FORENSIC SCIENCE. INTRODUCTION Crime Scene Investigation

Transcription

1 FORENSIC SCIENCE INTRODUCTION Crime Scene Investigation

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??? 1. Analyze physical evidence 2. Provide Expert Testimony 3. Provide training in the recognition, collection and preservation of physical evidence 2

3 Complex Reasoning In Forensic Science Deductive (reasoning from the general to the particular) and Inductive Reasoning (reasoning from detailed facts to general principles) Classifying Comparing and Contrasting Problem Solving Analyzing Perspectives Constructing Support Error Analysis

4 The History of Forensic Science Sherlock Holmes: a fictional character developed by Sir Arthur Conan Doyle; used a great deal of forensic detection Mathieu Orfila: toxicology (the detection of poisons) Alphonse Bertillon: anthropometry (personal identification through body measurements) Francis Galton: developed 1 st fingerprint identification system Leone Lattes: determined methods of using blood type as a means of identification Calvin Goddard: firearms examination Albert Osborn: document examination Edmund Locard: Developed the 1 st police lab J. Edgar Hoover: director of the FBI: Organized the 1 st FBI Crime Lab in

5 Locard s 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 5

6 Branches of Forensic Science Physical science: Using chemistry, physics, and geology to ID and compare crime scene evidence Biology: blood, body fluids, hairs and fibers, entomology Pathology, psychology, odontology, any many more! 6

7 CORPUS DELICTI Body of the Crime You must prove: that a crime occurred that the person charged with the crime was responsible for the crime Top Reasons for Committing a Crime Money Revenge Sex Emotion--love, hate, anger Source of Evidence Body Primary and/or Secondary Crime Scene Suspect(s) 7

8 4 Major FEDERAL Crime Labs: FBI Drug Enforcement Administration (DEA) Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF) US Postal Inspection Service Most states also have their own, smaller crime labs 8

9 General Crime Lab Services and the materials each unit analyzes Physical Science Unit: drugs, glass, paint, explosives, etc Biology Unit: blood and other bodily fluids Firearms Unit: ballistics, comparisons Document Examination Unit: handwriting, typewriting, questioned documents (ransom notes, etc) Photography Unit: record all phyhsical evidence. Toxicology Unit: presence/absence of drugs Latent Fingerprint Unit: fingerprints Pathology Unit- 9

10 Forensic Pathology Investigation of sudden unnatural, unexplained or violent deaths Answer 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

11 Crime Scene Team A group of professionals investigators, each trained in a variety of special disciplines. Team Members First Police Officer on the scene Medics (if necessary) Investigator(s) Medical Examiner (if necessary) Photographer and/or Field Evidence Technician Lab Experts pathologist DNA expert forensic odontologist forensic psychologist firearm examiner document and handwriting experts serologist toxicologist forensic anthropologist forensic entomologist bomb and arson expert fingerprint expert 11

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 Lee Chief Emeritus for Scientific Services and the former Commissioner of Public Safety for the state of Connecticut 12

13 First Officer at the Scene A D A P T Assess the crime scene Detain the witness Arrest the perpetrator Protect the crime scene Take notes 13

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 Program by InterQuest 14

15 TWO of FOUR PATTERNS Crime Scene Search Patterns Spiral Grid 15

16 TWO of FOUR PATTERNS Crime Scene Search Patterns Strip or Line Quadrant or Zone 16

17 Crime Scene Sketch Date: August 14, 2001 Time: 11:35 Criminalist: Ann Wilson Location: 4358 Rockledge Dr St. Louis, Mo. A. Couch/sofa B. Female body C. Knife D. Over turned Lamp c A E D G E. Chairs F. Table G. Fireplace E F E E E 17

18 Crime Scene Mapping (outdoors) Azimuth--uses a compass beam to determine the location of each piece of evidence Triangulation--uses two points at the crime scene to map each piece of evidence Coordinate or grid--divides the crime scene into squares for mapping. Suspended Polar Coordinate--for use in mapping evidence in a hole Baseline--set a north/south line and measures each piece of evidence from this line. 18

19 AZIMUTH Determines: Direction Distance Elevation

20 Measure from A to B and then to the evidence in a triangular shape. TRIANGULATION

21 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.

22 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

23 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 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. MAPPING TECHNOLOGY 24

25 Physical Evidence Transient Evidence--temporary; easily changed or lost; usually observed by the first officer at the scene Odor--putrefaction, perfume, gasoline, urine, burning, explosives, cigarette or cigar smoke Temperature--of room, car hood, coffee, water in a bathtub; cadaver Imprints and indentations--footprints; teeth marks in perishable foods; tire marks on certain surfaces Markings 25

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: Biological Chemical Physical Miscellaneous 26

27 Biological Evidence Blood Semen Saliva Sweat/Tears Hair Bone Tissues Urine Feces Animal Material Insects Bacterial/Fungal 27

28 Chemical Evidence Fibers Glass Soil Gunpowder Metal Mineral Narcotics Drugs Paper Ink Cosmetics Paint Plastic Lubricants Fertilizer 28

