Forensic chemistry introduction
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Forensic chemistry introduction






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Forensic chemistry introduction Forensic chemistry introduction Presentation Transcript

  • Do Now Withyour partner list as many types of forensic evidence as you can  Think of all those CSI’s and L&O’s you’ve watched!  Team with longest list gets bonus points!
  • Forensic Science An Introduction
  • What is forensic science? Science in service to the law  “…the application of science to those criminal and civil laws that are enforced by police agencies in the criminal justice system.” Saferstein
  • What’s the key concept in FS? Locard’s Exchange Principle (~1910)  Whenever a criminal comes in contact with a person or object there is a cross-transfer of evidence.
  • What are the consequences ofLocard’s Exchange Principle?  The perpetrator leaves evidence behind and also takes evidence away  The longer you wait before collecting evidence the less there is left  Every person at the crime scene including police investigators will contaminate it
  • Realistic?
  • What is Forensic Science Trying to Do? The goal of Forensic Chemistry is to determine the provenance of a sample.  Link it to a person, place or thingprov·e·nance Pronunciation: präv-n&n(t)s, prä-v&-"nän(t)s Function: noun Etymology: French, from provenir to come forth, originate, from Latin provenire, from pro- forth + venire to come -- more at PRO-, COME 1 : ORIGIN, SOURCE 2 : the history of ownership of a valued object or work of art or literature
  • The Crime Lab Physical Science Firearms Biology Photography DocumentsPathologist Crime Odontologist Lab Voiceprint Polygraph Analysis Latent Toxicology Evidence Engineer Fingerprints Psychiatrist Collection Anthropologist Entomologist
  • Activity Time! Assign each of the items in your evidence list to the proper department in the crime lab Feel free to add more types of evidence Populate your crime lab with your favorite TV characters
  • Anthrax Letters 5 dead 17 sickenedWhat types of evidence would you look for?
  • Anthrax Letters Trace hair and fibers in envelope Ink analysis may reveal manufacturer DNA from stamp or envelope seal Cellophane tape ends match over four letters Paper examination may identify manufacturer Fingerprints Photocopier toner may reveal manufacturer Handwriting analysis shows four letters written by same person Indented writing Bar codes for mail handling
  • Analytic vs. Forensic Chemistry SimilaritiesAnalytic Forensic Wants to find  Wants to find composition of composition of samples samples  Compounds  Compounds  Proportions in  Proportions in mixtures mixtures Uses same  Uses same instruments as instruments as forensic analytical
  • Analytic vs. Forensic Chemistry DifferencesAnalytic Forensic Known source  Need to determine Good idea of what the source composition is likely  Little knowledge of to be composition Used for quality  Often complex control mixtures so hard to Well defined samples find appropriate and controls controls
  • Roles of the Forensic Scientist Analyze physical evidence Provide expert testimony Train evidence collection units in recognition, collection and preservation of evidenceWould you expect to see Gil Grissom collecting evidence at a crime scene?
  • The Expert Witness An expert witness can testify as to his/her opinion of what the evidence indicates A lay witness can only testify as to fact
  • The Expert Witness Trial judge must be satisfied that the expert  Has skill or knowledge that will aid the court in determining the truth  Education (degrees, courses)  Training (internship under experienced practitioner)  Experience (years on the job, publications, professional societies) Trial judge is the gatekeeper
  • The Expert Witness Jury assigns weight to the expert’s opinions Jury looks at  Credentials  Demeanor  Whether material is presented simply and clearly Jury is the trier of fact
  • And Now for Some Expert Testimony My Cousin Vinny
  • A Big Driver in the Plot Can the evidence be admitted into court?
  • Admissibility: A Moving Target Frye v. US (1923)  Scientific evidence is admissible only if it has gained general acceptance in the field  Rejected polygraph opinions Historical Perspective  Tennessee v. John Scopes (1925)  The Monkey Trial
  • Admissibility: A Moving Target Coppolino v. State of Florida (1968)  Doctor accused of poisoning his wife with succinylcholine chloride  New and unique tests performed specifically for this case  Detected by-products of metabolism of poison (succinic acid)  Admissible if based on scientifically valid principles and techniques
  • Admissibility: A Moving Target Federal Rule of Evidence 702 (1975)  Approved by Congress  More flexible general relevance test for admissibility of opinion testimony by experts  “If scientific, technical or other specialized knowledge will assist the trier of fact to understand the evidence or to determine a fact at 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.”
