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Analyses of Different Aspects of Forensic Science Areas

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  1. 1. TERMINOLOGY Pathology is the study of disease, so forensic pathology is the study of injuries and/or disease in order to determine the cause of death. Involves the investigation of sudden, unnatural, unexplained, or violent deaths. Typically these are the medical examiners or coroners A medical examiner who works for the legal system to determine cause of death in legal cases. They conduct autopsies to determine not only the ultimate cause of death but also the manner and mode of death. Answer questions: who is the victim, what injuries are present, when did the injuries occur, why and how were the injuries produced, and what is the cause of death
  2. 2. BEFORE AN AUTOPSY - A MEDICAL EXAMINER WILL SEARCH FOR ANY PHYSICAL EVIDENCE ON THE BODY • Conditional Evidence – lividity, rigor mortis, odors, insects, position, clothing. • Pattern Evidence – bite marks, imprints, impressions, weapon marks, insertions, injuries, wounds. • Biological Evidence – grass, leaves, wood, plants, pollen, flowers, insects, worms, etc. • Chemical Evidence – cosmetics, firearms, vehicle-related chemicals, drugs, alcohol, poisons, ink, oil, cleaning fluids, soil, glass. • Physiological Evidence – blood, semen, urine, fecal materials, tears, milk, bile, tissues, bone, hair.
  3. 3. DEATH Cause of Death • Asphyxiation – Strangulation – Drowning – Fire victim • Exsanguination - Major blood loss • Blunt force trauma • Sharp force trauma • Chemical trauma • Heart failure • Gun Shot • Decapitation Manner of Death • Natural: 80 year old dies of congestive heart failure • Homicide: death caused by another person • Suicide: death inflicted upon self • Accidental: unintentional and without malice, group swimming and one drowns • Undetermined: absolute cause not able to be determined
  4. 4. BODY TEMPERATURE • Normal body temperature is 98.6˚F • one hour after death, the body cools at a rate of 0.78°C (1.4°F) per hour. After • the first 12 hours, the body loses about 0.39°C (0.7°F) per hour. • In 24 hours the body is at external temperature • Several days after death Putrefaction (bacteria in the body release gases causing body to become bloated) occurs and body temp can rise to 127˚F
  5. 5. ESTIMATED TIME OF DEATH • Rigor Mortis (“rigor” = stiffness, “mortis” = of death): medical condition that occurs after death and results in the shortening of muscle tissue and the stiffening of body parts in the position they are in when death occurs. • Begins ~4 hours after death • Stiffening of body because of lack of oxygen in muscle cells • Begins in eyelids and small muscles of jaw, then to neck and rest of body • Is spread up by increased external temp and slowed down by cooler temp • Sets in more slowly with overweight individuals • Sets in more quickly when there has been a violent struggle (uses up energy in muscles) • Completely sets in within 12 hours after death and lasts ~36 hours before body returns to non-rigid state
  6. 6. ESTIMATED TIME OF DEATH • Livor Mortis or lividity: medical condition that occurs after death and results in the settling of blood in areas of the body closest to the ground. • Discoloration of skin after death • Caused by gravity-induced stagnation and settling of red blood cells in small blood vessels • Commonly referred to as “lividity” • Begins immediately after death and lasts for 12 hours. • Occurs in parts of body closest to ground (gravity!)
  7. 7. ESTIMATED TIME OF DEATH Algor Mortis (“algor” = coldness “Mortis” = of death): postmortem changes that cause a body to lose heat. Process in which the body continues to cool to room temperature. 1 – 1.5 degree/hour. Effects that influence Algor Mortis are: • Temperature of the surrounding environment • Type of clothing on the body • Wetness of the clothing • Air movement • Layers of clothing • Size of the individual
  8. 8. AUTOPSY 1. Weight, height, and physical characteristics are documented 2. Body is photographed, x-rayed, and examined with alternate light source (black light) for stains 3. Distinguishing characteristics – tattoos, scars, birthmarks 4. Clips fingernails and toenails for further analysis 5. If a rape case, swabs are taken of oral, anal, and vaginal cavities 6. Fingerprints and palm prints 7. Y-incision from shoulders down to abdomen 8. Saw collarbone and ribs 9. Internal organs are all removed, weighed, and measured 10. Blood and tissue samples are taken from each organ 11. If necessary, the scalp is peeled back, skull is opened and brain is examined
  9. 9. EVIDENCE TO BE COLLECTED AT AUTOPSY Autopsy: medical dissection and examination of a body in order to determine the cause of death • Victim’s clothing • Fingernail scrapings • Head and pubic hairs • Blood (for DNA typing) • Vaginal, anal, and oral swaps (sex-crimes) • Recovered bullets / knives from body • Hand swabs from shooting victims (for GSR analysis) • Viscera • Stomach Contents
  10. 10. BODY FLUIDS • Blood, semen, saliva, sweat, and urine can be analyzed to give investigators information about the crime as well as its victim or the suspect. • Chemicals and ultra violet light can be used at a crime scene to find body fluid evidence. Areas with potential evidence are swabbed, bagged and collected in vials, which are air tight and have a low risk of cross contamination. Examples: • Vomit and urine can be used to test for alcohol, drugs, and poisons. • Cigarette butts may contain dried saliva. • Semen containing sperm is valuable for DNA analysis. • Blood can provide DNA evidence and blood spatter can provide clues about the crime.
