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FORENSIC SCIENCE Introduction and Crime Scene Investigation Forensic Science •The word forensic is derived from the Latin forensis, meaning forum, a public place where, in Roman times, senators and others debated and held judicial proceedings. •Forensic Science is the study and application of science to matters of the law. (The term criminalistics is often used interchangeably with forensics.) 2 Forensic Science Forensic scientists use crime labs to help them examine evidence. Most crime labs will include several departments: physical science (including chemistry, physics, and geology) biology ballistics document examination photography toxicology and drug analysis fingerprints Besides using the departments listed above, forensic crime labs may also consult specialists in the following fields: anthropology computer technology voiceprint analysis psychiatry pathology taphonomy odontology entomology etc… engineering polygraphy 3 What is the role of forensics? • It is important to realize that the forensic scientist must pull from a wide array of knowledge and specialists to competently do his or her job. • Forensics is more of a team effort than one would imagine. (Forget CSI folks…….the real world is nothing like that.) • A death that is unexpected or is thought to have been caused by an injury or poison is always investigated for the purpose of determining whether or not it was a homicide. 4 Methodology The forensic scientist must be methodical in his or her work. He or she must first observe general characteristics of the evidence then observe more specific features. He or she must link evidence to a crime and to the suspects by identifying and comparing relevant material. All forensic scientists use the scientific method to conduct their investigations. 5 Criminal Justice and the Law There are a number of different kinds of law in the U.S. criminal justice system: 1. The U.S. Constitution – the supreme body of laws that governs our country. It overrules the constitutions of the individual states. 2. Statutory law – this is also called written or codified law and is the law on the books as enacted by a governmental body or agency having the power to make laws (such as congress). Statutory law is based on the constitution. 6 Criminal Justice and The Law 3. 4. Common Law or Case Law – these are laws made by judges. Precedents are set in appellate courts. The principle of recognizing previous decisions as precedents is called stare decisis, meaning “ to stand by the decision.” This makes for predictability and consistency in how laws are applied. Civil Law - Sometimes referred to as private law which deals with relationships between individuals involving such matters as property or contracts. It provides a formal means for conducting non-criminal business between individuals, businesses or agencies of government and other organizations. Civil cases are more interested in assigning blame than discovering intent. Civil cases usually involve a preponderance of evidence to convict. Violations of civil law are usually in the form of fines or transfer of prosperities. 7 Criminal Justice and the Law 5. Criminal Law – sometimes referred to as public law and deals with the regulation and enforcement of rights. Typically deals with offenses against an individual that are deemed offensive to society; the state becomes the plaintiff. In criminal cases, the prosecution must prove guilt. • • • A misdemeanor is a minor crime such as theft. A felony is a major crime such as murder or rape. Prosecution must prove guilt beyond a shadow of a doubt in order to convict. 8 Criminal Justice and the Law 6. Equity law - is remedial or preventative law. This may include things like injunctions or restraining orders. This will also include orders of protective custody. 7. Administrative law – includes rules or laws established by agencies such as the IRS, Social Security Administration, or branches of the military. 9 Bill of Rights 1. Innocent until proven guilty 2. Not to be searched unreasonably 3. Not to be arrested w/out probable cause 4. Against unreasonable seizure of personal property 5. Against self incrimination 6. Right to fair questioning 7. Right to protection from physical harm throughout the justice process 8. Right to an attorney 9. Right to trial by jury 10. Right to know any charges against oneself. 11. 12. 13. 14. 15. 16. 17. 18. Right to cross examination. Right to speak and present witnesses Right not to be tried of the same crime Right against cruel and unusual punishment Right to due process Right to a speedy trial Right against excessive bail and fines Right to be treated the same as others regardless of race, gender, religious preferences, country of origin, and other personal attributes. 10 Steps in Pursuing Justice The steps are complex and confusing because of different jurisdictions (federal, state, local), different state rules and procedures, the type of crime committed, and a myriad of other factors influencing a case. Once a crime is committed, it must first be discovered, and a suspect may or may not be identified. Police investigate the crime and collect information and evidence. After an investigation ensues, and if there is enough evidence to establish probable cause, an arrest warrant is issued. 11 Steps in Pursuing Justice After arrest, the suspect is booked, and fingerprinted, photographed and informed of his/her Miranda rights. At this time the person is also informed of any charges being brought upon them. Within 72 hours of arrest, the suspect is brought before a magistrate, judge or commissioner for arraignment. An arraignment is a preliminary procedure in which the accused is informed of the charges and bail. The suspect also enters a plea at this point. 