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FORENSIC BIOLOGY

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. Anthropology.

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FORENSIC BIOLOGY

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  1. FORENSIC BIOLOGY

  2. Forensic Biology • Anthropology/osteology • Odontology • Entomology • Botany

  3. FORENSIC ANTHROPOLOGY Hic locus est ubi mortui viveuntes docent. This is the place where the dead teach the living.

  4. 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

  5. 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

  6. 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 = oclusal • F = facial • L = lingual

  7. 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 BURNING RESULTS 400 200 Teeth are brittle 900 480 Teeth disintegrates. 1800 980 Cremation 2000 1100 Dental gold melts 2200 2200 Porcelain melts 2200 2200 Hot fire!!

  8. Gender Differences in Bones The pelvis of the female is wider. Males have a narrow subpubic angle (A) and a narrow pubic bone body (B). B A

  9. Male Female Sub Pubic Angle

  10. 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.

  11. 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?

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

  13. Animal Structure and Function Beaver jaw with the end results seen on the log.

  14. 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 four groups: • Caucasian • African American • Asian • American Indian

  15. Racial Differences What differences do you notice between these three skulls? Could you tell each race?

  16. 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 build up around these markers and facial features are molded.

  17. Obtain 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 Steps in Facial Reconstruction

  18. Facial Landmarks www.raka.co.za/anthropology/ faces/index.html

  19. Animal Facial Restoration Determining what T Rex looked like using the bone formation. From this: To this:

  20. Other Bone Identification Forensic experts may be called upon to determine the life and death of humans and animals in unique circumstances, including: • Mass Murder (bombs, 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

  21. Anthropologistat Work This anthropologist is hard at work dusting away material from these imbedded bones. Picture taken at Chicago’s Museum of Natural History

  22. Ondontology 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.

  23. Botany Plants can be used in forensic investigations if they are unique to an area or if they have unique characteristics, such as pollen, seeds, petals, etc.

  24. 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

  25. HISTORICALLY 1235 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.

  26. Decomposition Stage Description Carcass appears fresh externally but is decomposing internally Initial Decay Carcass swollen by gas produced internally; odor of decaying flesh Putrefaction Flesh of creamy consistency with exposed parts black. Body collapses as gases escape; odor of decay very strong. Black Putrefaction Carcass drying out. Some flesh remains; cheesy odor develops. Ventral surface moldy from fermentation Butyric Fermentation Carcass almost dry; Dry Decay

  27. Decomposition One day old dead pig showing signs of skin changes and bloating. (Picture taken on June 20th, 2002)

  28. 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.

  29. 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

  30. 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

  31. Beetles Carrion Beetle--Silphidae (Nicrophorus sp.) Rove Beetle--Staphylinidae (Lathrobium sp.)

  32. 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

  33. THE BLOW FLY Black Green • 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)

  34. Collection Collection are done in three ways: • Aerial • Hand • Live Sampling

  35. 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.)

  36. 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.

  37. 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.

  38. 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.

  39. 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.

  40. 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.

  41. Death Fresh Bloat Active Decay Biomass Loss Advanced Decay Putrid Biomass Loss Advanced Decay Putrid Dry or Skeletal Remains Decomposition Time Line

  42. 1. When the heart stops, the 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 Body ChangesDue to Decomposition 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.

  43. Basic Assumptions • Most homicides occur at night when flies flies are presumably inactive. • Flies being ovipositing (laying eggs) as soon as they discover the body. • Faunal succession in and under the corpse will follow a predictable pattern. • Ambient air temperatures are the major factors influencing the rate of maggot development From Entomology and Death by Catts and Haskell; 1990

  44. 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.

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

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