Download Forensic Science

Forensic Science
SFS1. Students will recognize and classify various types of
evidence in relation to the definition and scope of Forensic
Science.
a. Compare and contrast the history of scientific forensic
techniques used in collecting and submitting evidence for
admissibility in court (e.g. Locard’s Exchange Principle,
Frye standard, Daubert ruling).
ESSENTIAL QUESTIONS
1. What is forensic science?
2. What is evidence and how is it used by
forensic scientists?
3. What are the characteristics of a typical
crime lab?
4. Which historical forensic scientists laid the
ground work for modern forensic science?
5. What is the importance of Locard’s
Exchange Principle?
ESSENTIAL QUESTIONS
6. What is the basic methodology used by
forensic scientists?
7. What are the steps that must be followed
in the pursuit of justice?
8. What is the importance of the Federal
Rules of Evidence?
9. What is the importance of the Frye
Standard?
10.What is the importance of the Daubert
Ruling?
Sequence of Events
1) Introduction to Forensic Science and the Law
2) The Crime Scene
3) Fingerprint Analysis
4) Hair and Fiber Analysis
5) Soil and Glass Analysis
6) Handwriting and Document Analysis
7) Forensic Pathology
8) Forensic Toxicology
9) Forensic Serology and DNA Analysis
10)Firearms, Toolmarks and Impressions
11)Arson and Explosives
Forensic Science is…
the application of science to those criminal
and civil laws that are enforced in a
criminal justice system.
Criminalistics is…
the examination of physical evidence
Forensic scientists use crime
labs to help them examine…
EVIDENCE –
anything that tends to establish or disprove
a fact
• documents
• testimony
• objects
Forensic Specialties
Anthropology (human remains)
Psychiatry (mind)
Odontology (bitemarks)
Engineering (structural failures)
Computer Technology (data recovery)
Pathology (death)
Geology (earth)
More Specialties
Environmental Science (human effect on earth)
Entomology (insects)
Palynology (pollen & spores)
Polygraphy (lie detector)
Voiceprint Analysis
A forensic scientist’s main job is to
study the different types of evidence
found at a crime scene, but s/he must
also testify as an expert witness,
perform scientific research and train
others.
Crime Laboratories
• There are ~ 350 crime labs in US
– Federal, state, county, and municipal (local)
– Most function as part of a police department
– Others fall under direction of the prosecutor or
district attorney’s office
– Some work with labs of the medical examiner
or coroner
– A few are affiliated with universities or exist as
independent agencies in government
• Most labs are maintained by states for
regional areas
– GBI has 7 regional labs;
– Eastern Regional Lab is located in Augusta
and serves 15 counties
There is NO national system of forensic
laboratories
So…
there is little organization and
consistency among US forensic labs
Crime Lab Departments
• Physical Science
– Chemistry (drug analysis) *
– Trace Evidence (hair, fiber, soil, glass, paint, GSR)
• Biology (blood, DNA, cells) *
• Firearms (ballistics, toolmarks) *
• Questioned Documents (handwriting, documents,
impressions)
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•
•
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Photography
Toxicology (drugs/alcohol/poisons in bio. samples) *
Fingerprints
Pathology (manner/cause of death)
Crime Lab Statistics
• State funded labs have a budget of ~$1 bil.
• Average salary for an analyst is ~$50k/yr
• ~90% of all analyses are for controlled
substance ID
• ~20% of cases are backlogged (>30 days)
– most are DNA analyses
• Oldest lab in world is in Lyons, France (1910)
• Oldest lab in US is LAPD (1923)
Federal Forensics Labs
• Federal Bureau of Investigation
– Largest in the world
– Located in Quantico, VA
– Operated by the Department of Justice (DOJ)
• Drug Enforcement Agency
– Drug-related crimes
– 21 regional divisions
– Operated by the DOJ
Federal Forensics Labs
• Bureau of Alcohol, Tobacco, Firearms,
and Explosives
– Crimes involving alcohol, tobacco, firearms,
explosives, suspected arson, and organized
crime
– National Laboratory Center located in
Beltsville, MD
– Operated by the DOJ
Federal Forensics Labs
• United States Postal Inspection Service
– Crimes involving the mail
– Located in Dulles, VA
– Operated by the United States Postal Service
• United States Fish & Wildlife Service
– Crimes against wildlife
– Located in Ashland, OR
– Operated by the Department of the Interior
• Orfila (1814)
Founding Scientists
– Father of forensic toxicology.
– First treatise on detection of poisons and their effects on
animals.
• Bertillon (1879)
– Father of criminal identification
– Developed the science of anthropometry—the taking of
body measurements as a means of distinguishing
people.
• Galton (1892)
– First statistical proof supporting the uniqueness of
fingerprints.
• Gross (1893)
– Father of criminalistics
– First treatise describing the application of science to the
field of criminal investigation
• Locard (1910)
– Father of forensic science.
– Developed the idea of cross-transfer of evidence
• Osborn (1910)
– Developed the fundamental principles of document
examination.
• Lattes (1915)
– Developed a procedure to ID blood groups from dried
bloodstains.
• Goddard (1925)
– Refined the techniques of bullet ID with the
comparison microscope.
• McCrone (1977)
– Perfected the use of the microscope in forensic
investigation.
