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September 2013
Introduction to Forensics
The Science Behind Catching Criminals
Mrs. Chanin-Bermudez
SUPA Forensics
• Definition of Forensic Science
 Scope
• History and Development of Forensics
• Organization of a Crime Laboratory
• Functions of the Forensic Scientist
 Analysis of Physical Evidence
 Provision of Expert Testimony
 Furnishing Training
• Scientific Admissibility
Definition and Scope of
Forensic Science
Forensic science is the application of
science to those criminal and civil laws
that are enforced by police agencies in
a criminal justice system.
Forensic Science: A
• Application of science to law
• Applies the knowledge and
technology of science for the
definition and enforcement of
such laws.
Forensic science is the application of
science to those criminal and civil laws
that are enforced by police agencies in a
criminal justice system.
• Alphonse Bertillon (1853-1914)
First scientific system of personal
Developed the science of
anthropometry, a systematic
procedure of taking a series of body
measurements as a means of
distinguishing one individual from
History and Development
Mathieu Orfila:
Father of
Galton: first
study of
(Nephew of
developed the
science of
for bullet
…more History
as a tool for
the forensic
Hans Gross:
Developed the
application of
principles to
Bertillon Measurements
History, Con’t
• Edmond Locard (1877 -1966)
Locard’s Exchange Principle –the
exchange of materials between two
objects that occurs whenever two
objects come in contact with one
another. A cross-transfer of
evidence occurs.
Organization of the Crime Lab
• Over 320 public crime labs in the
U.S…a tripling of the number
since 1966.
• Supreme Court decision Miranda
v. Arizona (1966)
• Increase in drug abuse
• Advent of DNA profiling
• Most State Governments maintain
crime labs plus satellite labs.
Organization of Crime Labs
• General Organization
No nationally organized system—
crime labs mirror the fragmented
law enforcement structure that that
exists on national, state, and local
• National Level
four major federal crime labs, FBI,
DEA, ATF, US Postal
Organization, Con’t
• FBI (Department of Justice)
Largest crime lab in the world
Broad investigative powers
• DEA (Drug Enforcement Agency)
Responsible for the analysis of
drugs seized in violation of laws
regulating the production, sale, and
transportation of drugs
Organization, Con’t
• ATF (Bureau of Alcohol, Tobacco,
Firearms, and Explosives)
Responsible for the analysis of
alcoholic beverages, weapons, and
explosives in conjunction with the
Gun Control Act and Organized
Crime Control
Organization, Con’t
• State Level
Most state governments maintain a
lab to service state and local law
Some larger cities maintain their
own crime lab, usually under the
direction of local police dept.
Organization Con’t
• Local Level
Local labs provide services to
county and municipal agencies.
Generally, they operate
independently of state labs and are
financed by local government.
Services of the Crime Lab
• Physical Science
• Biology Unit
• Firearms Unit
• Document
Examination Unit
• Photography Unit
• Toxicology Unit
• Latent Fingerprint
• Polygraph Unit
• Voiceprint Analysis
• Evidence Collection
Physical Science Unit
Physical Science Unit
• Investigators:
• Chemists
• Physicists
• Geologists
• Items Identified:
• drugs, glass, paint, explosives and soil
• Job:
• Analytical and chemical analysis
Biology Unit
Biology Unit
• Investigators:
• Biologists
• Biochemists
• Identify and Compare:
• botanical materials such as wood and
• Job:
• Identification and DNA profiling of dried
blood stains, other body fluids,
comparison of hairs and fibers
Firearms Unit
Firearms Unit
• Identify and examine:
Discharged bullets
Cartridge cases
Shotgun shells
• Responsibility:
• Examination of garments to detect
firearm discharge residue
• Determine approximate distance from
target when weapon was fired.
Document Analysis Unit
Document Analysis Unit
• Identify and Examine:
• Handwriting and typewriting to
determine authenticity and/or source
• Job:
• Analysis of paper and ink and indented
writings (impressions)
• Recreate:
• Obliterations, erasures
• Burned or charred documents
Photography Unit
Photography Unit
• Examine and Record:
• Physical evidence at the scene
• Specialize in:
• Digital imaging, IR, UV, and X ray
photography to make invisible
information visible to the naked eye
• Beyond the Scene:
• Preparation of photographic exhibits for
courtroom presentation.
Can you find the
Toxicology Unit
• Investigators:
• Chemists
• Biologists
• Examine:
• Body fluids and organs for the
presence or absence of drugs and
• Determines Blood alcohol content
• Job:
• Works with the coroner or medical
Latent Fingerprint Unit
Latent Fingerprint Unit
• Process and examine:
• Fingerprints to determine possible
matches with victims and suspects
Polygraph Unit
Polygraph Unit
• Job:
• Analyze respiration, perspiration, blood
pressure and pulse rate to determine
• Used in conjunction with
interrogation to determine
credibility of suspects and
Voiceprint Unit
Voiceprint Unit
• Interpret:
• Telephone threats
• Analyze:
• Tape recorded messages
• Compare:
• Suspect voice recording to evidence to
match source
Evidence Collection Unit
Evidence Collection Unit
• CSI:
• Crime Scene Investigation
• Consists of:
• trained personnel who are dispatched
to the crime scene to collect and
preserve physical evidence.