29 Physical (impression) Fingerprints Footprints Shoe prints Handwriting Firearms Printing Number restoration Tire marks Tool marks Typewriting 29

30 Miscellaneous Laundry marks Voice analysis Polygraph Photography Stress evaluation Pyscholinguistic analysis Vehicle identification 30

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 conditions Smoke--color, direction of travel, density, odor Fire--color and direction of the flames, speed of spread, temperature and condition of fire 31

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 mileage Body--position; types of wounds; rigor, livor and algor mortis Scene--condition of furniture, doors and windows; any disturbance or signs of a struggle. 32

33 Cadaver Dogs Dogs with a sense of smell 100 times better than humans can sometimes find what would be overlooked. They are specially trained to locate injured, lost and/or deceased individuals. They are trained as air scent dogs or article (cloth) scent dogs. 33

34 Cadaver Dogs Dogs are trained to locate human body fluids including blood, hair, teeth, urine, and semen. The dog on the left in a training exercise is trying to locate clothing with blood. 34

35 Cadaver Dogs Looking at a crime scene, humans would probably miss something as small as this tooth. The dog found it within minutes of searching the scene.

36 Evidence Characteristics Class--common to a group of objects or persons Individual--can be identified with a particular person or source. ABO Blood Typing Blood DNA Typing 36

37 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. 37

38 Identify the deceased Establish the time and date of death Medical Examiner s Responsibilities Determine a medical cause of death--the injury or disease that resulted in the person dying Determine the mechanism of death--the physiological reason that the person died Classify the manner of death Natural Accidental Suicide Homicide Undetermined Notify the next of kin 38

39 The Autopsy Y incision from the left shoulder, down under the nipples and over to the right shoulder. Then place the scalpel in the pit of the abdomen, below the sternum and cut straight down and left of the belly button. Two Methods for Organ Removal--named for two German pathologists Rokitansky procedure:organs all come out at once. Virchow procedure: each organ is removed separately and immediately examined. A second incision of the body circumnavigates the skull from earto-ear behind the head. 39

40 The Corpse The way I see it, being dead is not terribly far off from being on a cruise ship. Most of your time is spent lying on your back. The brain has shut down. The flesh begins to soften. Nothing much new happens, and nothing is expected of you. --Mary Roach. Stiff. W. W. Norton & Company

41 THE BODY Rigor Mortis Temperature Stiffness Time Since of body of body Death Warm Warm Cold Cold Not stiff Stiff Stiff Not stiff Not dead more than 3 hrs Dead between 3 and 8 hrs Dead 8 to 36 hours Dead more than 36 hours 41

42 THE BODY Livor 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 body s position is altered. Lividity usually becomes fixed between 10 and 15 hours after death. 42

43 THE BODY Algor Mortis Algor mortis is body temperature. At a crime scene, it can be obtained in two different ways. Rectal temperature Liver temperature 43

44 Time Frame of Death Condition Periphery blood drying Blue-green discoloration of skin Right and left area of abdomen Entire abdomen Bloating Skin slippage Absence of smell from bones Appearance 30 min to 2 hrs 24 hours 36 hours 36 to 48 hours 4 to7 days more than 1 year 44

45 Condition Time Frame of Death Eyeball Changes Cornea drying (eyes open) Cornea drying (eyes closed) Corneal cloudiness (eyes open) Appearance minutes 2 hours less than 2 hours Corneal cloudiness (eyes closed) 12 to 24 hours Eyeball collapse more than 24 hrs 45

46 THEREFORE, One can die of a massive hemorrhage (the mechanism of death) due to a gun shot wound through the head (cause of death) as a result of being shot (homicide), shooting yourself (suicide), dropping a gun and it discharging (accident), or not being able to tell which (undetermined). All of which are manners of death. 46

47 CRIME What Happened? Crime Scene Evidence Collection Witness, Suspect and Motive Development Post Scene Evidence Processing Cause, manner, time of death Why Did It Happened? Investigative Stage + Profiling = Means Motive Opportunity Who Did It? Identification and Arrest of Suspect 47

48 Forensic Investigations Include some or all of these seven major activities Recognition--ability to distinguish important evidence from unrelated material Pattern recognition Physical property observation Information analysis Field-testing Preservation--collection and proper preservation of evidence 48

49 Investigations (cont) Identification--use of scientific testing Physical properties Chemical properties Morphological (structural) properties Biological properties Immunological properties Comparison--class characteristics are measured against those of know standards or controls; If all measurements are equal, then the two samples are considered to have come from the same source or origin. 49

50 Investigations (cont.) Individualization--demonstrating that the sample is unique, even among members of the same class. Interpretation--gives meaning to all the information Reconstruction--reconstructs the case events Inductive and deductive logic Statistical data Pattern analysis Results of laboratory analysis Lee, Dr. Henry. Famous Crimes. Southington:Strong Books,

51 Just A Thought It s not what you know that hurts you, its what you think you know and it s not so.....mark Twain How does this apply to forensic science and crime investigations? 51