  11. 11. FORENSIC ANTHROPOLOGY • Recovery, Identification and examination of human skeletal remains and estimate the time of death. – Trying to determine origin, sex, approximate age, race and skeletal injury – May create facial reconstruction – Identify victims of mass disaster such as plane crash – Mass Murder (Oklahoma bombing, plane crashes, World Trade) – Earlier man (Mummies, Iceman, Lindow man) – Prehistoric Animals (Dinosaurs) – Bones Tells us many thing: • Age • Ethnicity • Gender • Height • Weight • Build • Pathologies like old injuries
  12. 12. WHAT DO FORENSIC ANTHROPOLOGISTS DO? Generally, forensic anthropologists DO NOT do any of the following: • Collect trace evidence (hair, fibers) • Run DNA tests • Analyze ballistics or weapon evidence • Analyze blood spatter • Conduct autopsies What a forensic anthropologist does DO to aid in a case: • Goes to a crime scene to assist in the collection of human remains • Cleans up the bones so that they may be looked at • Analyzes skeletal remains to establish the profile of the individual • Looks at trauma evident on the bones to establish the pathway of a bullet or the number of stab wounds • Works with a forensic odontologist (dentist) to match dental records • Testifies in court about the identity of the individual and/or the injuries that might be evident in the skeleton
  13. 13. AGE DETERMINATION Most accurate estimations 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.
  14. 14. RACE AND RACE CHARACTERISTICS 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:  Caucasoids—have a long, narrow nasal aperture, a triangular palate, oval orbits, narrow zygomatic arches and narrow mandibles. European, Middle Eastern, and Indian descent .  Negroids—have a wide nasal aperture, a rectangular palate, square orbits, and more pronounced zygomatic arches. The long bones are longer, have less curvature and greater density. Negroid—African, Aborigine, and Melanesian descent  Mongoloids—have a more rounded nasal aperture, a parabolic palate, rounded orbits, wide zygomatic arches and more pointed mandibles. Mongoloid— Asian, Native American and Polynesian descent
  15. 15. ESTIMATION OF HEIGHT The height of a person can be calculated by using the length of certain long bones, including the femur, tibia, humerus, and radius. Below are the equations to determine average measurements for both male and female. (All measurements are in centimeters) Male Female femur x 2.23 + 69.08 femur x 2.21 +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 + 73.50
  16. 16. FORENSIC ODONTOLOGY • Provide information about the identification of victims when the body is left in an unrecognizable state because they are unique to an individual • Teeth are composed of enamel which is the hardest substance in the body • The identity of an individual can be determined by comparing a person’s teeth to their 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. • Characteristics of teeth, alignment, and overall structure of the mouth provide method for identification • Also analyze bite marks • X-rays are good record of teeth
  17. 17. FACIAL RESTORATION After determining the sex, age, and race of an individual, facial features can be built upon a skull to assist in identification. • The photo imposition technique involves imposing a photo of the skull over a photo of the face in question. • Three dimensional reconstruction technique involves adding depth markers for tissue thickness onto a skull. Erasers are used to make tissue depths at various points on the skull. • Clay is placed over the skull, to match the depth of the markers, to simulate skin and muscle. The features are then smoothed out to make a 'face.' • This has worked in a number of missing persons cases, but is considered more art than science.
  18. 18. 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
  19. 19. FORENSIC ENTOMOLOGY • Study of insects and their relation to a criminal investigation. Flies, beetles, and other insects can provide useful clues about a corpse. • After decomposition begins, insects such as blow flies are the first to infest the body • Forensic entomologists use factors such as weather conditions, the location and condition of the body, and their knowledge of the life cycles of insects to help them estimate the postmortem interval or PMI (the time between death and the discovery of the body).