  • Admissibility: A Moving Target Daubert v. Merrell Dow Pharmaceuticals (1993)  When expert evidence based on “scientific knowledge” is offered at trial, the judge acts as gatekeeper to determine if the evidence is “reliable”  Four suggested factors in determining reliability  Testable using the scientific method  Peer reviewed  Error rates  Acceptability to the scientific community  Trial judge given lots of flexibility  Muddy waters—what is scientific knowledge?  What about other types of experts?
  • Admissibility: A Moving Target Why Daubert won on appeal  When Congress passed Rule 702 it ignored the Frye general acceptability criterion  Frye was no longer “good law”--
  • Admissibility: A Moving Target Kumho Tire Co v. Carmichael (1999)  Daubert factors are extended to non-scientist expert witnesses.  Daubert factors are not the only ones that can be considered  Trial judge now has enormous flexibility
  • And it’s not settled yet….. Daubert and Kumho apply to federal cases only 18 State Courts have adopted Daubert standards Other State Courts have rejected Daubert and still use a modified Frye standard
  • What’s driving the growth of FS? Miranda decision  Fewer confessions Increase in drug seizures and arrests  More testing DNA profiling  More testing with sophisticated equipment Other new technologies
  • Miranda vs. Arizona (1966) Before questioning by the police, suspects must be informed that they have:  The right to remain silent  The right to consult an attorney  If indigent an attorney will be provided for them  Anything they say may be used against them in court Arizona Department of Library Archives and Public Records)
  • Dickerson Dickerson vs US (2000)  Congress passed law in 1968 saying voluntary confessions are exempt from Miranda  Supreme Court overrules Congress in 2000  Congress can’t overrule the Supreme Court on constitutionally guaranteed rights except by the amendment process
  • Results of Miranda Confessions are less likely to hold up in court since the burden of proof of Miranda statement lies on police Police and prosecutors rely more independent (scientific) evidence to prove guilt
  • What is the most common task a forensic scientist performs? Take 5 minutes and discuss this in groups of 4 and then be ready to report out your reasoning.
  • Crime Wave or Better Enforcement?
  • Federal Drug Seizures
  • Arrests by Drug Type
  • The Economics of Drugs According to the United Nations Office on Drugs and Crime, "[T]he value of the global illicit drug market for the year 2003 was estimated at US$13 bn [billion] at the production level, at $94 bn at the wholesale level (taking seizures into account), and at US$322bn based on retail prices and taking seizures and other losses into account." This is larger than the total economies of 88% of the countries in the world! Source: United Nations Office on Drugs and Crime (UNODC), World Drug Report 2005 (Vienna, Austria: UNODC, June 2005), p. 127.
  • Average % THC in Marijuana SeizuresRecent seizures in Atlanta had plants with 18% THC content.
  • The Forensic All Stars Mathieu Orfila (1787-1853)  Father of toxicology Alphonse Bertillon (1853-1914)  First system of personal identification Francis Galton (1822-1911)  Classification of fingerprints Dr. Leon Lattes (1887-1954)  Determination of blood groupings from dried blood stains
  • The Forensic All Stars Calvin Goddard (1891-1955)  Father of ballistics  Use of comparison microscope Albert S. Osborn (1858-1946)  Fundamental principles of document examination Walter C. McCrone (1916-2002)  Application of microscopy to analytic problems
  • The Forensic All Stars Hans Gross (1847-1915)  First text detailing application of science to criminal investigation Edmond Locard (1877-1966)  Locard’s Exchange Principle  Thereis an exchange of materials whenever two objects come in contact
  • What is Science? An organized body of knowledge about nature A method for exploring nature and the order in it A set of tools for solving problems about nature
  • Coast Guard Drug Seizures