This method is helpful because the searcher is moving from an area light with evidence to an area where more evidence is most likely to be found. Because the searcher may not be able to complete a perfect spiral evidence could be missed. Wheel/ray search-employs several people moving from the boundary straight toward the center of the scene or from the center straight to the boundary. This is not preferred because areas between the rays are not searched. Quadrant/zone search-involves dividing the scene into zones or quadrants and team members are assigned to each section.
This method is best suited for scenes that cover a large area. 2. What is the difference between a primary and a secondary scene? A primary scene is one at which the original incident occurred. The secondary scene is a location that became part of the crime scene by activities after the initial incident, such as using a car to transport a body. 3. List three methods for crime scene recording. Notes, photography, and sketches. Notes-the notes should start by identifying the person who contacted the investigator, the time of the contact, and all preliminary information enclosed, including the case number.
Photography-crime scene photographs can show the layout of the scene, the position of evidence to be collected, and the relation of objects at the scene to one another. Photography is also important for documenting biological evidence in its original condition because this kind of evidence is altered during testing. Sketching-a sketch shows the layout of an indoor or outdoor crime scene and the relationship in space of all the items and features significant to the investigation. It is important to illustrate the location of collected evidence.
Sketching clarifies objects and features already described in notes or shown in photographs. 4. What are aperture and f-number? How does the aperture relate to the f-number and how does this affect the amount of light to which the film exposed? The aperture is the size of the diaphragm opening through which light enters the camera. The f-number is the diameter of the lens opening for light to pass through the camera. One adjusts the aperture by setting the f-number, which is equal to the focal length divided by the aperture.
Thus, the aperture and the f-number are inversely related. The lower the f-number setting, the wider the aperture and the more light it allows in. 5. What is the depth of field? How does a camera’s the f-number relate to a depth of field of the photographs it produces? The depth of field is the range of in the foreground and background of a photographic subject that are also relatively in focus. Landscape mode on a digital camera automatically selects higher f-stops to improve the depth of field when the background and foreground are important.
The portrait mode selects lower f-stops to decrease the depth of field and make the subject stand out clearly against a blurred background. 6. What should medium-range photographs taken at the crime scene show? What should appear in every medium-range photographs and why? Medium-range photographs should show the layout of smaller significant areas of the crime scene. The items that should appear in every medium-range photograph are evidence markers and they are to show the spatial relationship between and among pieces of evidence in greater detail than the overview photographs.