Presentation on theme: "Unit 8 – Decomposition & Human Remains Mrs. Teates Forensic Science Newport High School."— Presentation transcript:
Unit 8 – Decomposition & Human Remains Mrs. Teates Forensic Science Newport High School
Lesson 1 – Stages of Death Lesson Essential Questions: – What are the stages of death? Vocabulary: Algor mortis, glaister equation, livor mortis, rigor mortis, autolysis, putrefaction, adipocere, saponification, diagenesis
Rigor Mortis Skeletal muscles partially contract Joints stiffen, lock in place Onset is 10 minutes to several hours Rapid cooling can delay it Lasts up to 72 hours
Chemistry of Rigor Mortis Living muscle cells use oxygen to burn glycogen After death no oxygen—anaerobic glycosis makes lactic and pyruvic acids pH falls as acidity increases Acid promotes a reaction between actin and myosin which work together to contract the muscle Muscle shortens until all ATP and acetylcholine is used up
End of Rigor Mortis The muscles relax when the body starts to decompose and the fibers begin to break down Intracellular digestive enzymes are released from the lysosomes as the cells begin to disintegrate, destroying the muscle fibers (autolysis) Meat is more tender after rigor mortis has passed (Aged Beef?)
Temperature Dependence of Rigor Mortis Rigor depends on: the type of muscle fibers Temperature Stiffen faster at higher temperature Studies of rigor development in rats
Livor Mortis Heart stops beating which had been mixing blood Red blood cells are denser so they sink Maroon to blue color develops at lowest points Visible 30 minutes-2 hours after death Tells you if the body was moved.
Livor Mortis Soon after death, blood is still in vessels, so pressure on an area pushes the bood out As time goes on blood vessels break down as do blood cells and hemoglobin break down pigment moves out into the tissues Pressure or constrictive clothing prevents blood from pooling locally – Contact pallor
After death cells release enzyme (fibrinolysins) that prevents clotting Blood in body stays liquid after death – Permanently won’t clot minutes after death
Algor Mortis Body cools by – Radiation (the higher the body temperature the more heat lost) – Conduction depends on surface contact faster if in water because enhanced contact – Convection Wind cools faster Rate of cooling of body after death – 1.5 ° F per hour under “normal conditions” – No real conditions are “normal”
Algor Mortis Ambient temperature – Newton’s Law of Cooling T is body temperature, t is time The bigger the temperature difference, the faster the cooling rate Outdoors, temperature varies a lot—must correct formula by varying T ambient
Algor Mortis If ambient temperature is constant, Newton’s Law of Cooling is easy to solve Measure temperature at two different times without moving the body to find k
Clothing – Insulates body from heat loss Obesity – Fat insulates, temperature falls more slowly Ratio of surface area to volume – Children, thin people cool faster In water? – Cooling is faster since water is a better conductor of heat than air
Approximate Times for Algor and Rigor Mortis.
Algor Mortis New issue – Is there a plateau before body temperature starts to fall after death? – May be up to several hours – Anaerobic cellular chemistry continues after death – Cellular chemistry releases energy as heat
Testing Potassium Levels in the Eye to Determine Time of Death K concentration is higher inside cells by up to 40X during life It takes energy (ATP) to maintain the difference
Maintaining Concentration Difference in a Living Cell
Potassium in Ocular Fluid At death, no more ATP formation (energy storage molecule) K diffuses out of cells at a constant rate, into fluid inside the eye Time of death Most accurate in first 12 hours after death Supposedly independent of temperature
Determining Long Post Mortem Intervals Decomposition occurs in stages – Initial Decay (0-3 days) Autolysis--body’s own enzymes destroys tissue Begins immediately – Putrefaction (4-10 days) Bacteria in gut leak out Anaerobic conditions Bloat from hydrogen sulfide, methane, cadaverine, putrescine released
The Smell of Death putrescine cadaverine Breakdown products from amino acids ornithine and lysine Amino acid loses CO 2 H = white C = turquoise N = blue
Determining Long Post Mortem Intervals – Black Putrefaction (10-20 days) Body collapses Liquid seeps into the soil – Butyric Fermentation (20-50 days) Cheesy smell from butyric acid Maggots leave Beetles arrive – Dry decay (beyond 50 days) Hair is consumed by moths and mites Bones are left
Longer Term Estimates of Time of Death Monitoring ratios of body decay products in the soil Dr. Arpad Vass, ORNL The Body Farm U. Tenn. The first well controlled experiments to explore decomposition
Identifying Small Molecules Gas chromatography – Presumptive test Gas chromatography + mass spectrometry – Definitive test We will discuss these techniques in detail later in the course!
