THE CRIME SCENE
Physical Evidence
• Goals
– Define physical evidence
– Discuss responsibilities of the first police officer
on the scene
– Explain the steps taken for thoroughly recording
the crime scene
Physical Evidence
• As automobiles run on gasoline, crime laboratories
“run” on physical evidence.
• Physical evidence encompasses any and all objects
that can establish that a crime has been committed or
can link a crime and its victim or its perpetrator
– Examples- Hair, skin, fibers, fingerprints, blood, DNA,
weapons, soil, glass, documents, etc.
Crime Scene Investigation
• Forensic science is an important element of the total
investigative process but is only one aspect, crime
labs do NOT solve crimes.
• If the investigator cannot recognize physical evidence
or cannot properly preserve it for examination, no
amount of sophisticated laboratory instrumentation or
technical expertise can salvage the situation.
Crime Scene Investigation
• What needs to be done to avoid crime scene
contamination?
• What are the issues
that we would run into
in investigating the scene?
The First Steps
• First priority should be given to obtaining medical
attention for individuals in need of it and to arrest
the perpetrator if he/she is there.
• As soon as it is possible, extensive efforts must be
made to exclude all unauthorized personnel from
the scene.
– Do you think this would be an easy task?
– Why is this important?
Step 1- Secure the Perimeter
Step 1- Secure the Perimeter
Step 1- Secure the Perimeter
• The first officer to arrive at the scene is responsible
for securing the perimeter.
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Make the scene large initially
Set boundaries
Look for footprints/ tire tracks
Physical evidence
Perpetrator entrance and exit route
Step 2- Record the Scene
Step 2- Record the Scene
• Using your iPad, please visit the following
website;
– http://www.forensicmag.com/articles/2009/08/cri
me-scene-photography-capturing-scene
Read the article and answer the following questions1.) When should the crime scene photographer
begin recording the scene?
2.) What should the photographer take photos of?
Step 2- Record the Scene
• Photography/video, sketches, and notes are the three
methods for crime-scene recording.
• Ideally all three should be employed; however, as is
often the case, personnel and monetary limitations
may prohibit the utilization of photography at every
crime site.
Photography/Video
• The most important prerequisite for
photographing/taping a crime scene is for it to be in
an unaltered condition.
• Unless there are injured parties involved, objects
must not be moved until they have been
photographed from all necessary angles.
Photography/Video
• Crime scenes should be photographed/taped as
completely as possible
– Area in which crime took place
• Distant, mid-range and close-up images
• “Four corners” of room/structure
• Points of entrance and exit
– Bystanders
– All adjacent areas
– Body positions
– Close ups of possible evidence
• Show their position and location relative the entire
scene
• When the size of an item is of significance, a ruler may
be inserted near the object and included in the
photograph as a point of reference.
Sketches
• Once photographs are taken, the crime-scene
investigator will sketch the scene.
• Rough Sketch —A draft representation of all essential
information and dimensions at a crime scene.
• This sketch is drawn at the crime scene.
• It shows all recovered items of physical evidence
• Measurements
• Includes doors, windows and furniture
Rough Sketch
Sketches
• Finished Sketch —A precise rendering of the crime
scene, usually drawn to scale.
• Unlike the rough sketch, the finished sketch is drawn
with care and concern for aesthetic appearance.
• Many times your final sketch is completed with CAD
Finished Sketch
Notes
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Note taking must be a constant activity throughout
the processing of the crime scene.
These notes must include a detailed written
description with the location of items of physical
evidence recovered.
Notes
• They must identify:
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The time an item of physical evidence was discovered.
By whom.
How and by whom it was packaged.
The disposition of the item after it was collected.
• Notes may be the only source of information for
refreshing one’s memory. (Can be taped and later
written)
Recording the Crime Scene
• Investigators have only a short amount of time to work a
crime site in its untouched state.
• Every step of the investigation should be recorded
thoroughly with an appropriate method.
• Such records will not only prove useful during the
investigation but are also useful for presentation at a trial
in order to document the condition of the crime site and to
show the location of physical evidence.
JonBenet Ramsey Case
• Crime Scene Investigation- Please underline
errors made in securing and processing the crime
scene.
• Initially, the police conducted a cursory search of
the house but did not find JonBenet. The house
was not sealed off. Four friends along with the
Ramsey pastor were let into the home and
allowed to move about at will. John was
permitted to leave the premises unattended for
an hour and a half. Once hour after his return,
John and two of his friends searched the house
again. This time John went down into the
basement where he discovered JonBenet’s body.
He carried her upstairs, placing the body on the
Crime Scene Investigation- Please underline errors made in securing
and processing the crime scene.