Transcript Forensic Techniques

Forensic Techniques
What is Forensic Science?
• Forensic comes from the Latin word
forensis.
• It means: for public discussion or
debate.
• Forensic science is science used in
public, in a court or in the justice
system. Any science, used for the
purposes of the law, is a forensic
science.
Forensic Scientists
• Television enhances the image of forensic
science.
• Forensic scientists are involved in all
aspects of criminal cases.
• The forensic scientist's goal is to use all
available scientific information to determine
the facts and, subsequently, the truth.
• The forensic scientist might determine:
– The validity of a signature on a will,
– If a corporation is complying with environmental
laws,
– The origin of physical evidence at a crime scene.
Forensic Scientists
• The facts developed by forensic scientists are based
on scientific investigation, not circumstantial
evidence or the sometimes unreliable testimony of
witnesses.
• The work of the forensic scientist can prove the
existence of a crime or makes connections to a
crime.
• The forensic scientist provides information and
expert opinion to investigators, attorneys, judges,
and juries which is helpful in determining the
innocence or guilt of the accused.
• Forensic scientists work closely with police officers,
sheriff's deputies, prosecuting and defense
attorneys, DEA, CIA, and FBI agents, immigration
workers, and crime scene investigators, to name a
few.
Techniques
• Forensic scientists use a variety of
techniques in their investigations.
• The next 8 slides provide examples of
forensic techniques.
Firearms and Toolmarks
• Typically, this includes matching
bullets to the gun that fired them.
• Toolmark identification involves the
identifying characteristics between
tools, such as a pry bar, and the object
on which it is used, such as a door
frame.
• Also included in the category are
explosives and imprint evidence.
Forensic Profiling
• When a specially trained psychiatrist or
investigator can examine certain crime
scenes to come up with a personality
profile of the offender.
Document Examination
• This discipline involves all special
relationships that may exist between
document and inscription and how it
relates to a person or sequence of
events.
• This includes forgery, counterfeiting,
and handwriting analysis.
Autopsy
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Done by a medical examiner
To determine cause of death
Includes external exam and photos
Followed by extensive internal exam:
– Organs are removed, weighed and
examined
– Tissues and fluids are analyzed for
abnormalities, presence of drugs, etc.
DNA Typing
• DNA code varies from one individual to
the next
• Scientists can link a strand of DNA to
an individual
• DNA can be identified from hair, blood,
or body fluid stains
• Provides powerfully compelling
evidence
Forensic Anthropology
• Examination of skeletal remains
• Tells if male or female, how the person
lived, past illness or debilitation, clues
to occupation
• Bones can tell us:
– Age at time of death
– Gender
– Race
– Height
Odontology
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Teeth – no other body part lasts longer
In fires, often the only thing remaining
No two people have identical teeth
Dental records are needed to compare
to the evidence
• Teeth useful in determining a subject’s
age
Blood
• Chemical test can determine if
substance (stains) is really blood
• Another test determines if it is animal
or human blood
• Can determine gender from blood
evidence