Volatile Fatty Acid Analysis Results from the Body Farm Depends on temperature – The hotter, the faster the reactions proceed – Accumulated Degree Days (sum average daily temp) – Decay is linear in Accumulated Degree Days Depends on whether body was buried or not – Decay is faster on the surface More insect activity Warmer—2 feet down is fairly constant o F Decay is slower in acid soil – Pine forests have very acid soil Decay is slower if the body is sprayed with insecticide
Adipocere—Grave Wax On bodies are not exposed to insects Requires moist anaerobic environment (drowning) Hydrolysis of fat to fatty acids and soaps in presence of bacterial enzymes Basic conditions enhance formation Prominent on cheeks, buttocks, stomach, breasts Resistant to bacteria – Slows further decomposition
Otzi, the Ice Man 5300 year old body Found by hikers in Austrian Alps Otzi is primarily now adipocere
The Process of Death, continued StageDescription Initial or fresh decay (autolysis) The cadaver appears fresh externally but is decomposing internally due to the activities of bacteria present before death (0–4 days). Putrefaction or bloating The cadaver is swollen by gas produced internally, accompanied by the odor of decaying flesh (4–10 days). Black putrefaction Flesh of creamy consistency, with exposed body parts black. Body collapses as gases escape. Fluids drain from body. Odor of decay very strong (10–20 days). Butyric fermentation Cadaver drying out. Some flesh remains at first; cheesy odor from butyric acid (20–50 days). Dry decay (diagenesis) Cadaver almost dry; slow rate of decay. May mummify (50–365 days). Summary of Stages of Death
98.4°F – internal body temperature 1.5 Hours since death = The Process of Death Algor Mortis: Body cooling rate Livor Mortis: skin discoloration caused by pooling of blood Rigor Mortis: rigidity of skeletal muscles A pathologist estimates time of death from these factors. Temperature of bodyStiffness of bodyTime since death WarmNot stiffNot dead more than 3 hours WarmStiffDead between 3 and 8 hours ColdStiffDead between 8 and 36 hours ColdNot stiffDead for more than 36 hours Summary of Decomposition
Lesson 2 – Forensic Entomology Lesson Essential Questions: – How is the life cycle of insects important in determining the time of death? – How do insects play a role in decomposition? Vocabulary: Metamorphosis, molt, instar, oviposition, ambient, mites, eclosion, degree-day, puparia
Taxonomy Classification of Things in an Orderly Way We are interested in the phylum, Arthropoda; class, Insecta; order: Diptera (flies) Coleoptera (beetles)
Forensic Entomology Entomology is the study of insects. Forensic entomology involves the use of insects and other arthropods to aid in legal investigation There are three areas of application: Insect damage to structures Infestation of foodstuffs Insects that inhabit human remains
Life Cycle of Insects Metamorphosis egg larva (maggot) pupa winged adult The life cycle of Musca domestica
Insects arrive at a decomposing body in a particular order (succession) and then complete their life cycle based on the surrounding temperature. By collecting and studying the types of insects found on a body and their metamorphic stage, a forensic entomologist can estimate the time of death. Time of Death
Accumulated Degree Hours and Days Accumulated degree hour (ADH): a given amount of thermal energy needed to develop from one stage of an insect life cycle to the next Degree day – amount of development that occurs in 24 hours Accumulated degree day (ADD): a given amount of days that an insect requires to complete its development. – Unique to different species of insects ADH and ADD are calculated from temperature data.