• They simply collect the evidence,
Locard’s Principle Revisited
• Attempt the Hypothetical Case with a partner.
• Answers:
– Victim was inside the car means fibers from its interior
have been transferred onto the victim’s clothing.
– Blood from the victim has been transferred onto the velour
– Fiber, blood, hair, and skin cells may also have been
transferred between the criminal and victim.
– Tire tracks from the car may have been left in the woods.
– This would probably lead to the make of car, since the tires
are special.
– If the vehicle was located, small driving imperfections in
the tread could link it to the crime.
– The type of soil at the crime scene may still be on the car’s
tires, too.
– Interior of suspect’s car could be tested for the fibers, hair,
skin cells and blood of the victim.
Functions of the Forensic
• Frye v. United States: 1923 Rejection of Lie
Detector (Polygraph) results necessitated
guidelines for determining judicial
admissibility of scientific examinations.
• The Frye Standard: The court must decide if
the questioned procedure, technique or
principles are “generally accepted” by a
meaningful segment of the scientific
Daubert v. Merrel
• Whether the scientific technique or theory
can be tested.
• Whether the technique or theory has been
subject to peer review and publication.
• The technique’s potential for error.
• Existence and maintenance of standards
controlling the technique’s operation.
• Whether the scientific theory or method has
attracted widespread acceptance within a
relevant scientific community.
Coppolino v. State
• M.E. testified that victim died of an overdose of
a drug called succinylcholine chloride based on
his toxicology report.
• Succinylcholine chloride breaks down into
succinic acid in the body.
• This drug had never before been detected in a
human body.
• Defense argued that this test was new and
absence of corroborative experimental data by
other scientists.
• The court rejected the defense’s argument on
the grounds that although the tests may be
new and unique, they are admissible only if
they are based on scientifically valid principles
and techniques.
Expert Testimony
• Must be competent: education degrees, member
of applicable societies, published papers or books,
• Defense may cross-examine the
potential expert witness.
• The individual trial judge is the
ultimate decision maker
regarding expert witnesses.
Training in Recognition, Collection, and
Preservation of Evidence
• Specially trained evidence collectors:
• On 24-hour call to aid criminal
investigators in retrieving evidence
• Specially equipped with all the proper
evidence collection equipment
• Unfortunately, some police forces still
don’t use them or the police themselves
have contaminated the crime scene
before the CSI team gets there!
Forensic Pathology
• Investigation of sudden, unnatural,
unexplained, or violent death.
• Medical Examiner vs Coroner = M.D. vs
political appointee.
• Autopsy:
• Causes of death: natural, homicide, suicide,
accident, undetermined.
• Rigor mortis: starts within the first 24 hours
and disappears after 72 hours. Helpful in
estimating time of death. See “Algor mortis”
• Livor mortis: settling of blood after the heart
stops. Skin appears dark blue. Used to
determine position of body at time of death.
Other Areas involving
• Anthropology: Examination of human
skeletal remains
• Entomology: insect life span can be
used to determine the time of death.
• Psychiatry: competency of suspect;
serial killed profiles
• Odontology: body identification
based on dental records; evidence
using bite marks left on victims
• Engineering: accident reconstruction
to determine causes
Services of the Crime Lab
Functions of the Forensic
• Analysis of Physical Evidence
 Applies the principles and techniques of
the physical and natural sciences to the
analysis of evidence
 Must be aware of the demands and
constraints of the judicial system
 Scientific procedures and techniques must
satisfy the criteria of admissibility
established by the courts
Functions Con’t
• Provision of Expert Testimony
May be required to testify with
respect to methods and conclusions
at a trial or hearing.
• Furnish Training
Train law enforcement in the proper
recognition, collection, and
preservation of physical evidence
Scientific Admissibility
• Frye Standard
 Court must decide if a questioned
procedure, technique, or principles are
“generally accepted” by a meaningful
segment of the scientific community
 In practice, this has meant providing
experts to testify that the procedure is
generally accepted
 Courts have also taken note of books,
papers, and past judicial decisions in this
Admissibility, Con’t
• Daubert Standard
 Court decides on the admissibility of
science in the courtroom
 “General Acceptance” is not an absolute
prerequisite for admissibility
 To ascertain the veracity of scientific
evidence presented the judge should use
the following areas of inquiry
Daubert Criteria
• Technique or theory can be (and has been)
• Technique or theory has been subject to peer
review and publication
• Technique’s potential rate of error
• Existence and maintenance of standards
controlling the technique’s operation
• Method or theory has attracted widespread
acceptance within a relevant scientific