The Crime Scene - PowerPoint PPT Presentation

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The Crime Scene

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Photography. Overview photography. Of entire scene and surrounding area ... Increasingly popular because of decrease in cost of equipment. ... – PowerPoint PPT presentation

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Title: The Crime Scene


1
The Crime Scene
  • Forensic Science Honors

2
Processing the crime scene
  • Crime labs run on physical evidence.

3
Physical Evidence
  • Encompasses any and all objects that can
    establish that a crime has been committed or can
    provide a link between a crime and its victim or
    a crime and its perpetrator.
  • To be used, physical evidence must be recognized
    at the scene.

4
Physical Evidence
  • Collection is performed with a selectivity
    governed by the collectors thorough knowledge of
    the crime labs techniques, capabilities, and
    limitations.
  • Forensic Analysis begins at the crime scene.

5
Processing the Crime Scene
  • With proper training, police agencies can ensure
    themselves of competent performance at crime
    scenes.
  • In many jurisdictions, police agencies have
    delegated this task to a specialized team of
    technicians.

6
Physical Evidence
  • Not all crime scenes require retrieval of
    physical evidence.
  • In reality, limited resources and personnel have
    forced many police agencies to restrict their
    efforts to crimes of a more serious nature.
  • Once the commitment is made to completely process
    a crime site for physical evidence, it is
    imperative that certain fundamental practices be
    adhered to.

7
Secure Isolate the crime scene
  • First officer on the scene is responsible for
    preserving and protecting the area to the
    greatest extent possible.
  • The first priority is
  • Obtaining medical assistance for individuals in
    need.
  • Arresting a perpetrator
  • Ensuring safety

8
First Officer
  • As soon as possible should exclude all
    unauthorized personnel from the scene.
  • As additional officers arrive
  • Measures are immediately initiated to isolate the
    area.
  • Ropes or barricades and strategic position of
    guards to prevent unauthorized access.

9
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10
Access
  • If proper control is to be exercised over the
    crime scene, the officer charged with the
    responsibility of protecting it must have the
    authority to exclude everyone, including fellow
    police officers not directly involved in
    processing the site or in conducting the
    investigation.

11
Scene secured
  • Once the scene has been secured, a lead
    investigator will start the process of evaluating
    the area.

12
Evaluating the area
  • First the boundaries of the scene must be
    determined.
  • Second establish the path of entry and exit of
    the perpetrator

13
Evaluating the area
  • The obvious items of crime scene evidence will
    first come to the attention of the investigator.
    These must be documented and photographed.
  • The investigator then proceeds with an initial
    walk-through of the scene.

14
The Walk-through
  • The walk-through is done to gain an overview of
    the situation.
  • It also gives the investigator the opportunity to
    develop a strategy for the systematic examination
    and documentation of the entire crime scene.

15
Recording the Scene
  • There is only a limited amount of time to work a
    crime site in its untouched state.
  • The investigators must permanently record the
    scene in its original state.
  • Useful in investigation
  • Required for presentation at trial
  • Documents the condition of the crime site
  • Delineates the location of physical evidence.

16
Recording the Scene
  • Three methods of crime scene recording
  • Photography
  • Digital
  • Traditional
  • Sketches
  • Notes

17
Photography
  • The most important prerequisite for photographing
    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.

18
Photography
  • If objects are removed, positions changed, or
    items added, the photographs may not be
    admissible in court.
  • The fact of the change must be noted in the
    report.
  • Evidence should not be reintroduced for
    photographing.

19
Photography
  • Crime scene should be photographed as completely
    as possible.
  • Crime scene should include the area in which the
    crime took place and all adjacent areas where
    important acts occurred.

20
Photography
  • Overview photography
  • Of entire scene and surrounding area
  • Including points of exit and entry
  • Taken at various angles

21
Photography
  • If the crime is indoors
  • Entire room show each wall area
  • Rooms adjacent must be similarly photographed
  • If it includes a body
  • Show bodys position and location relative to
    scene
  • Close up photos depicting injuries and weapons
    lying near body

22
Photography
  • After body is removed
  • Scene beneath the body

23
Photography
  • As items of physical evidence are discovered
  • Photographed to show their position and location
    relative to the entire scene
  • Close-ups to record the details of the object
  • When size is significant
  • A ruler or other measuring scale may be inserted
    near the object
  • Included in the photo as a point of reference

24
Photography
  • Digital photography
  • Enhances photographic capabilities
  • Individual images of the crime scene can be put
    together electronically to reveal a near-3D
    panoramic view of the crime scene

25
Digital Photography
  • With the aid of a computer any scene can be
    enhanced and examined in fine detail.
  • Digital photography has a lower cost than
    traditional photography.
  • It can be uploaded and transmitted quite easily.

26
Photography
  • Videotape
  • Increasingly popular because of decrease in cost
    of equipment.
  • Should include entire scene and immediate
    surrounding area.
  • Long shots and close-ups should be taken in a
    slow systematic manner.

27
Video Photography
  • Desirable to have investigator narrate the events
    and scenes while another takes the pictures.
  • Cannot be used in place of still photography.

28
Sketches
  • Are done after photos are taken
  • Do not require art skill only accuracy

29
Sketches
  • Rough sketch
  • Required
  • Contains an accurate depiction of the dimensions
    of the scene
  • Shows the location of all objects having a
    bearing on the case
  • Shows all recovered items of physical evidence
  • Other important features of the scene

30
Sketches
  • Objects are located in the sketch by distance
    measurements from two fixed points such as the
    walls of a room.
  • Accuracy of measurements is important cannot be
    an estimate
  • Measurements should be made with a tape measure
  • Simplest way to designate an item assign a
    number or letter.

31
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32
Sketches
  • A legend or list placed below the sketch will
    correlate the letter to the items description.
  • Show a compass heading designating north.

33
Sketch
  • Finished sketch
  • Unlike a rough sketch this one is drawn with
    care and concern for aesthetic appearance.
  • Prepared with the aid of templates and drafting
    tools by a skilled individual
  • Drawn to scale
  • Must reflect information contained within the
    rough sketch in order to be admissible in court

34
Computer programs
  • Are becoming available to reconstruct crime
    scenes with computer-aided drafting (CAD)

35
Computer Programs
  • Contain pre-drawn intersections and roadways
  • Contain pre-drawn buildings and rooms
  • Information can be added on top of these
    templates to personalize the scene

36
Computer Programs
  • Contain symbol libraries these are a variety of
    images that can be used to add intricate details
    such as blood splatter.
  • A good program will be equipped with a zoom
    function allowing you to focus on a specific
    area for a more detailed picture.

37
Computer Programs
  • Allow you to select scale size.
  • The ultimate product can be produced in a size
    suitable for courtroom presentation.

38
Taking Notes
  • Must be a constant activity throughout the
    processing of the crime scene.
  • Must include a detailed written description of
    the scene. Must include the location of items of
    physical evidence recovered.

39
Taking Notes
  • Must also identify the time an item of physical
    evidence was discovered
  • By whom
  • How and by whom it was packaged and marked
  • Disposition of the item after it was collected

40
Taking Notes
  • This written record may be the only source of
    information for refreshing ones memory months
    or years after the crime has been processed.
  • Notes must be sufficiently detailed to anticipate
    this need.

41
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