Download Circumstantial evidence

Classification of evidence
• Evidence may be divided into two large
categories
1. Direct evidence-sworn statements that
directly establishes a fact
2. Circumstantial evidence-physical evidence
that does not directly establish a fact,
rather it requires that a judge/jury must
make inference from the evidence
presented.
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Introduction to Forensic Science
and the Law
Direct evidence: Eye witness accounts and
Confessions
• Why are eyewitness accounts and
confession classified as direct evidence,
although at times they have proven to
be very unreliable?
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Introduction to evidence
Circumstantial evidence
Physical Evidence/Tangible evidence
• Impression evidence- patterns should as shoe tracks,
tire impressions, tool marks, blood spatter, bite marks,
fingerprints etc. form a recognizable pattern that can be
compared to known patterns.
• Trace evidence-small evidentiary items such as hair,
fiber, paint chips, glass and soil that could place the
suspect at a crime scene or in contact with the victim.
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Introduction to evidence
Circumstantial evidence
•Circumstantial evidence can be divided
into three areas: physical, biological and
chemical evidence
•Physical Science evidence: tangible
evidence that relies on the use of physical
science
Examples: shoe and tire impressions, tool
marks, glass, ballistics, blood spatter,
automobile accidents, structural analysis
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Introduction to evidence
Circumstantial evidence
•Biological evidence: evidence that is
derived from once living organism
Examples: blood, saliva, semen, hair, corpse,
pollen, plants, urine
Chemical Evidence-Utilizes chemical test to
either extract or examine evidence
Examples: toxicology, paint analysis, fiber
analysis, chromatography, pH, spectroscopy
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Introduction to evidence
Circumstantial evidence
Biological forensic science services
• Botany-examination of plant residue or plant
fragments, pollen, seeds and soil
• Forensic Anthropology-identification of
human skeletal remain to determine age,
sex, race, injuries, cause and manner of
death, and time of death. (duties may also
include identify victims of mass disasters or
those interred in mass graves
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Introduction to evidence
Circumstantial evidence
Biological forensic science services
• Forensic Entomology-Application of the life cycles
of insects that feed on corpse to determine
approximate time of death. Use of insect habitat to
determine if a body had been moved
• Forensic Odontology (forensic dentistry)-matches
dental patterns with previous x-rays, dental casts, or
photographs in order to identify an unknown corpse
• Matches suspects teeth with bite mark on victim or
food products left at a crime scene
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Introduction to evidence
Circumstantial evidence
Biological forensic science services
• Forensic Pathologist-performs autopsy to
determine manner and cause of death, injuries
inflicted, when and how the injuries were inflicted.
• Compiles his information from police reports,
suspects and eyewitness accounts, and medical
records
• Forensic Psychiatry-studies and analyzes the state
of mind of perpetrators. Provides information about
the sanity of criminal to determine their competence
to stand trial, sign documents, or give informed
medical consent.
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Introduction to evidence
Circumstantial evidence
Biological forensic science services
•Serology- analyzes blood and other
body fluids such as semen, and saliva.
Blood typing, paternity testing, and DNA
profiling are performed by serologist.
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Introduction to evidence
Circumstantial evidence
Chemical science services
• Document Examination- analyzes questioned documents.
Questioned documents include documents whose age or
authenticity is in doubt, documents which may have been
altered.
• Document examiners use handwriting analysis to match
known samples to questioned documents or signature.
• Document examiners also examine the physical and chemical
properties of paper and ink.
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Introduction to evidence
Circumstantial evidence
Chemical science services
• Toxicology-study of drugs and poison. Duties include:
determining if drugs or poison is present both living and
deceased.
• Assess contribution of drugs or alcohol to aberrant behavior
or death.
• Identify confiscated drugs
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Introduction to evidence
Circumstantial evidence
Physical science services
• Fingerprint Examination unit- Perform analysis and
matching of an unknown fingerprint, palm and foot sole
print.
• Firearms Examination- often referred to as ballistics.
Examines weapons, ammunition, fired bullets,
shell casings, and shotgun shells.
• Firearms experts use microscope and various
chemical analyses in an attempt identify the
type of weapon and to match any fired bullets
or shell casings to a suspect weapon.
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Introduction to evidence
Circumstantial evidence
Physical science services
•Structural-deals with structures such
as buildings and bridges
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Introduction to evidence
Other Forensic Science Services
• Evidence collection unit-Also called Crime Scene
Investigation Unit (CSIU) functions in collecting and
preserving evidence from the crime scene and
transporting evidence to the lab
• Duties of the evidence collection team also includes: lifting
latent prints, collecting hair and fibers as well as other
articles at evidence located at the crime scene.
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Introduction to evidence
Other Forensic Science Services
• Evidence Storage unit- secure place for storing and
preserving evidence.
• Materials must be kept secure for years, or even decades
and the chain of custody must remain unbroken to
prevent the evidence from becoming compromised and
lose its evidentiary value.
• Photography unit-records the scene, all evidence and a
body (if one is present) with still photos as well as videos
which are crucial for crime scene reconstruction and
presentation of evidence in a courtroom.
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Introduction to evidence
Match each image to the specific physical evidence
unit
1.
2.
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Introduction to evidence
Other Forensic Science Services
• Match each image to the correct physical evidence
unit
3.
4.
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Introduction to evidence
Other Forensic Science Services
• Match each image to the correct physical evidence
unit
5.
6.
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Introduction to evidence
Other Forensic Science Services
• Match each image to the correct physical evidence
unit
8.
9.
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Introduction to evidence
Other Forensic Science Services
Additional videos for structural unit
http://www.huffingtonpost.com/2013/03/29/miamicollege-parking-garage-collapse_n_2979021.html
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Circumstantial evidence
1. Why does blood spatter evidence require
the application of physical science and
not biological science?
2. Why are items such as glass, paint and
soil considered trace evidence although
they are not usually very small?
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Circumstantial evidence
Homework
Refer to slides 6-15 and classify each type of
circumstantial evidence into one of the three
branches of forensics.
Example
Field
Medical
Laboratory
Botany
Psychiatry
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Forensic science vs Junk science
• Recently there has been debate
about what constitutes forensic
science
• Many of the physical evidence that
was once believed to be foul proof
have now been discarded as junk
science
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Forensic science vs Junk science
• In order for forensic evidence to
be considered as grounded in
science it must conform to the
steps of the scientific method
• We will view two video resources
to identify which commonly used
“forensic evidence” have now
come under scrutiny.
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