forensic science - mount mansfield union high school：法医科学-曼斯菲尔德山联合中学

FORENSIC SCIENCE,INTRODUCTIONCrime SceneInvestigation,2,Forensic Science,Definition: The application of scientific technology to supply accurate and objective information reflecting the events that occurred at a crime.What does a Forensic Scientist DO?Analyze physical evidenceProvide Expert TestimonyProvide training in the recognition, collection and preservation of physical evidence,Complex ReasoningIn Forensic Science,Deductive (reasoning from the general to the particular) andInductive Reasoning (reasoning from detailed facts to general principles)ClassifyingComparing and ContrastingProblem SolvingAnalyzing PerspectivesConstructing SupportError Analysis,4,The History of Forensic Science,Sherlock Holmes: a fictional character developed by Sir Arthur Conan Doyle; used a great deal of forensic detectionMathieu Orfila: toxicology (the detection of poisons)Alphonse Bertillon: anthropometry (personal identification through body measurements)Francis Galton: developed 1st fingerprint identification systemLeone Lattes: determined methods of using blood type as a means of identificationCalvin Goddard: firearms examinationAlbert Osborn: document examinationEdmund Locard: Developed the 1st police labJ. Edgar Hoover: director of the FBI: Organized the 1st FBI Crime Lab in 1932,5,Locards Exchange Principle,Whenever 2 objects come in contact with one another, they exchange some material (dust particles, hair, dead skin cells)Locard strongly believed that every criminal can be connected to a crime by dust particles carried from the scene,6,Branches of Forensic Science,Physical science: Using chemistry, physics, and geology to ID and compare crime scene evidenceBiology: blood, body fluids, hairs and fibers, entomologyPathology, psychology, odontology, any many more!,7,CORPUS DELICTI“Body of the Crime”,You must prove:that a crime occurredthat the person charged with the crime was responsible for the crimeTop Reasons for Committing a CrimeMoneyRevengeSexEmotion-love, hate, angerSource of EvidenceBodyPrimary and/or Secondary Crime SceneSuspect(s),8,4 Major FEDERAL Crime Labs:,FBIDrug Enforcement Administration (DEA)Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF)US Postal Inspection ServiceMost states also have their own, smaller crime labs,9,General Crime Lab Servicesand the materials each unit analyzes,Physical Science Unit: drugs, glass, paint, explosives, etcBiology Unit: blood and other bodily fluidsFirearms Unit: ballistics, comparisonsDocument Examination Unit: handwriting, typewriting, questioned documents (ransom notes, etc)Photography Unit: record all phyhsical evidence.Toxicology Unit: presence/absence of drugsLatent Fingerprint Unit: fingerprintsPathology Unit-,10,Forensic Pathology,Investigation of sudden unnatural, unexplained or violent deathsAnswer the questions:Who is the victim?What are the injuries, when did they occur, and how were they produced?5 manners of death: natural, homicide, suicide, accident, undetermined GO TO SLIDE 25.,11,Crime Scene Team,A group of professionals investigators, each trained in a variety of special disciplines.Team MembersFirst Police Officer on the sceneMedics (if necessary)Investigator(s)Medical Examiner (if necessary)Photographer and/or Field Evidence TechnicianLab ExpertspathologistserologistDNA experttoxicologistforensic odontologistforensic anthropologistforensic psychologistforensic entomologistfirearm examinerbomb and arson expertdocument and handwriting expertsfingerprint expert,12,INVESTIGATORS,“The wise forensic investigator will always remember that he must bring all of his life experiences and logic to find the truth. This means common sense, informed intuition, and the courage to see things as they are. Then he must speak honestly about what it adds up to.”Dr. Henry LeeChief Emeritus for Scientific Services and the former Commissioner of Public Safety for the state of Connecticut,13,First Officerat the Scene,AAssess the crime sceneDDetain the witnessAArrest the perpetratorPProtect the crime sceneTTake notes,14,Eye Witness,“Perception is reality.”As a result an eye witness may not be the best source of crime scene information.A police composite may be developed from the witness testimony by a computer program or forensic artist.,Faces Composite Programby InterQuest,15,Crime SceneSearch Patterns,Spiral,Grid,TWO of FOUR PATTERNS,16,Crime SceneSearch Patterns,Strip or Line,Quadrant or Zone,TWO of FOUR PATTERNS,17,Crime SceneSketch,Date: August 14, 2001Criminalist: Ann WilsonTime: 11:35Location: 4358 Rockledge DrSt. Louis, Mo.,A. Couch/sofaB. Female bodyC. KnifeD. Over turned LampE. ChairsF. TableG. Fireplace,c,D,E,E,E,E,E,A,G,F,18,Crime Scene Mapping(outdoors),Azimuth-uses a compass beam to determine the location of each piece of evidenceTriangulation-uses two points at the crime scene to map each piece of evidenceCoordinate or grid-divides the crime scene into squares for mapping.Suspended Polar Coordinate-for use in mapping evidence in a holeBaseline-set a north/south line and measures each piece of evidence from this line.,AZIMUTH,Determines:DirectionDistanceElevation,TRIANGULATION,Measure from A to B and then to the evidence in a triangular shape.,Coordinate or Grid Mapping,Set a north/south line from a datum point established by a GPS.,Make it a perfect square (4 x 4) by shooting the hypotenuse and setting in stakes