Calculating ADD 1.Calculate the mean (average) temperature for that day. 2.Compare the mean to the organism’s lower developmental threshold. 3.If the mean is three degrees higher than the lower developmental threshold, then there have been three degree-days. (Developmental thresholds need to be looked up for individual insects.)
Calculating ADH Calculate degree days and then multiple by 24. This is an approximate value.
Insects of Death Diptera First to arrive Then Blowflies Flesh flies Houseflies Flies can arrive within minutes. They lay eggs that hatch to maggots. Maggots feed on soft, mushy body parts. More insects arrive to feed on the body and each other.
Insects of Death, continued Coleoptera In rough order of appearance, from within hours to dry decay: Rove beetleSexton beetle Clown beetle Dermestid beetle Hide beetle Some beetles feed on the corpse, some on maggots, some on other beetles.
Variables Affecting Metamorphosis Temperature The higher the temperature (within limits), the faster the growth.
Variables Affecting Metamorphosis, continued Habitat Fly species can vary geographically according to climate, season, and habitat. For example, the fly pictured on the left prefers shade; the one on the right, sunlit areas. Phormia reginaLucilia illustris
Collection of Evidence
Lesson 3 – The Skeleton & Skeletal Remains Lesson Essential Questions: – Why is it important for forensic scientists to know the bones of the human skeleton? Vocabulary: Forensic anthropology, osteology, oseons
Forensic Anthropology Forensic anthropology is a type of applied anthropology that specializes in the changes and variations in the human skeleton for the purpose of legal inquiry. A forensic anthropologist may provide basic identification information on skeletonized or badly decomposed remains. From a whole bone or part of a bone, the scientist may be able to determine: Age Sex Race Approximate height Cause of death
Osteology Osteology is the study of bones. There are 206 bones in an adult human. Function of bones: Provide structure and rigidity Protect soft tissue and organs Serve as an attachment for muscles Produce blood cells Serve as a storage area for minerals Can detoxify the body by removing heavy metals and other foreign elements from the blood
Classifying Bones Long bones – longer than they are wide; include bones in the arms, legs, hands, and feet Short bones – approximately as long as they are wide; they are found in the wrist and ankle Flat bones – Flat and enclose soft organs; they include most bones in the skill and the scapula, sternum, hip bones, and ribs Irregular bones – irregularly shaped; they include the vertebrae and some of the bones in the skull
Identifying Bones Use the worksheet to identify the major bones in the body.
Lesson 4 – Determination of Characteristics from Remains Lesson Essential Questions: – How can sex, gender, age, and race be determined from the skeleton? Vocabulary: femur, tibia, humerus
Estimation of Height The height of a person can be calculated by measuring the length of certain long bones, including the femur, tibia, humerus, and radius. Below are the equations used to determine average measurements for both male and female. (All measurements are in centimeters.) Male Height, H H = femur H = tibia H = humerus H = radius Female Height, H H = femur H = tibia H = humerus H = radius Determining Height of an Individual
Age Determination Most accurate estimations are made from: Teeth Epiphyses or growth plates Pubic symphysis Cranial sutures: The three major cranial sutures appear as distinct lines in youth and gradually close from the inside out. Investigators always use an age range because of the variation in people and how they age. The investigator does not want to eliminate any possibilities for identification.
Age Determination Using Cranial Sutures Sagittal suture completely closed Male—26 or older Female—29 or older Sagittal suture completely open Male—less than 32 Female—less than 35 Complete closure of all three major sutures Male—over 35 Female—over 50 Sagittal suture LambodialCoronal
Age Determination Using Basilar Suture Basilar suture Technically 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 to be 18 or younger.
