forensic biology n.
Skip this Video
Loading SlideShow in 5 Seconds..
FORENSIC BIOLOGY PowerPoint Presentation
Download Presentation

play fullscreen
1 / 60


994 Views Download Presentation
Download Presentation


- - - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript


  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 • Reconstruction

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

  6. 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.

  7. Gender Determination • Pelvis best determines gender • Males have narrow pubic bone body (B)

  8. Gender determination • Females have wider subpubic angle • Females have a wider sciatic notch • Females have broader pelvic inlet

  9. Gender Determination con’t • 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)

  10. 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.

  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. 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 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. 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

  14. Racial DifferencesWhat differences do you notice between these three skulls? Could you tell each race? • Mongoloid: • wider between eyes • concave incisors • wider cheekbones • Caucasian • narrow everything • Negroid • more prominent ridges • wider nasal

  15. Determination of Age from bones • Ages 0 - 5: teeth are best-forensic 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

  16. Determination of Age from bones Occupational stress wears bones at joints Surgeries or healed wounds aid in identification

  17. Epiphysis of bones and fractures

  18. 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.

  19. 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

  20. 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-surface toward midline • D = distal-surface away from midline • O = occlusal-biting surface • F = facial-outer surface • L = lingual-surface adjacent to tongue

  21. 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 1200 2200 Porcelain melts 2200 1200 Hot fire!!

  22. ・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)

  23. 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.

  24. Steps in Facial Reconstruction 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

  25. Steps in Facial Reconstruction • 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

  26. Facial Reconstruction • Add clothing appropriate for the time period; religious affiliation or work

  27. 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.

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

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

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

  31. 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 (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

  32. 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

  33. 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.

  34. 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

  35. 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

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

  37. 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.

  38. 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

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

  40. 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

  41. 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)

  42. Life Cycle of Blow Fly

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

  44. 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.)

  45. 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.

  46. 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.

  47. 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.

  48. 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.

  49. 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.