12 Steps in Pursuing Justice A person who pleads guilty is taken before a court for an evidentiary hearing; there is no jury. Some states require a grand jury for this step. The grand jury will decide on whether the accused will be indicted and then a trial date is set. Plea bargaining can occur at many points in the judicial process. About 90 percent of cases are plea bargained and settled without ever going to trial. 13 Federal Rules of Evidence The rules provide a platform for evidence to be presented in a trial. Evidence must be probative (must prove something) and not hearsay. Expert Witness: a person who is a specialist in a subject, often technical who may present his or her expert opinion without actually witnessing any occurrence relating to the case. This is an exception to the rule against giving an opinion in a trial, provided that the expert is qualified by his or her expertise, training, or special knowledge. 14 Federal Rules of Evidence The Frye standard – commonly called the general acceptance test. The Frye standard dictates that scientific evidence is admissible at trial only if the methodology or principle on which the opinion is based is sufficiently established to have gained general acceptance in the particular field to which it belongs. This applies to new or novel scientific methodologies. The Daubert Ruling- an updated revision of the Frye standard. Applies only in federal courts, but states are expected to use the decision as a guideline in setting standards. The trial judge must assume responsibility for admissibility and validity of evidence presented in his or her court. 15 CORPUS DELICTI • You must prove: “Body of the Crime” • that a crime has 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) 16 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 17 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. 18 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. • “Every contact leaves a trace.” 19 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 20 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 21 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 22 Eye Witness • Juries can be heavily influenced by eyewitness accounts. But how accurate are they? • Eyewitnesses can make perceptual errors for many reasons: • crime scene was too dark, encounter was too brief, or the presence of a weapon may have diverted their attention • the stress and fear involved in witnessing a crime may sharpen some people’s focus and confuse others • the time between the crime and questioning • new information – viewing mug shots or being asked leading questions 23 A TRUE EYEWITNESS Crazy 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.” 24 What is the value of Physical Evidence? • It can prove that a crime has been committed and set the scene for the investigation. • It can back up witness or prove it false. • It can link a suspect with a victim or with a crime scene. • It can determine the identity of people associated with a crime. • It can allow investigators to reconstruct a crime. 25 Evidence Characteristics Class - common to a group of objects or persons; a group of objects that share properties or characteristics (this evidence considered mainly circumstantial) Individual - can be identified with a particular person or single source. ABO Blood Typing Blood DNA Typing 26 Physical Evidence 1. 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 27 Physical Evidence 2. Pattern or Transfer Evidence produced by direct contact between a person and an object or between two objects. There are several ways of classifying evidence. In this class, we will use: • • • • Biological Chemical Physical Miscellaneous 28 Biological Evidence • • • • • • Blood Semen Saliva Sweat/Tears Hair Bone • • • • • • Tissues Urine Feces Animal Material Insects Bacterial/Fungal 29 Chemical Evidence • • • • • • • • Fibers Glass Soil Gunpowder Metal Mineral Narcotics Drugs • • • • • • • Paper Ink Cosmetics Paint Plastic Lubricants Fertilizer 30 Physical (impression) • • • • • Fingerprints Footprints Shoe prints Handwriting Firearms • • • • • Printing Number restoration Tire marks Tool marks Typewriting 31 Miscellaneous • Laundry marks • Voice analysis • Polygraph • • • • Photography Stress evaluation Psycholinguistic analysis Vehicle identification 32 Physical Evidence 3. 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 33 Physical Evidence 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. 34 Forensic Investigations • Include some or all of these seven major activities 1. Recognition - ability to distinguish important evidence from unrelated material • • • • Pattern recognition Physical property observation Information analysis Field-testing 2. Preservation - collection and proper preservation of evidence 35 Forensic Investigations 3. Identification - use of scientific testing • • • • • Physical properties Chemical properties Morphological (structural) properties Biological properties Immunological properties 4. 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. 36 Forensic Investigations 5. Individualization - demonstrating that the sample is unique, even among members of the same class. 6. Interpretation - gives meaning to all the information 7. Reconstruction - reconstructs the case events • • • • • Inductive and deductive logic Statistical data Pattern analysis Results of laboratory analysis Lee, Henry, Dr.. Famous Crimes. Southington: Strong Books, 2001. 37 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? 38