Transcript File

Introduction to Forensic
Science
The Science Behind Catching Criminals
Forensic Science
• Forensics is the application of science
to criminal and civil law enforced by
police in a criminal justice system
• It incorporates techniques of chem,
bio, physics, geology, computer tech
to determine value of crime
scene/related evidence
• Pathology, psychology, anthropology,
odontology used in areas of
knowledge and practice in law
enforcement
Criminalistics vs Forensics
Criminalistics
Forensics
reflects a purely
scientific approach to
examining crime
scenes & evidence
that will be for legal
justice.
uses a variety of
techniques & principles
to study evidence that
will be used in courts
of law.
uses biology,
chemistry, physics,
geology, etc (this is
what we will study)
uses not only science
but psychology,
accounting, computer
science, engineering,
etc.
Criminalistics is only a
part of Forensic
Science
Functions of the
Forensic Scientist
• Of 3 major avenues to solve a
crime (confession, eyewitness
accounts, physical evidence)
evidence is free of bias or error
• Analyze physical evidence
• May be required to testify at a
trial or hearing
• Train law enforcement in the
proper recognition,
collection, and preservation
of physical evidence
History
• One of earliest records Yi Yu Ji
(A Collection of Criminal Cases)
• Coroner solved a case
• Woman suspected of murdering husband,
burning the body-no ashes in mouth
• Burned 2 pigs and checked for ashes in
mouth
• Found ashes in pig that was alive before
burned
• No ashes in pig dead beforehand
• Guilty or not?
• Chinese also first to use fingerprints for ID
History
• 1798 “A Treatise on Forensic Medicine and
Public Health”
• 1775 Carl Wilhem Scheele?
• 1806 Valentin Ross?
• 1814 Mathieu Orfila?
• 1828 William Nichol?
• 1839 Henri-Louis Bayard?
• 1853 hemoglobin?
• 1863 blood?
• 1850’s and 1860’s photography?
History
• Father of Criminal Identification
• Alphonse Bertillon (1879)
• Anthropometry involved taking a
series of body measurements to
tell one person from another
• Was considered the most
accurate method for ID until
replaced by fingerprinting
Bertillon Measurements
History
• 1892 Francis Galton?
• 1893 Hans Gross?
• Best known figure in 19th century
Sherlock Holmes? Which newly
developed principles did he apply?
• 1901 Dr. Karl Landsteiner?
• 1910 Albert S. Osborn?
• 1915 Dr. Leone Lattes?
• Edmond Locard (1910) persuaded a police dept to
give him 2 attic rooms and assistants to start a police
lab
• "Wherever he steps, whatever he touches, whatever he
leaves, even unconsciously, will serve as a silent
witness against him.
• Not only his fingerprints or his footprints, but his hair,
the fibers from his clothes, the glass he breaks, the tool
mark he leaves, the paint he scratches, the blood or
semen he deposits or collects.
• All of these and more, bear mute witness against him
• This is evidence that does not forget. It is not confused
by the excitement of the moment.
• It is not absent because human witnesses are. It is
factual evidence.
• Physical evidence cannot be wrong, it cannot perjure
itself, it cannot be wholly absent. Only human failure to
find it, study & understand it, can diminish its value."
• Professor E. Locard, father of Locard's Exchange
Principle
History
Twentieth century:
• Dr. Walter C. McCrone?
• Army Colonel Calvin Goddard?
• 1984 Sir Alec Jeffreys?
• Computerized databases on
fingerprints, markings on bullets
and shell casings?
Overview
•
•
•
•
Organization of a Crime Laboratory
Services of the Crime Laboratory
Witnesses
Collecting Evidence
Crime Labs
• Are centers for both forensic
investigation of ongoing criminal
cases and research for new
techniques for the future
• FBI is the largest in the world
• Despite FBI lab, US has no
national system of forensic labs
• Many local law enforcement
jurisdictions (city, county, state)
run their own independent crime
labs
• Also can be run by DA, medical
examiner
4 Major Federal Crime Labs:
• FBI: offers more than a million exams a yr; used
to develop new testing methods; and, used to
train personnel
• DEA (Drug Enforcement Administration):
analyze drugs seized in violation of federal laws
• Bureau of Alcohol, Tobacco, Firearms, and
Explosives:
 analyze alcoholic beverages
 documents relating to alcohol &firearm excise
tax law enforcement
 Examine weapons & explosives
• U.S. Postal Inspection Service: has labs for
crime investigations related to postal service
5 Basic Services of Crime Labs:
Physical Science:
Uses chemical, physical,
and geological
techniques to identify/
compare crime scene
evidence
Examine drugs, glass,
paint, explosives, soil,
even drug ID, mineral
analysis
Biology Unit:
– Analyze:
• DNA profiling on dried
blood
• Body Fluids
• Hair
• Fibers
• Identify and compare
wood/plants
Firearms Unit:
– Analyze firearms, bullets,
casings, shotgun shells,
gunpowder residues on
garments, approximate
distance gun was fired
– Toolmarks
Document Examination Unit:
– Determine authenticity and
source of questioned documents
• Paper and ink analysis
• Handwriting
• Typewriting
• Indented writing
• Obliterations, erasures,
charred documents
Photography Unit:
Examine and record
physical evidence at a
crime scene
Can use digital
imaging, infrared, UV,
X-ray
Prepare photo exhibits
for court
Optional Services
• Toxicology: determine drug/poison
presence
• Latent Fingerprint: process and
examine fingerprints
• Polygraph: lie detector
• Evidence Collection:
collect/preserve evidence
• Voiceprint Analysis: tie voice to
suspect
Expert vs lay witness
• Expert: will need to be
educated, have experience,
and training relevant to the
trial. This person may
express personal opinions to
significance of special
findings
• Lay: must testify on events or
observations that come from
personal knowledge (must be
factual, no personal opinion
of witness)
Collecting evidence
• Get trained personnel to
the scene
• They are trained to
recognize and gather
evidence (CSI)
• Many police forces still
have not adopted this
approach
• If not, officer or detective
collects evidence
Forensic Careers
(some examples)
•
•
•
•
•
•
•
•
•
•
•
Criminalistics
Forensic Engineering
Forensic Odontology
Forensic Pathology/Biology
Forensic Anthropology
Forensic Psychology and Psychiatry
Forensic Drugs and Toxicology
Document Examination
Digital and Photography Analysis
Ballistics
Forensics Botany