forensic science an introduction. what is forensic science? science applied to the law or in a legal...
TRANSCRIPT
Forensic Science
An Introduction
What is forensic science?
Science applied to the law or in a legal arena
“…the application of science to those criminal and civil laws that are enforced by police agencies in the criminal justice system.”
Saferstein
What is a 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 of Locard’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 thing
prov·e·nance Pronunciation: 'präv-n&n(t)s, 'prä-v&-"nän(t)sFunction: nounEtymology: French, from provenir to come forth, originate, from Latin provenire, from pro- forth + venire to come -- more at PRO-, COME1 : ORIGIN, SOURCE2 : the history of ownership of a valued object or work of art or literature
The Crime Lab
Psychiatrist
Odontologist
EntomologistAnthropologist
Pathologist
Engineer
Crime lab organization
Departments in the crime lab Biological evidence- examples? Trace evidence- examples? Document examination Photographs Computer technology evidence Ballistics and firearms Others?
Anthrax Letters
What types of evidence would you look for?
5 dead17 sickened
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 ChemistrySimilarities
Analytic Wants to find composition of samples
Compounds Proportions in mixtures
Uses same instruments as forensic
Forensic Wants to find composition of samples
Compounds Proportions in mixtures
Uses same instruments as analytical
Analytic vs. Forensic ChemistryDifferences
Analytic Known source Good idea of what the composition is
likely to be Used for quality control Well defined samples and controls
Forensic Need to determine source Little knowledge of composition Often complex mixtures so hard to
find appropriate controls
Roles of the Forensic Scientist
Analyze physical evidence Provide expert testimony Train evidence collection units in
recognition, collection and preservation of evidence
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
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
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 Seizures
http://www.usdoj.gov/ndic/pubs11/18862/images/fig1.gif
Recent 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. Karl Landsteiner(1868-1943)Determination of blood groupsNobel Prize
Alphonse Bertillon’s work in human stature
The Forensic All Stars
Calvin Goddard (1891-1955)Father of ballisticsUse of comparison microscope
Albert S. Osborn (1858-1946)Fundamental principles of document
examinationWalter 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
There is an exchange of materials whenever two objects come in contact
Who are the all-stars now?
Dr. Henry Lee Dr. Michael Baden Dr. Bill Bass Others?
The River Dell Doctor Dr. Jascelevich
Charged with 1st degree murder of patients.
Trial led to mistrial as evidence was lacking.
Curare muscle relaxer. Used on patients but also used for research on animals by Dr. J
Scientific tests for the presence of by product of curare insuffiencient.
Mistrial- charges dismissed Second trial 10 yrs. Later b/c tests for
by product of curare now sufficient. Exhumed bodies- only some
chemical found. Acquitted
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