The Evidence
Forensic Science:
Fundamentals and
Investigation
1
Bertino
Packaging the evidence
Crease a clean paper and
place evidence in the X
position
2. Fold in the left and right sides,
and then fold in the top and
bottom
3. Put the bindle into a plastic or
paper evidence bag affixing a
seal over the opening
4. Write your name on the seal
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Forensic Science: Fundamentals & Investigations, Chapter 2
Avoiding Contamination
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Contamination is a key concern during
the collection of DNA-containing
specimens such as blood, saliva, sweat
or skin cells. Contamination can occur
either by introducing foreign DNA
through coughing or sneezing onto
evidence or if items of evidence are
incorrectly placed in contact with each
other during packaging.
Forensic Science: Fundamentals & Investigations, Chapter 2
Evidence ID Forms
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Forensic Science: Fundamentals & Investigations, Chapter 2
Chain of Custody
Maintaining a chain of custody log is essential to
present credible evidence in court
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Forensic Science: Fundamentals & Investigations, Chapter 2
Chain of Custody (cont’d.)
1. Bag the evidence
Add identification
Seal it
Sign it across the sealed edge
2. Sign over to a lab technician
Open bag on non-sealed edge
3. Return items to the evidence bag
Seal evidence bag in another
bag
Sign the evidence log
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Forensic Science: Fundamentals & Investigations, Chapter 2
Reference Samples
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Standard/Reference Sample
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Physical evidence whose origin is known,
such as blood or hair from a suspect, that
can be compared to crime-scene evidence.
Forensic Science: Fundamentals & Investigations, Chapter 2
Leaving the Scene
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The experienced lead investigator
decides when all pertinent physical
evidence has been recorded and
collected at the crime scene.
A final survey is undertaken to visually
review the scene and collect all
evidence and equipment
Forensic Science: Fundamentals & Investigations, Chapter 2
Submitting the Evidence
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Most laboratories require that an
evidence submission form accompany
all evidence submitted. Case
information provided on this form
enables the laboratory analyst to make
an intelligent and complete
examination of the evidence.
Forensic Science: Fundamentals & Investigations, Chapter 2
Analyze the Evidence
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Facts result from collected evidence
processed by the forensic lab
Lead detective aims to see how facts fit into
the crime scenario
Forensic Science: Fundamentals & Investigations, Chapter 2
Analyze the Evidence
Lab results can:
o Show reliability of witness accounts
o Establish the identity of suspects or victims
o Show suspects to be innocent or link them
with a scene or victim
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Forensic Science: Fundamentals & Investigations, Chapter 2
Safety at the Crime Scene
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Crime scenes frequently present the
investigator with biological specimens
of unknown origin; the investigator has
no way of gauging what health hazards
they may contain. One must use
caution and protection at all times.
Forensic Science: Fundamentals & Investigations, Chapter 2
Search and Seizure
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The removal of any evidence from a
person or from the scene of a crime
must be done in conformity with Fourth
Amendment privileges:
Forensic Science: Fundamentals & Investigations, Chapter 2
SCOTUS Says….
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Search and seizure without a courtapproved warrant is justified in four
cases:
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The existence of emergency
circumstances
The need to prevent the immediate loss
or destruction of evidence
Forensic Science: Fundamentals & Investigations, Chapter 2
3.
4.
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A search of a person and property within
the immediate control of the person
provided it is made incident to a lawful
arrest
A search made by consent of the parties
involved
Forensic Science: Fundamentals & Investigations, Chapter 2
Search and Seizure Cases
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In the case of Mincey v. Arizona, the
Court dealt with the legality of a fourday search at a homicide scene and
determined that the evidence was
illegally seized because a warrant was
never issued and the circumstances of
the case did not justify a warrantless
search.
Forensic Science: Fundamentals & Investigations, Chapter 2
More Cases…
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In Michigan v. Tyler, fire destroyed a
business establishment leased by Loren
Tyler and a business partner. The court
decided that evidence obtained from
the initial search was legally seized, but
evidence obtained from searches 4, 7,
and 24 days after the incident were
illegally seized.
Forensic Science: Fundamentals & Investigations, Chapter 2