomologist
HISTORICALLY
1235 A.D., a Chinese death investigator named Sung
Tz’u wrote a book entitled The Washing Away of
Wrongs.
A murder, in which a sickle was used, occurred in a
Chinese village. There were no suspects, so the
investigator had all the men of the village stand in
a line with their sickles on the ground in front of
them.
Flies landed on only one sickle--the one, that
although cleaned, still had enough blood to attract
the flies. The owner then confessed.
Order of Decomposition
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Autolysis--nonbacterial;
release of gases
Putrefication--slippage of
skin, etc.
Necrophagous arthropods
Arrival depends on:
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Season or climate
Situation of the corpse--open
air, buried or in water;
geographic location; cause of
death and degree of mutilation
Changes in skin by decomposition
Decomposition
Stage
Description
Initial Decay
Carcass appears fresh externally but is
decomposing internally
Putrefaction
Carcass swollen by gas produced internally;
odor of decaying flesh
Black Putrefaction
Butyric Fermentation
Dry Decay
Flesh of creamy consistency with exposed
parts black. Body collapses as gases
escape; odor of decay very strong.
Carcass drying out. Some flesh remains;
cheesy odor develops. Ventral surface moldy
from fermentation
Carcass almost dry
Decomposition
One day old dead pig showing signs of
skin changes and bloating.
(Picture taken on June 20th, 2002)
Decomposition
Advanced stages are seen on this one
week old dead pig. As the larva develop
they migrate from the body and develop
into pupa.
Four Main Types
of Carrion Species
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Necrophagous--feed directly on the corpse
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Flies (Diptera)
Beetles (Coleoptera)
Predators
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Burying beetles (family Silphidae)
Rove beetles (family Staphylinidae)
Hister beetles (family Histeridae)
and parasites of the Necrophagous species--attract to other
animals already feeding on the body
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Order of Hymenoptera--ants, bees, and wasps
Beetles
Rove Beetle--Staphylinidae
(Lathrobium sp.)
Carrion Beetle--Silphidae
(Nicrophorus sp.)
Four Main Types
of Carrion Species (cont.)
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Species that feed on both the body and other arthropods
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Ants
Wasps
Some beetles
Arthropods that use the corpse as an extension of their
normal habitat
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Hunting spiders
Black
Green
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THE BLOW
FLY
Acts as both necrophages and as a predator.
One of the most common species on dead bodies
Often arrive within 10 minutes
Feed on any blood or fluids and then start laying
eggs in and around the natural body cavities
If the food source is exhausted, they will prey on
other species in the same genus (Chrysomya)
Life Cycle of Blow Fly
Collection
Collection are done in three ways:
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Aerial
Hand
Live Sampling
Aerial Collection
Use a net and sweep it back and
forth over the decomposing
body. Place them in a large
jar with ethyl acetate. After a
few seconds, use a funnel to
move dead flies into a vial of
75% ethyl alcohol with a label
of the date, time, case #,
location, sample type and
collector. (In this example a pig is
used as it is the closest to human in
decomposition.)
Hand Collection
Collect a variety of maggots
with forceps. Place them in
boiling water to stretch
them out and fix them.
Then place the maggots
into a vial of alcohol with
a label containing the date,
time, case #, location and
collector.
Live Sampling
“Maggot Motels”
Obtain a styrofoam container with a lid (about the size of
Chinese take-out soup). Use sand or vermiculite for the
bottom substrate. Place aluminum foil with beef or pork
liver for food on top of the substrate. Collect 10 to 15 live
maggots of varying sizes and drop them onto the foil. (You
may also harvest and develop eggs in the “motel”.) Close
the foil around them and allow to develop into pupae and
then into adults. THEY MUST BE ADULTS IN ORDER
TO IDENTIFY THE SPECIES.
Metamorphosis
Complete metamorphosis
(holometabolous)
involves development
from egg to larva to pupa
to adult. The pig ear in
the diagram to the right
shows a layer of what
looks like a white crust.
These are the fly eggs.
Larva
Larva hatch from the eggs
and increase in size by
growth steps called instars.
Eventually the larva
migrate from the corpse
and develop into an
inactive pupal stage.
During this time, the adult
insect develops internally.
Two larval instars.
PMI--Postmortem Interval
An estimation of the duration of PMI involves
setting the minimal and maximal time between
death and corpse discovery and is important in
narrowing the field of suspects.
The minimal PMI is determined largely by
estimating the age of developing immature insects
collect at the time the corpse is discovered.
The maximum PMI is determined from the species
of insects that are present and the weather
conditions necessary for the specific activity of
these species.
Body Changes
Due to Decomposition
1. When the heart stops, the
body turns pale and looks
waxy.
2. Blood settles and discolors
into a purplish red. Eyes
flatten and extremities turn
blue.
3. The appearance of burning
shows up on the drying
mucous membranes.
4. The body putrefies, turning a
greenish color. Bacteria
grows and accumulates.
5. Rot spreads and a foul odor
develops. Body bloats due to
bacterial producing gases in
the intestines.
6. Skin blisters from these
gases, detaches from the
muscles and bursts. Top
layers peel off.
7. In some circumstances, a
cheesy substance called
“adipocere” forms as fatty
tissues harden
Left alone in a warm and moist climate, a body can decompose to a skeleton within a
few weeks. In other conditions it can take months or even years.
Temperature
Ambient heat plays a role
during egg and early
larval development but
after that its effect
decreases rapidly.
Maggot masses generate
their own heat.
Taking temperature of the maggot mass
can find it as high as 125 degrees.
Maggot Mass Activity
QuickTime™ and a
YUV420 codec decompressor
are needed to see this picture.
Click on the video to
the left to observe the
maggot mass in a
decomposing pig
carcass (real time).
STOP
Continue with slides after the
Human Skeleton Lab
What do we know
about the skeleton
in the closet?
Race:
Sex:
Age:
Height:
55
What do we know
about the skeleton
in the closet?
Race: Asian
(Mongoloid)
56
What do we know
about the skeleton
in the closet?
Race: Asian (Mongoloid)
Sex: Male
57
What do we know
about the skeleton
in the closet?
Race: Asian (Mongoloid)
Sex:
Male
Age: mid 30’s
58
What do we know about
the skeleton in the
closet?
Race:
Asian (Mongoloid)
Sex:
Male
Age:
mid 30’s
Height: 5’5’’
165cm
59
What characteristics
allowed you to
make a conclusion
about race?
60