Download Introduction to Forensic Science

Introduction to Forensic Science
Chapter 1
Chapter 1 Objectives
• To be able to define forensic science and
describe its various areas
• To be able to describe the major events in
the history of forensic science and relate
them to modern-day practice
• To be able to describe the duties of a
forensic scientist
• To be able to describe the organization of
federal, state, and local forensic science
laboratories
• To be able to diagram and describe the flow
of evidence through a crime laboratory
• To be able to describe the qualifications for
becoming a forensic scientist
• To be able to get information on careers in
forensic science
FORENSICS
• Today we use the term to
mean the methods of science
applied to matters involving
the justice system
• Which sciences are forensic
sciences?
– Any science can be a forensic
science if it has some
application to justice
– Criminalistics, Pathology,
Anthropology, Odontology,
Engineering, Entomology
CRIMINALISTICS
• The term can be used to describe the
comparative forensic sciences such as
fingerprints, questioned documents, firearms
and toolmarks
• Most commonly, however, criminalistics refers
to the myriad of types of physical evidence
generated by crime scenes
– Illicit drugs, blood and DNA, fire and explosive
residues, hairs and fibers, glass and soil particles,
paints and plastics, fingerprints, bullets, and much
more
PATHOLOGY
• Forensic pathologists determine the cause and
manner of death in cases where someone dies
under suspicious circumstances
• Cause of death – event that directly causes death
– Stroke, drug overdose, auto crash, poisioning, etc.
• Manner of death – the type of death (four only)
– Homicide, natural, accidental, and suicide
• Autopsy (or postmortem examination) is used to
make these determinations
• Pathologists work for medical examiners or
coroners (varies by state)
ANTHROPOLOGY
• Forensic anthropologists work with skeletal
remains
• If human, they determine from what part of the
body the bone originated
• If they have the correct bones:
– Gender, age, racial characteristics, and even
socioeconomic status can be determined
• If there is an injury to a skeleton or major bones,
the cause of the injury or death can be determined
• It is also possible to build a face onto a skull
using clay and pegs of various sizes
• Facial reconstruction helps find missing persons
ODONTOLOGY
• Odontology is a fancy name for dentistry
• Bite marks on a victim or other object can be
matched to a suspect
• Forensic odontologists can also help identify
remains from disasters such as plane crashes
– Postmortem dental records are taken and matched
to x-rays taken before death
• It is also possible to distinguish causes of facial
injuries
– Falling down the stairs vs. being struck by an
object
ENGINEERING
• Forensic engineers can be valuable in cases
where something has gone wrong with a
mechanical or structural entity or in cases of
automobile crashes
• Failure analysis is one of the major contributions
that forensic engineers make to the justice
system
• The majority of the work of forensic engineers is
in the investigation of traffic crashes
– Accident reconstruction is used to determine speeds,
directions of impact, and who was driving the
vehicle at the time of impact
ENTOMOLOGY
• Flies (usually blowflies) are usually the first to
arrive at a crime scene
• Flies and other insects lay their eggs in decaying
flesh
– Different insects do this at different times
– Other insects such as beetles and wasps will attack and
feed off the insects and eggs
• This parade of visitors takes place at surprisingly
consistent time intervals
• Forensic entomologists can estimate the postmortem
interval (how long ago death occurred)
• If a person has been poisoned or has overdosed, flies
and other insects will ingest this as well
Who Are Forensic Scientists?
• Two types:
– Enlisted (sworn police officers)
– Civilian
• As forensic science became more technical,
civilians were hired because it became difficult to
recruit scientists to be police officers
• Forensic scientists have very little function in
evidence collection and rarely attend crime
scenes
• Forensic scientists have two main duties:
– To analyze evidence
– To testify in court
Testifying In Court
• Lay witnesses testify as to what they have
perceived with their five senses
– They are not to give their opinions!
• Expert witnesses have knowledge or skills
from education or experience that qualify
them to give opinions and draw conclusions
• The judge decides if expert testimony is
needed and who is qualified to offer it
The U.S. Forensic Science System
• There are about 400 forensic science laboratories
in the U.S.
• Most federal crime labs are in the Department of
Justice under the control of the attorney general
• The FBI is know for having some of the most
prestigious forensic science laboratories in the
world
• The DEA has labs that analyze seized illicit drugs
• The secret service has labs to prevent harm to
protected people and to prevent counterfeiting and
credit card fraud
The U.S. Forensic Science System (2)
• The Department of the treasury has crime labs
• The BATF labs have some of the world’s leading
experts in fire and explosive analysis
• IRS crime labs specialize in the area of questioned
documents
– handwriting, typewriting and printers, inks, and papers
• The Dept. of the Interior has crime lab to
investigate poaching and hunting
• Each of the 50 states has a public crime lab
system and most have locally controlled facilities
Private Forensic Crime Laboratories
• Private labs
usually work for
the defendants
– Only the
prosecutor has
access to the local
or state public
laboratory
•The private labs perform a service to the criminal
justice system by providing resources for those
accused of crimes
Organization of Forensics Labs
• Typical forensic science labs have
– An intake section
– Analysis areas
– Other sections
INTAKE SECTION
• An intake officer logs evidence into LIMS and
affixes a barcode (Laboratory Information System)
• Chain of custody for physical evidence must be
authenticated
– There must be proof that the evidence seized at a
crime scene is the same evidence that appears in court
– An improper chain of custody can be grounds to
render evidence inadmissible
• Considerations are made before testing so that one
test does not ruin the conditions for another
– A gun may need to be test fired, fingerprinted, and
have blood removed. The order is important!
ANALYSIS AREA
• This is the familiar laboratory setting
• Each scientist will have a designated area of
the lab for evidence handling
• There are lots of instruments, glassware,
implements, and scientists in white lab coats
and safety glasses
OTHER LAB SECTIONS
• Some labs may have a garage where cars can
be kept for inspection and searching
• Many firearms sections have huge stainless
steel tanks that are full of water
– These are used to test-fire weapons for comparison
with bullets or cartridges from crime scenes
• Some large labs have collections of seized
weapons as well as ammunition
• There may also be interrogation rooms where
polygraph tests are performed
CAREERS
• Becoming a forensic scientist requires
education and training
–
–
–
–
–
Crime lab forensic scientist
Forensic pathologist
Forensic anthropologist
Forensic odontologist
Forensic Engineer
Crime Lab Forensic Scientist
• Entry level requirements include a
bachelor’s degree in chemistry, biology, or
forensic science and 1-2 years of experience
or a master’s degree with less experience
• The job market is very competitive and a
master’s degree is preferred
Forensic Pathologist
• Graduate from college with an excellent
academic record (4 years)
• Graduate from medical school (4 years)
• Complete a residence in pathology (4 years)
• Complete a residency in forensic pathology
(1 year)
Forensic Anthropologist
• Few crime labs can afford to hire a full-time
forensic anthropologist
• A lab may hire you full time if you have
another specialty (trace evidence, DNA
typing, etc.)
• Most obtain a Ph.D. and teach at a
university and handle cases part-time
Forensic Odontologist
• This is similar to the route for a forensic
pathologist except that you would complete
dental school instead of medical school
• There are very few residencies in forensic
odontology
• You would need to work with the police on
an as-needed basis
Forensic Engineer
• Require an education in engineering (the
more the better)
• Usually, Ph.D.s are in demand
• Most forensic engineers have their own
companies that are hired by prosecutors or
defendants