Criminalistics%20lecture%201-spg%2009%20rev-1 -...

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Unformatted text preview: Criminalistics Criminalistics : An Introduction to Forensic Science The Great Awakening The The application of DNA technology to criminal justice – Dr. Alec Jeffries The O.J. Simpson case – “If the glove don’t fit, then you must acquit” The Great Awakening The The media – Quincy, Law & Order, The New Detectives, CSI, etc. Barry Scheck and the reexamination of evidence The application of the principles of natural science to the criminal justice system Forensic Science Forensic Branches of Forensic Science Branches Jurisprudence Odontology Questioned Documents Psychiatry Engineering Pathology Toxicology Nursing Entomology Criminalistics Criminalistics Criminalistics The examination of physical evidence Areas of Criminalistics Areas Drugs Latent prints Firearms/tool marks Footwear/ Tire tread impressions Serology/DNA Trace evidence Digital evidence Bloodstain pattern analysis Fracture pattern matching Forensic Science Anthropology Psychiatry Jurisprudence Pathology Toxicology Odontology Engineering Questioned Documents Criminalistics Nursing Entomology Latent Prints Drugs FA/TM Serology DNA Trace Evidence FW/TT Digital Evidence Hairs/fibers Bloodstain Pattern Analysis Paint/polymers Soil Glass Fracture matching CSI or BSI? CSI Sherlock Holmes (Sir Arthur Conan Doyle) The premonition of things to come come Serology Fingerprinting Firearms identification Questioned Document exams Shakers & Movers of the Ages Shakers Mathieu Orfila (1787­1853) – Established field of forensic toxicology in Spain Alphonse Bertillon (1853­1914) – Anthropometry Calvin Goddard (1891­1955) – Developed comparison microscope And And Francis Galton (1822­1911) – Developed the first system of identification through fingerprints Dr. Leon Lattes(1887­1954) – Lattes crust method for typing dried stains More Shakers & Movers More Albert S. Osborn (1858­1946) – 1st significant text on QD Hans Gross (1847­1915) – Principles of criminal investigation Edmond Locard (1877­1966) – Scientific method (cross­transfer theory) Crime Laboratory Development Crime First lab in U.S. created by August Vollmer in LA (LAPD) in 1923 FBI lab organized in 1932 Forensic Science Research & Training Center established in 1981 Laboratory Jurisdictions Laboratory Federal – FBI, ATF, USPS, DEA, US Army, Navy & Air Force, Secret Service, US Customs State – Most populous states have lab or lab system County City Forensic Institutes Lab Services Physical science – chemistry, physics, geology Biology­ DNA Firearms Documents Photography Toxicology Latent Prints Polygraph Crime Scene Unit Deployment of Laboratories in the State of Texas the Federal labs – DEA (Dallas) State labs – Texas DPS (HQ + 13 field labs) County labs – Tarrant Co. M.E., Bexar Co. M.E., Harris Co. M.E., Jefferson Co. City labs – FW, Austin, Houston, Pasadena Institutes ­ SWIFS Lab Accreditation in Texas Lab Required by state law ASCLD­LAB ISO­17025 The Daubert Standard Standard Its Impact on Forensic Science Introduction Introduction Mid­1980s through 1990s: vocal protests to admissibility of highly questionable “expert testimony” Peter W. Huber (Center for Legal Research – The Manhattan Center): “the kind of expertise regularly accepted as admissible by courts was, frankly, ‘junk’ of scandalous lack of dependability” To address this, the Supreme Court decided Daubert v. Merrill­Dow Pharmaceuticals, Inc. in 1993 Set forth a new standard for admissibility of scientific evidence in U.S. federal courts Subsequently, Kumho Tire Co. V. Carmichael applied Daubert to all expert testimony in federal court Daubert has been adopted by many states There has been some concern regarding Daubert and forensic evidence Daubert Daubert Background on Admissibility of Scientific Evidence Scientific The Frye Standard of 1923: general acceptance in the relevant field Purpose of Frye: ‘to prevent…the introduction into evidence of specious and unfounded scientific principles or conclusions based upon such principles” Real focus was on “hired guns”: “The cowl does not make the monk” Frye Terms Open to Interpretation Terms Who comprises the relevant scientific community? What is general acceptance? The Biggest Drawback to Frye Frye Often results in excluding relevant, probative evidence OK audio tape case Federal Rules of Evidence Federal Frye was intentionally not incorporated due to its perceived problems Federal Rules of Evidence 702 offered a more liberal approach: “If scientific, technical, or other specialized knowledge will assist the trier of fact to understand the evidence or to determine a fact in issue, a witness qualified as an expert by knowledge, skill, experience, training or education, may testify thereto in the form of an opinion or otherwise.” Rule 703 requires the facts or data relied upon in the formulation of an expert opinion be of “a type reasonably relied upon by experts in the particular field in forming opinions or inferences upon the subject.” Adopted by 31 states by 1988 Role of Frye became unclear until 1993 when Daubert was adopted Applying Daubert Daubert Just because one is a medical doctor or a chemist does not make them an expert in all areas of medicine or chemistry The evaluation of credentials is up to the judge Once a judge decides that a person is qualified as an expert in a particular area, an examination of the methodology underlying the expert opinion is made to determine whether it utilizes valid scientific method and theories Evaluation Criteria Evaluation Its empirical testability Publication or peer review Acceptable known or potential rate of error General acceptance in the scientific community Failings of