Download Introduction to Forensic Science

Introduction to Forensic
Science

Forensic Science

 Involves the application
of scientific theory,
process, and techniques
in legal matters.
 Primary role of a
forensic scientist is to
analyze evidence
gathered at a crime
scene.
Science Disciplines Needed
Biology
Physics
Geology
Anthropology
Psychiatry
Photography
Toxicology
Ballistics
Odontology (in
forensics: examination
of bite marks and dental
identification of corpses)
 Engineering
 Chemistry
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 Computer technology
 Pathology
(investigation of a
sudden, unexplained
death)
 Environmental science
 Entomology (study of
insects, particularly
decomposers in
forensics)
 Palynology (study of pollen
and spores)
 Polygraphy (use of lie
detectors)
Locard’s Exchange
Principle

 Edmond Locard was a
pioneer in the field of
forensic science.
 He became known as “The
Sherlock Holmes of France.”
 In 1910, when he opened his
forensic lab, he stated that
whenever an individual
comes in contact with a
crime scene or victim, there
will be an exchange of
materials between them.
Two Types of Evidence

 Testimonial evidence:
prima facie evidence or
direct evidence, a
statement made by a
competent witness
under oath.
 Physical evidence: real
evidence; any object or
material relevant to a
crime.
Example of Physical
Evidence

 Hair, fibers, soil, glass,
body fluids,
fingerprints, pollen,
bones, toxic substances,
documents, firearms,
ammunition, gunshot
residues and
impressions (bite
marks, shoeprints, etc.)
Types of Physical Evidence

 Individual: linked to a
single source
 Examples: fingerprints
and footprints
 Class: Material that can
be linked to only a
group of items with
similar properties
 Examples: hair and
blood type
Two Forms of All Evidence

 Both testimonial or
physical evidence can be
either direct or
circumstantial evidence.
 Direct evidence: links the
suspect to the crime
 Examples: blood alcohol
content or possession of
an illegal substance
 Circumstantial evidence:
points to a possible
connection between the
evidence and the suspect
Forensic Evidence Databases

 The National Integrated
Ballistics Information
Network (NIBIN) allows
the comparison of
markings made by a
firearm on bullets and
cartridge casings.
 The International Forensic
Automotive Paint Data
Query (PDQ) contains
chemical and color
information pertaining to
original automotive
paints.
 SICAR (shoeprint image
capture and retrieval) is a
shoeprint database.
 The Integrated Automated
Fingerprint Identification
System (IAFIS), a
national fingerprint and
criminal history system
maintained by the FBI.
 The Combined DNA
Index System (CODIS)
enables federal, state,
and local crime
laboratories to
electronically exchange
and compare DNA
profiles.
The Crime Scene

 Forensics begins at the
scene of the crime.
 Careful, objective, and
scientific treatment of all
evidence must occur.
 If not, vital evidence may
be overlooked, damaged,
or contaminated; making
it useless in a court of
law.
Primary CSI Procedures
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1.
2.
3.
4.
5.
Interview
Examine
Photograph
Sketch
Process
1. Tag all evidence with
a number.
2. Photograph it.
3. Package it.
4. Label it.
Notes

 Police notes begin with your
assignment to the case and
continue to the end of the
investigation.
 Supplement all photos,
sketches, and scale drawings.
 Print with a smudge-proof blue
or black ink.
 Number and identify each page
with your name, title, case
number, and date.
 Record the time an action was
taken, information received, or
event was observed.
 Do not edit or erase. Line out
the entry, initial, and rewrite.
Forensic Photography

 No objects are removed
until they have been
photographed from all
necessary angles.
 Three ranges of picture
documentation:
 Overview
 Intermediate
 Close-up (close and
perpendicular to the
object.)
Photo Log Information

 Assign each photo a
number.
 Describe photo contents.
 Cite the time the photo
was taken, the type of
photo, and the distance to
the focal point.
 List the type of camera
used and the height at
which it was held.
Additional Photo Log

 List the position of the
camera or the angle of the
camera shot.
 List what lens was used;
whether a flash was used;
and whether digital or the
type of film.
 If film, note when new
film is loaded.
 Note all data on a photo
sketch, as well as in your
notes.
Crime Scene Sketches
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 Aerial view of the
entire crime scene
 Rough sketch vs.
finished drawing
Elements of Sketching
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Measurements
Compass directions
Essential items
Scale or proportion
Legend
Title (case-file # and offense)
Projection
Surveying methods
 Rectangular (hypotenuse)
or polar coordinates
(length and angle.)
Projection Drawing

 Looks like a box with
all four sides flattened.