  20. 20. FORENSIC PSYCHIATRY • Specialized area in which the relationship between human behavior and legal proceedings is examined – Civil cases: determine whether people are competent to make decisions about wills, refusing medical treatment, etc. – Criminal cases: determine whether people are competent to stand trial – Develop suspect’s behavior profile • Forensic Psychiatry serves to define what mental illness and disorder are, what creates mental illness and disorder, how they are diagnosed and how they are treated. In cases of mental illness, the individual does not function well in reality because of emotional fluctuations or distorted point of view interpretation. • Mental disorder is a clinically significant behavior or psychological syndrome or pattern that is associated with present distress or disability or with a significantly increased risk of suffering death, pain or disability or important loss of freedom.
  21. 21. FORENSIC PROFILING • Profiling is a label given to the process by which a trained forensic psychologist sifts through the aspects of a crime scene to develop a description of the personality of the perpetrator. • This personality description can include age, sex, occupation, behavioral disorders, upbringing, marital status, they type of place the perpetuators would live in and its general condition, the type of person the perpetuators might live with, what type of car he drives, if he has a speech impediment or acne or some other type of disability or difficulty in relating to others. • They will tell you how the crime was committed. • Profiling does not produce a name. What it does produce is a detailed personality profile of a perpetrator that investigators can use to focus an investigation and pare down the list of suspects. It can also provide them with strategies on how to approach the subject during interrogation and how to break him down on the witness stand at trial.
  22. 22. FORENSIC ENGINEERING Forensic engineering is the investigation of materials, products, structures or components that fail or do not operate or function as intended, causing personal injury or damage to property. The consequences of failure are dealt with by the law of product liability. The field also deals with retracing processes and procedures leading to accidents in operation of vehicles or machinery. Generally the purpose of a Forensic engineering investigation is to locate cause or causes of failure with a view to improve performance or life of a component, or to assist a court in determining the facts of an accident. It can also involve investigation of intellectual property claims, especially patents. • Concerned with: – Failure analysis – Accident reconstruction – Cause and origin of fires or explosions • Answer questions such as how did an accident occur or what structural failure occurred
  23. 23. CASES THAT DEAL WITH FORENSIC ENGINEERING • Fires – Electrical – Gas/Propane Explosions • Accidents – Mechanical – Corrosion related • Electrocution • Carbon Monoxide Investigations Root cause failure analysis of mechanical equipments or parts. Performing stress analysis, finite element analysis, fracture mechanics, corrosion and fatigue analysis on the failed or deformed components. Using classical methods or state of art finite element analysis.
  25. 25. FAILURE ANALYSIS Building Materials • Concrete, mortar and plaster failures. • Ceramic failures, including cracked, lifting, worn and slippery tiles, and damaged glass. • Adhesives and sealants for masonry, tiles and other surface finishes on buildings and pools. • Corrosion of pipes and structural steel • Paint system problems, thickness, peeling and durability. Motor Vehicles • Evaluation of substitute components • Mechanical failure analysis of all components, including suspension, engine components, transmission and braking systems • Tyre failure, including determination of the cause of blow-outs • Mechanical failure of components in the suspension, engine, braking, safety restraint systems, and tyre failures on passenger and sports cars, trucks and mining equipment Engineering Failures • Structural and component failures in cranes, machines and aircraft including determination of mechanism and cause • Non-destructive testing failures • Assessment of corrosion mechanisms Public Liability • Mechanical Failure of products and equipment such as ladders, chairs, racking systems, motorised scooters and trolley systems • Incident investigations involving machines and equipment, determination of contributing factors, including compliance with Occupational Health and Safety and other standards
  26. 26. TESTING METHODS • Accelerated Life Testing – This is a method of testing the life span of a product, conducted in an environment to stimulate the product’s behaviour in specific conditions with the results occurring at an accelerated rate. • Nuclear Magnetic Resonance Spectroscopy – NMR spectroscopy is a technique that can be employed in the detection of minute traces of impurities in a material. • Optical Microscopy – Simple microscopy or a hand magnifier may be used for close examination of the surface of a product. This method can show cracks, scratches, contamination, and any other defects on the surface of the material. • Radiography – Using X-rays or neutrons, it is possible to internally examine products for any defects within the material. • Scanning Electron Microscopy – A form of microscopy used to detect minute damages caused to structures or items, it may also be possible to reveal the presence of harmful or corrosive chemicals on the object.
  27. 27. FRACTURE MATCHES • When an object broken, torn, or cut, two unique edges are formed, which are referred to as fracture lines. • These edges can be compared by the naked eye or with microscopes to see if they fit together , which indicates that they may have been part of the same object at one time. • Investigators may compare the edges on pieces of tape, glass fragments, paint chips, pieces of a car from an accident, paper bag, etc. to find possible matches.