every foot or meter.,Measure and map the location of each piece of evidence. Then collect evidence and place in containers by grid.,Baseline Mapping,Set a north/south line from the furthest most points of the crime scene. Then measure each piece of evidence from that baseline. Evidence will need a numerical measurement where the piece begins, ends and in the middle.,Evidence,Baseline,Suspended Polar Coordinate,Measure and map each layer of evidence as you move down the hole. Use the compass readings from the top to measure degrees and a tank dipping line to measure depth.,24,MAPPING TECHNOLOGY,The latest technology includes this Nikon Tsunami with computer. The exact location of all crime evidence can be determined and directly loaded into a computer to produce a crime scene map. Cost = $35,000 for the set.,25,Physical Evidence,Transient Evidence-temporary; easily changed or lost; usually observed by the first officer at the sceneOdor-putrefaction, perfume, gasoline, urine, burning, explosives, cigarette or cigar smokeTemperature-of room, car hood, coffee, water in a bathtub; cadaverImprints and indentations-footprints; teeth marks in perishable foods; tire marks on certain surfacesMarkings,26,Physical Evidence (cont),Pattern or Transfer Evidence-produced by direct contact between a person and an object or between two objects. There are several ways (at least 7) of classifying evidence. In this class, we will use:BiologicalChemicalPhysicalMiscellaneous,27,Biological Evidence,BloodSemenSalivaSweat/TearsHairBone,TissuesUrineFecesAnimal Material InsectsBacterial/Fungal,28,Chemical Evidence,FibersGlassSoilGunpowderMetalMineralNarcoticsDrugs,PaperInkCosmeticsPaintPlasticLubricantsFertilizer,29,Physical (impression),FingerprintsFootprintsShoe printsHandwritingFirearms,PrintingNumber restorationTire marksTool marksTypewriting,30,Miscellaneous,Laundry marksVoice analysisPolygraph,PhotographyStress evaluationPyscholinguistic analysisVehicle identification,31,Physical Evidence (cont),Conditional Evidence-produced by a specific event or action; important in crime scene reconstruction and in determining the set of circumstances within a particular event.Light-headlight; lighting conditionsSmoke-color, direction of travel, density, odorFire-color and direction of the flames, speed of spread, temperature and condition of fire,32,Conditional Evidence (cont.),Location-of injuries or wounds; of bloodstains; of the victims vehicle;of weapons or cartridge cases; of broken glass, etc.Vehicles-doors locked or unlocked, windows opened or closed; radio off or on (station); odometer mileageBody-position; types of wounds; rigor, livor and algor mortisScene-condition of furniture, doors and windows; any disturbance or signs of a struggle.,33,Evidence Characteristics,Class-common to a group of objects or personsIndividual-can be identified with a particular person or source.,ABO Blood Typing,Blood DNA Typing,34,Medical Examiner vs the Coroner,A medical examiner is a medical doctor, usually a pathologist and is appointed by the governing body of the area. There are 7 medical examiners in the state of Missouri and 400 forensic pathologists throughout the U.S.A coroner is an elected official who usually has no special medical training. In four states the coroner is a medical doctor.,35,Medical ExaminersResponsibilities,Identify the deceasedEstablish the time and date of deathDetermine a medical cause of death-the injury or disease that resulted in the person dyingDetermine the mechanism of death-the physiological reason that the person diedClassify the manner of deathNaturalAccidentalSuicideHomicideUndeterminedNotify the next of kin,36,THE BODYRigor Mortis,Temperature Stiffness Time Since of body of body Death,WarmWarmColdCold,Not stiffStiffStiffNot stiff,Not dead more than 3 hrsDead between 3 and 8 hrsDead 8 to 36 hoursDead more than 36 hours,37,THE BODYLivor Mortis,Livor mortis is the settling of the blood, causing the skin to change colors.Lividity indicates the position of the body after death. When lividity becomes fixed, then the distribution of the lividity pattern will not change even if the bodys position is altered. Lividity usually becomes fixed between 10 and 15 hours after death.,38,THE BODYAlgor Mortis,Algor mortis is body temperature. Average human body temperature: 98.6 F (37 C),39,Time Frame of Death,ConditionAppearancePeriphery blood drying30 min to 2 hrsBlue-green discoloration of skinRight and left area of abdomen24 hoursEntire abdomen36 hoursBloating36 to 48 hoursSkin slippage4 to7 daysAbsence of smell from bonesmore than 1 year,40,Time Frame of DeathEyeball Changes,ConditionAppearance Cornea drying (eyes open)minutesCornea drying (eyes closed)2 hoursCorneal cloudiness (eyes open)less than 2 hoursCorneal cloudiness (eyes closed) 12 to 24 hoursEyeball collapsemore than 24 hrs,41,One can die of a massive hemorrhage (the mechanism of death) due to a fall (cause of death) as a result of being pushed (homicide), jumping (suicide), falling (accident), or not being able to tell which (undetermined). All of which are manners of death.,THEREFORE,42,CRIME,+,=,What Happened?,Why Did ItHappened?,Who DidIt?,Crime Scene Evidence Collection Witness, Suspect and Motive Development,Post Scene Evidence Processing Cause, manner, time of death,Investigative Stage Profiling Means Motive Opportunity,Identificationand Arrest ofSuspect,43,Forensic Investigations,Include s