510 likes | 520 Vues
FORENSIC SCIENCE. INTRODUCTION Crime Scene Investigation. 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
E N D
FORENSIC SCIENCE INTRODUCTION Crime Scene Investigation
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)
FACETS OF GUILT • Means--the ability of have committed the crime • Motive--the reason for committing the crime. (This doesn’t have to be proven or presented in a court of law, but its what everyone wants to know.) • Opportunity--time or availability to have committed the crime.
Murder Charges • 1st Degree Murder--premeditated • 2nd Degree Murder--killed intentionally, but not thought out as much ahead of time • Voluntary Manslaughter--usually involves sudden passion (fear, rage, anger, terror) • Involuntary Manslaughter (criminally negligent homicide)--killed someone, but unintentionally
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 serologist DNA expert toxicologist forensic odontologist forensic anthropologist forensic psychologist forensic entomologist firearm examiner bomb and arson expert document and handwriting experts fingerprint expert
Lead Investigator(for the staged crime scene) • Will escort the team of investigators to the crime scene • Will introduce the first officer • Will help lead the team through the questioning of the witness(s)
CRIME LAB HISTORY • First police crime lab in the world was established in France in 1910 by Edmond Locard • First police crime lab in the U.S. opened in 1924 • The Scientific Crime Detection Lab was founded in Evanston, Illinois in 1929 • The first FBI crime lab opened in 1932
Edmond Locard • French professor • Considered the father of criminalistics • Built the world’s first forensic laboratory in France in 1910 • Postulate--Locard Exchange Postulate Whenever two objects come into contact with each other, traces of each are exchanged.
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
First Officer at the Scene • A Assess the crime scene • D Detain the witness • A Arrest the perpetrator • P Protect the crime scene • T Take notes
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
A TRUE EYEWITNESSCrazy Criminal As a female shopper exited a New York convenience store, a man grabbed her purse and ran. The clerk called 911 immediately and the woman was able to give them a detailed description of the snatcher. Within minutes, the police had apprehended him. They put him in the car and drove back to the store. The thief was then taken out of the car and told to stand there for a positive ID. With that he replied, “Yes, Officer. . That’s her. That’s the lady I stole the purse from.”
Evidence Technician • Will set up numbers at the 10 pieces of evidence • One piece of evidence must come from each of the units in this semester. • Will help the other team collect evidence • Have the necessary equipment • Forceps • Bags--paper and plastic • Envelopes • Jars and Q-tips • Properly collect all evidence
Spiral Grid Crime Scene Search Patterns TWO of FOUR PATTERNS
Strip or Line Quadrant or Zone Crime Scene Search Patterns TWO of FOUR PATTERNS
Crime SceneSketch Date: August 14, 2001 Criminalist: Ann Wilson Time: 11:35 Location: 4358 Rockledge Dr St. Louis, Mo. • A. Couch/sofa • B. Female body • C. Knife • D. Over turned Lamp • E. Chairs • F. Table • G. Fireplace E c D G A E E E F E
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.
AZIMUTH • Determines: • Direction • Distance • Elevation
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. Measure and map the location of each piece of evidence. Then collect evidence and place in containers by grid. Make it a perfect square (4 x 4) by shooting the hypotenuse and setting in stakes every foot or meter.
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.
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.
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
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
Blood Semen Saliva Sweat/Tears Hair Bone Tissues Urine Feces Animal Material Insects Bacterial/Fungal Biological Evidence
Fibers Glass Soil Gunpowder Metal Mineral Narcotics Drugs Paper Ink Cosmetics Paint Plastic Lubricants Fertilizer Chemical Evidence
Fingerprints Footprints Shoe prints Handwriting Firearms Printing Number restoration Tire marks Tool marks Typewriting Physical (impression)
Laundry marks Voice analysis Polygraph Photography Stress evaluation Pyscholinguistic analysis Vehicle identification Miscellaneous
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
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.
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.
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. www.moregionck9search-rescue.com
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.
Evidence Characteristics ABO Blood Typing Blood DNA Typing Class--common to a group of objects or persons Individual--can be identified with a particular person or source.
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.
Medical Examiner’s Responsibilities • Identify the deceased • Establish the time and date of death • 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
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 ear-to-ear behind the head.
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. 2003
THE BODYRigor 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
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 body’s position is altered. Lividity usually becomes fixed between 10 and 15 hours after death.
THE BODYAlgor Mortis Algor mortis is body temperature. At a crime scene, it can be obtained in two different ways. • Rectal temperature • Liver temperature
Time Frame of Death • Condition Appearance • Periphery blood drying 30 min to 2 hrs • Blue-green discoloration of skin • Right and left area of abdomen 24 hours • Entire abdomen 36 hours • Bloating 36 to 48 hours • Skin slippage 4 to7 days • Absence of smell from bones more than 1 year
Time Frame of DeathEyeball Changes • Condition Appearance • Cornea drying (eyes open) minutes • Cornea drying (eyes closed) 2 hours • Corneal cloudiness (eyes open) less than 2 hours • Corneal cloudiness (eyes closed) 12 to 24 hours • Eyeball collapse more than 24 hrs
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.
CRIME Why Did It Happened? Who Did It? What Happened? Crime Scene Evidence Collection Witness, Suspect and Motive Development Investigative Stage Profiling Means Motive Opportunity Identification and Arrest of Suspect + = Post Scene Evidence Processing Cause, manner, time of death
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
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.
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, 2001
Remember: “HOW PLUS WHY EQUALS WHO” --John Douglas, former FBI profiler Keep this in mind as you set up your crime scene and work up your lab.