Daubert Daubert The criteria are neither exhaustive nor universally applicable Judge as gatekeeper The Expert Witness The Qualification – demonstrate ability in area (specialized training, experience) Competency – degrees, memberships, publications Appearance/demeanor Gives opinion testimony (as opposed to factual) Conclusions rendered – “ a reasonable scientific certainty” Analytical Principles Analytical Sensitivity – minimum amount of a substance required to give positive analytical results Specificity – ability to distinguish a substance to the exclusion of all other substances “Garbage in equals garbage Garbage out” out” Collection and preservation of physical evidence at the scene is critical CSI under lab supervision is the best policy, in lieu of criminalists themselves going to scene At the least, training should be provided by the lab to officers Lawyers vs. Scientists Lawyers Speculation vs. confirmation Innuendo vs. fact­based Absolute vs. no absolutes (terms lawyers use that forensic scientists do not) The Scientific Method The Identify the problem Make observations Develop an hypothesis Carry out tests Refine the hypothesis Develop a theory Applying the Scientific Method to Crime Scene Reconstruction Crime Each aspect of the physical evidence presents an opportunity for applying the scientific method For example: A fiber is found on a homicide victim’s body How is the scientific method going to be used? Define the problem: Is this fiber from the killer? Make observations: No similar fibers are observed in the immediate area of the body Develop an hypothesis: The fiber was left by the killer Applying the Scientific Method Applying Carry out tests: Collect control samples from the scene for laboratory comparison Refine the hypothesis: Take samples from the suspect’s clothing for laboratory comparison Develop a theory: Laboratory results indicate that similar fibers comprise the suspect’s jacket, therefore, the fibers at the scene either came from the suspect’s jacket or another source of fibers just like it The Theory of Crime Scene Reconstruction Reconstruction Deduction – once a theory has been proposed, the investigator has moved from inductive reasoning to deductive reasoning Testing/reevaluating – it is important to constantly reassess the theory to avoid the major pitfall of deductive reasoning: tunnel vision The goal of reconstruction: To develop a likely or probable sequence of events Why isn’t the goal to find out exactly what happened? Because it is improbable that an exact sequence of events can be ascertained Inconclusive is Good, Wrong is Bad Inconclusive If an exact sequence of events is proposed and one part is shown to be incorrect, the whole reconstruction is put to question Using modifiers such as “probable” and “likely” provides the reconstructionist with some leeway Definition: Class Characteristics Class General and/or measurable features of a specimen which indicate a restricted group source. They result from design factors, and are therefore determined prior to manufacture. Definition: Subclass Characteristics Subclass Features that may be produced during manufacture that are consistent among some items fabricated by the same tool. These are not determined prior to manufacture and are more restrictive than class characteristics. Definition: Individual Characteristics Individual Marks or features produced by the random imperfections or irregularities of tool surfaces. These characteristics can be used to individually associate a tool to a toolmark. Class, Subclass & Individual Class, Cause of Death Investigation Investigation Rule number 1: Never eat moving rice Time of Death Determination Determination Livor Mortis Rigor Mortis Algor Nortis Livor Mortis – Color of Death Livor Settling of blood after death Gravity causes blood to settle at lowest spot Apparent 20 minutes – 4 hours after death Not “fixed” (non­changing) for ~ 3 hrs (blanching upon finger pressure) 6­8 hrs will be fixed Variables to Consider Variables Bodies in water, etc. where no fixed position Situations w/o gravitational effect (spacecraft murder?) Decomposition Suntan/dark skin Anemia Massive loss of blood Visual Appearance Visual Usually dark red or purple Carbon monoxide poisoning, cyanide results in cherry red or pink appearance Likewise exposure to cold will affect Rigor Mortis – Stiffness of Death Death Chemical changes after death cause muscle tightening Starts in small muscles andmoves to larger Muscles of face and jaw usually go first 3 hrs. – no effect 4­6 – neck and jaw 6­8 – more advanced throughout body Rigor Mortis 12 hrs – full rigor 18­24 hrs – begins resolving, head and jaw are slack 30 hrs – rigor resolved, body limp Rigor Mortis Rigor Chemical changes involve accumulation and breakdown of adenosine triphosphate (ATP) ATP is the facilitator of muscle movement When ATP depleted, full rigor results Loss of rigor due to muscle fiber decomposition Rigor Variables Rigor Muscular individuals experience to higher degree Antemortem activity can deplete ATP and speed up onset Death in sleep can slow down due to more ATP at death Cadavaric Spasm – a Rarity Cadavaric Onset of rigor is instantaneous but diminishes in normal manner Brought on by sudden, violent impact such as instantly fatal gunshot wound or collision Happens but extremely rare Algor Mortis Algor Time of death determination based on body temperature Ambient temperature determined as well as body temperature Rate of cooling must be known Stomach contents and time of death determination death Typically digestion begins 15 minutes following ingestion Lots of variables Generally unreliable Not something a crime lab would be involved with ...
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