FORENSIC BIOLOGY

Forensic Biology

Anthropology/osteology Odontology Entomology Botany

FORENSIC ANTHROPOLOGY

Hic locus est ubi mortui viveuntes docent.

This is the place where the dead teach the living.

AnthropologyA 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

Age Determination

Sutures

Three major cranial sutures appear as distinct lines in youth and gradually close from the inside out.

Age Determination

Basilar SutureTechnically 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 18 or younger.

Gender Differences in BonesThe pelvis of the female is wider. Males have a narrow

subpubic angle (A) and a narrow pubic bone body (B).

Male Female

Sub Pubic Angle

Gender Differences (cont)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?

Human StatureHeight 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 femur x 2.31 +61.41tibia x 2.39 + 81.68 tibia x 2.53 + 72.57humerus x 2.97 + 73.57 humerus x 3.14 + 64.97radius x 3.65 + 80.40 radius x 3.87 + 76.50

RaceRace 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 four groups:

Caucasian African American Asian American Indian

Racial Differences What differences do you notice between these

three skulls? Could you tell each race?

Odontology

Many times identity of a skull can be determined by comparing a person’s 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 andIdentification

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 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

M = mesial D = distal O = occlusal F = facial L = lingual

Burning

When bodies are burned, teeth and bones will be some of the last remaining body parts. These will be used for identification.

BURNING RESULTS F C

Teeth are brittle 400 200

Teeth disintegrates. 900 480

Cremation

Dental gold melts

Porcelain melts

Hot fire!!

1800 980

2000 1100

2200 1200

2200 1200

Facial RestorationAfter 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 build up around these markers and facial features are molded.

Steps in Facial ReconstructionObtain a copy of 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

Final Product

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 immediatedly. . . looking very much like the bust.

Anthropologistat Work

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

Picture taken at Chicago’s Museum of Natural History

Animal Facial RestorationDetermining 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 IdentificationForensic experts may be called upon to

determine the life and death of humans and animals in unique circumstances, including:

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 HistoryChicago

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

HISTORICALLY1235 A.D., a Chinese death investigator named Sung

Tz’u wrote a book entitled The Washing Away of Wrongs. It contained one of the first accounts of the use of insects as forensic evidence. 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.

Decomposition

Stage Description

Initial Decay

Putrefaction

Black Putrefaction

Butyric Fermentation

Dry Decay

Carcass appears fresh externally but is decomposing internally

Carcass swollen by gas produced internally; odor of decaying flesh

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.

Order of Decomposition Autolysis--nonbacterial;

release of gases Putrefication--slippage of

skin, etc. Necrophagous arthropods

Arrival depends on: 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

Four Main Types of Carrion Species

Necrophagous--feed directly on the corpse Flies (Diptera) Beetles (Coleoptera)

Predators 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

Order of Hymenoptera--ants, bees, and wasps

Beetles

Carrion Beetle--Silphidae (Nicrophorus sp.)

Rove Beetle--Staphylinidae (Lathrobium sp.)

Four Main Types of Carrion Species (cont.)

Species that feed on both the body and other arthropods Ants Wasps Some beetles

Arthropods that use the corpse as an extension of their normal habitat

Hunting spiders

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)

Black

Green

Collection

Collection are done in three ways: Aerial Hand Live Sampling

Aerial CollectionUse 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 IntervalAn 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 ChangesDue 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

Click on the video to the left to observe the maggot mass in a decomposing pig carcass (real time).

QuickTime™ and a decompressor

are needed to see this picture.