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Download Forensic Pathology - Ms. Collins forensic science
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WARM-UP During a recent police investigation, Chief Inspector Stone was interviewing five local villains to try and identify who stole Mrs Archer's cake from the mid-summer fair. Below is a summary of their statements: Arnold: it wasn't Edward it was Brian Brian: it wasn't Charlie it wasn't Edward Charlie: it was Edward it wasn't Arnold Derek: it was Charlie it was Brian Edward: it was Derek it wasn't Arnold It was well known that each suspect told exactly one lie. Can you determine who stole the cake? 1 FORENSIC TAPHONOMY FORENSIC TAPHONOMY Forensic taphonomy is the study of the history of the body since death. Taphonomy is derived from Greek taphos (burial) and nomos (laws). Taphonomy is important because it may assist in; Estimating the time since death by observing postmortem changes Identification of the individual Ability to determine cause and manner of death CATEGORIES OF TRAUMA 1. 2. 3. 4. Mechanical – sharp or blunt Thermal – hyperthermia or hypothermia Chemical – drgus or poisins, CO kills by asphxyation Electrical – causes ventricular fibrilation Asphyxial – low Oxygen Eccymosis Ligature Marks Petechia 5 MECHANICAL Sharp Knives, Swords, Axes Blunt Firearms Handgun Shotgun Nonfirearms 6 Blunt force Hesitation 7 Double edge Slash wound Single edge 8 ENTRANCE WOUNDS Close Contact wound – skin blackens Red discoloration due to released CO (few inches) Larger lacerations on head wounds Intermediate Less gas effects Stippling/tattooing from unburned powder Distance Circular defect Abraded rim on skin 9 Shotgun Close Contact Wound Intermediate Close Handgun 10 Distance wound Intermediate – Stippling/tattooing 11 EXIT WOUNDS Not always larger Small slit shaped Slow speed - few side lacerations High speed – many side lacerations “bunny ears” Shored exit – due to clothes, easily confused with distance entrance but abrasions are wider than entrance 12 With lacerations Shored exit versus entrance wound Without laceratio ns 13 TRAUMA TERMS TO KNOW Hematoma – “goose eggs”, tumor of blood Contusion – leaves patten of weapon when blood leaks out of cells Laceration – blunt force wound Incised wound – sharp force wound Stab – longer length than width wound Exsanguination- bleed out Perforating – gun wound with entrance and exit Penetrating – gun wound with no exit 14 WHAT IS FORENSIC TAPHONOMY Taphonomy is the study of the processes that affect the decomposition, dispersal, erosion, burial, and re-exposure of organisms after, at, and even before death. Forensic Taphonomy is a subfield of forensic anthropology. BIOTAPHONOMY Biotaphonomy examines the remains themselves and asks how decomposition and destruction of the hard and soft tissue was brought about. Biotaphonomic variables can be subdivided Environmental factors Individual factors Cultural factors GEOTAPHONOMY Geotaphonomy is the study of how someone who buries a body, and how the body itself affects the surrounding geological and botanical environment. CONTRIBUTIONS OF METHODS AND THEORY Forensic taphonomy requires interdisciplinary input from biologists, archeologists, anthropologists, entomologists, botanists and geologists, among others. Forensic anthropologists are primary facilitators of taphonomy into forensics CONTRIBUTIONS OF METHODS AND THEORY Archaeological techniques of recognition, search, recovery, and documentation of findings are critical in taphonomy Other techniques, such as 3-D mapping, stratigraphy, botanical and entomological collection, conservation, and exhumation are used. TAPHONOMIC FACTORS Forensic Taphonomic history includes: Actual death Interval of bone exposure through soft tissue modification Potential interval of bone modification Point of discovery and collection TAPHONOMIC FACTORS Of particular interest in medicolegal death investigation is: Perimortem interval, Boundary between soft tissue modification and bone exposure, Interval in which bone is exposed to modifying agents (weather, water, soil, animals, etc) TAPHONOMIC FACTORS Perimortem interval- discriminating antimortem from postmortem injuries to bone is difficult Antimortem/Perimortem injuries include ability to define moisture and grease content of bone, i.e.; greenstick, or spiral fractures Postmortem fractures include clean brittle breaks, parallel or cross fracture of long axis of bones Moisture loss occurs over time TAPHONOMIC FACTORS Several factors affect estimates of postmortem interval: Determining triggering event Cultural factors Environmental factors Carcass temperature and loss of blood Atmospheric conditions Location of deposition of body – water, underground, on top of ground TAPHONOMIC FACTORS Animals and human remains Most commonly found scavengers of human remains are: Carnivores Rodents Insects Microbes TAPHONOMIC FACTORS Dogs and rodents are primary scavengers of remains Dogs and cats leave v-shaped defects in soft tissue Clawing, digging or tugging at remains can also alter appearance Rodents leave tightly circumscribed and even margins, dual teeth marks Scavengers and feces also leave behind hair, tracks TAPHONOMIC FACTORS Plants and human remains: Seasonal shedding of leaves or needles can cover remains Roots can cause mechanical damage Fungi can secrete acid Microenvironmental changes can be caused by rootlet proximity to bones and subsequent moisture conservation and microbial activity HUMAN REMAINS IN WATER ENVIRONMENTS Water presents a myriad of problems with death investigations: Type of water body (ocean, river, lake) Disarticulation in water and problems with original location of water Temperature, depth, and current of water all affect body decomposition, as does seasonal weather BURIED REMAINS Major problem by burial is locating grave Methods to determine grave location include: Witness statements Visual clues Cadaver dogs Trenching and probing Area photography Remote sensing BURIED REMAINS Buried bodies normally decompose slower than bodies on surface due to: Less exposure to scavengers and insects Temperature fluctuates less the deeper the body is in grave Less exposure to weather Compaction of soil Differences in pH due to decaying matter Moisture level The Body Farm The research farm, known as The Body Farm, was established in 1981 by Bill Bass, a professor of forensic anthropology. http://video.nationalgeographic.com/ video/player/science/health-humanbody-sci/human-body/body-farmsci.html THE BODY FARM PRIMARY GOAL: To understand the processes & timetable of postmortem decay, primarily to improve determining the "time since death” The Body Farm is a simulation of various crime scenes using real human bodies. Started in 1970-80’s to study Forensic Anthropology (the study of human decomposition after death). THE BODY FARM Used by Law Enforcement, Medical Examiners, Entomologists, Cadaver Dogs, Anthropologists & FBI for Crime Scene Training. The BF uses unclaimed cadavers & volunteers (who donate their body to science after death) Only 2 Facilities in the U.S. Univ. of Tennessee (original) Western Carolina University Texas State University Sam Houston State University TYPES OF RESEARCH How does the decomp rate compare in: sunshine vs shade? In cool weather vs hot weather? In a shallow grave vs on the ground? In water? Inside a car? What effect do other variables have—humidity, insect activity, clothing, body weight, and so on? WHY IS TSD SO IMPORTANT? 1st question at most murder scenes: "How long has this person been dead?“ It's crucial to know when the crime was committed. it can help narrow the search for a suspect or it can help rule out potential suspects who had alibis at the time the victim was killed.