Methodology
• Locard’s Exchange Principle
“Whenever two objects come into contact, there
is always a transfer of material. The methods
of detection may not be sensitive enough to
demonstrate this, or the decay rate may be so
rapid that all of the evidence of transfer has
vanished after a given time. Nonetheless, the
transfer has taken place.”
Methodology
• The Scientific Method
1. Observe a problem or questioned
evidence and collect objective
data
2. Consider a hypothesis or possible
solution to the problem based on
observation.
•
This step requires inductive reasoning
(specific  general), experience, and
imagination.
Methodology
3. Examine, test, and analyze to
support or refute the hypothesis.
4. Use deductive reasoning (general
 specific) to make a determination
as to the significance of the
evidence.
Methodology
5. Evaluate and verify all evidence.
•
This step is especially critical to a forensic
scientist because someone’s liberty can
be at stake.
6. Develop a theory or opinion that is
able to stand up to scientific and
legal scrutiny.
Criminal Justice and the Law
US Constitution is the supreme body of laws
that trumps all
• Statutory Law (legislation)
– Enacted by a governmental body or agency
having the power to make laws (such as
Congress)
• Common Law (case law)
– Made by judges
– Precedents allow for consistency and
predictability in how the law is applied
• Civil Law (code law)
– Collection of codified statutes
– Precedents are given less weight
– Deals with relationships between individuals
– More concerned with assigning blame than
with establishing intent
– “Preponderance of evidence” is required to
convict
• Criminal Law (penal law)
– Body of rules that defines conduct prohibited by
the state and assigns punishment for breach
– Punishments are related to the “guilty act” and
the “guilty mind”
– Distinguished between “major” and “minor”
crimes
– “Beyond a reasonable doubt” is required to
convict
Steps in Pursuing Justice
• Once a crime is committed and discovered…
– A suspect may be identified
– Police investigate what may have happened
– Information is collected
– Crime scene is documented and searched for
evidence
– Info is assembled into a report for the prosecutor
– Investigation ensues
– If enough evidence can establish probable
cause, then an arrest warrant is issued
• After a suspect has been arrested…
– S/he is booked, fingerprinted,
photographed, and informed of his/her
Miranda rights
– Brought before a judge within 48 hrs for
arraignment to hear charges and enter a
plea
• After a defendant’s plea is made…
– A preliminary hearing is conducted
before a judge
• This is to determine whether there is
enough evidence to proceed to a trial
• Probable cause must be established
– Federal gov’t and some states may use
a grand jury for felony cases
• Defendant is not entitled to counsel
• Pleading “not guilty by reason of
insanity”…
– Requires the defendant to prove the
inability to “know right from wrong” at the
time of the commission of the crime
– It removes the requirement to
demonstrate intent
• A person is presumed innocent until
proven guilty
– The burden of proof rests with the
prosecution
– Only 50% of all arrests lead to
conviction
– Only 25% of all convictions are
sentenced to 1+ years in prison
• Plea bargaining can reduce the burden on
the court by allowing a defendant to plead
guilty to a lesser charge and avoid a trial
– 90% of all cases are “pleaded down”
Types of Crimes
A broken law is called a violation.
• INFRACTION “regulatory offenses”
– Least serious class of crime
– Can be proceeded against without the right to
a jury trial and/or indictment
– Punishable by fines
– Include traffic tickets/violations, jaywalking,
littering, disturbing the peace
• MISDEMEANOR
– More serious class of crime than infraction
– Punishable by 1 year or less in prison, housearrest, probation, community service…
– Include petty theft, prostitution, public
intoxication, disorderly conduct, trespassing…
• FELONY
– Most serious class of crime
– Punishable by more than 1 year in prison or
by death
– Include aggravated assault/battery, arson,
burglary, grand theft, robbery, murder, rape…
Federal Rules of Evidence (1975)
• To be acceptable in court, evidence must
be RELEVANT; that is, it should be both
MATERIAL and PROBATIVE.
– Material evidence has some logical
connection to a fact of consequence to the
outcome of a case
– Probative evidence can prove or disprove
legal elements of the case
• The forensic scientist, or expert witness,
has an obligation to be an advocate for the
truth, and should not take sides for either
the defense or prosecution.
• The person who presents scientific
evidence must establish credibility via
credentials, background, and experience.
The Frye standard
(Frye vs. US, 1923)
• Frye was convicted of murder. On appeal,
defendant’s counsel offered an expert witness to
testify to the result of a deception (pre-polygraph)
test, claiming that during the first trial, the
testimony was not accepted.
• SCOTUS let the conviction stand and stated that
scientific evidence must have gained “general
acceptance” to be accepted in court
– At that time, the deception test was not “generally
accepted”…
The Frye standard
– Commonly called the “general acceptance”
test
– Dictates that scientific evidence is admissible
at trial only if the methodology or science is
“generally accepted” in the field of study
– Only applies to new science/technologies
The Daubert standard
(Daubert vs. Merrell Dow Pharmaceuticals, 1993)
• Daubert family sued Dow claiming that
children’s birth defects had been caused
by mother’s prescription drugs
• The trial court decided that evidence did
not meet the Frye Standard
• In appeals, SCOTUS decided that the
Frye Standard was no longer appropriate
because of technological sophistication
The Daubert Ruling
– The judge is the “gatekeeper”
– Applies to federal courts
– Endorses the classical definition of the
Scientific Method
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Hypothesis testing
Estimates of error rates
Peer-reviewed publication
General acceptance
Technique standardization