Age Determination In long bones, the diaphysis makes up most of the bone’s length. The epiphyses are found at the ends of the bones; their function is to allow for growth. (Good places to estimate changes in age.) Though all people are different there are similarities that allow for generalizations in estimating age. Stage 1: no epiphysis (the growth plate has not formed yet) Stage 2: non-union; the epiphysis and bone are separate Stage 3: partial union; the epiphysis is attached, but a line is visible Stage 4: complete union; the epiphysis is attached and a line is not visible
The Medial Clavicle in Stages 1–4 Stage of Union of Medial Clavicle MaleFemale Non-union without separate epiphysis 21 or younger20 or younger Non-union with separate epiphysis 16–2117–20 Partial union17–3017–33 Complete union21 or older20 or older
Gender Differences in Bones Determination of sex is crucial to the analysis of unidentified human remains. The pelvis offers the most definitive traits. Comparison of three characteristics of the os pubis gives the information used to identify sex. Determination of Sex
Gender Identification A. The female (top) has a wider pubic body than the male (bottom). B. The female has a wider subpubic concavity or subpubic angle. C. Most females have a ventral arc present.
Male Female Subpubic Angle 18 Human Remains
Determine which are male and which are female. On page 420 in the textbook.
Other ways to determine sex of the individual The rib cage and shoulders of males are generally wider and larger than those of females. In addition, about one person in 20 has an extra rib. This is more common in males than in females. In males, the index finger is sometimes shorter than the third finger. In females, the index finger is sometimes longer than the third finger. This is not often used as an indicator of gender, as there are many exceptions.
Gender Differences The rib cage and shoulders of males are generally wider and larger than those of females. In addition, about one person in 20 has an extra rib. This is more common in males than in females.
Race Race is difficult to determine from most skeletal remains, especially since pure races are becoming uncommon. An experienced forensic anthropologist can generally place skulls into one of three groups: Caucasoid—European, Middle Eastern, and Indian descent Negroid—African, Aborigine, and Melanesian descent Mongoloid—Asian, Native American, and Polynesian descent Determining Race Caucasoids—have a long, narrow nasal aperture, a triangular palate, oval orbits, narrow zygomatic arches, and narrow mandibles. Negroids—have a wide nasal aperture, a rectangular palate, square orbits, and more pronounced zygomatic arches. The long bones are longer, and have less curvature and greater density. Mongoloids—have a more rounded nasal aperture, a parabolic palate, rounded orbits, wide zygomatic arches, and more pointed mandibles.
What differences do you notice among these three skulls? Can you determine race?
Odontology The Study of Teeth The identity of an individual can be determined by comparing a person’s teeth to his or her dental records. Unusual features including the number and types of teeth and fillings, the spacing of the teeth, and/or special dental work help to make a positive identification. Teeth are often used for body identification because: They are the hardest substances in the body (they do not readily decompose). They are unique to the individual. X rays are a good record of a person’s teeth, giving them a unique identity. Using Teeth to Determine Identity
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 used to build around these markers, and facial features are molded. Facial Reconstruction
Steps in Facial Reconstruction With 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.
Animal Facial Restoration Determining what T. Rex looked like using the bone formation. From this: To this:
More Applications Forensic experts may be called upon to give information on the life and death of humans and animals in unique circumstances, including: Mass murder (Oklahoma bombing, plane crashes, World Trade Center) Earlier man (mummies, Iceman, Lindow Man) Historical significance (Holocaust, uncertain death of famous people) Prehistoric animals (dinosaurs) The Body Farm was created to help forensic experts with this task.
The Body Farm The Body Farm is the nickname of a two-and-a-half- acre research facility in Tennessee developed in 1980 by Bill Bass where bodies are placed in various conditions and allowed to decompose. Its main purpose is to observe and understand the processes and timetable of postmortem decay. Over the years it has helped to improve the ability to determine “time since death” in murder cases. Hic locus est ubi mortui viveuntes docent. “ This is the place where the dead teach the living.”
Case Study: Facial Reconstruction John List killed his entire family, moved to a new town, and assumed a new identity. Seventeen years later, Frank Bender reconstructed what he believed List would look like. The reconstruction was shown on America’s Most Wanted, and he was turned in by the viewers almost immediately... looking very much like the reconstruction. Check out more about this story on truTV’s Crime Library: tml Case Study
Anthropologist at Work This anthropologist is hard at work dusting away material from these embedded bones. Picture taken at Chicago’s Museum of Natural History