  28. 28. FORENSIC PHOTOGRAPHY Method Number photo in corresponding photo log book OVERVIEWS: from farthest part of scene (outward working inward) MEDIUMS: closer views UP-CLOSE: close up of items/scene, 2 of every picture, 1 with/1 without scale Use High Contrast, Zoom, Wide Angle and B/W photographic methods PHOTOS of Body are taken from all five angles: From above, From feet, From left side, From right side, and From head
  29. 29. FORENSIC PHOTOGRAPHY • Luminol Photography • Microscope and Comparative Scope Photography • Identification Photography • Fingerprint Photography • Infrared (IR) Photography • Ultraviolet (UV) Photography • Footwear Impression Photography • Impression Photography • Electrostatic Dust Print Photography • Photographing Trajectories • With Laser Beams
  31. 31. COMPUTER FORENSICS • What is Computer Forensics?? – Computer forensics involves the preservation, identification, extraction, documentation, and interpretation of computer media for evidentiary and/or root cause analysis. – Evidence might be required for a wide range of computer crimes and misuses – Multiple methods of • Discovering data on computer system • Recovering deleted, encrypted, or damaged file information • Monitoring live activity • Detecting violations of corporate policy – Information collected assists in arrests, prosecution, termination of employment, and preventing future illegal activity
  32. 32. COMPUTER FORENSICS • What Constitutes Digital Evidence? – Any information being subject to human intervention or not, that can be extracted from a computer. – Must be in human-readable format or capable of being interpreted by a person with expertise in the subject. • Computer Forensics Examples – Recovering thousands of deleted emails – Performing investigation post employment termination – Recovering evidence post formatting hard drive – Performing investigation after multiple users had taken over the system
  33. 33. COMPUTER FORENSICS Non Business Environment • Theft of trade secrets • Fraud • Extortion • Industrial espionage • Position of pornography • SPAM investigations • Virus/Trojan distribution • Homicide investigations • Intellectual property breaches • Unauthorized use of personal information • Forgery • Perjury Business Environment • Theft of or destruction of intellectual property • Unauthorized activity • Tracking internet browsing habits • Reconstructing Events • Inferring intentions • Selling company bandwidth • Wrongful dismissal claims • Sexual harassment • Software Piracy
  34. 34. COMPUTER FORENSICS: STEPS – Acquisition • Physically or remotely obtaining possession of the computer, all network mappings from the system, and external physical storage devices – Identification • This step involves identifying what data could be recovered and electronically retrieving it by running various Computer Forensic tools and software suites – Evaluation • Evaluating the information/data recovered to determine if and how it could be used again the suspect for employment termination or prosecution in court – Presentation • This step involves the presentation of evidence discovered in a manner which is understood by lawyers, non-technically staff/management, and suitable as evidence as determined by United States and internal laws
  37. 37. SOIL • Soil possesses many physical and chemical properties that can be exploited in comparison of known and unknown samples. • Soil is produced by a complicated process that is influenced by factors such as temperature, rainfall, and the chemicals and minerals present in the material from which it forms. Because of all the factors that affect soil formation, soil from different locations can have different physical and chemical characteristics that are useful to forensic scientists. • The uniqueness of soil composition has helped locate burial sites and link suspects to crime scenes, identify thief's. • Soil is part of the top layer of Earth’s crust, where most plants grow. Soil contains minerals, decaying organisms, water, and air, all in varying amounts. Soil texture describes the size of the mineral particles that make up soil. There are three main soil grain sizes: sand, silt, and clay. • Sand is formed by the action of wind and water on rocks, called weathering. As wind and water move rocks around, the rocks collide with other rocks. These collisions break the rock into smaller and smaller pieces until small grains, called sand, remain.
  38. 38. SOIL EXAMINATION • Layers of soil or mud taken from shoes or the wheels of vehicles can show that a suspect was present at a series of locations. • Scientists compare the size, shape, and color of soil by looking at samples macroscopically for soil type, amount of plant and animal material, and particle size. • A systematic approach for forensic soil examination is outlined, which combines soil morphology (e.g., color, consistency, texture, and structure), mineralogy (powder X-ray diffraction), chemistry (e.g., based upon infrared spectroscopy analyses), biology, and spatial field mapping information. • Soil can also be identified and compared by studies using density columns, moisture content, and chemical testing for mineral content. • Before using X-ray diffraction, a soil sample is crushed into a very fine powder. The powder is then tested, and as the X-ray is deflected, it produces a pattern on a film. Each mineral and chemical produces a specific pattern. The pattern produced by the sample allows scientists to determine the mineral composition of the soil.