Chapter 9 - Basic Skills for Scene Processing Flashcards
Explain how the conversion of light is utilized as a Search tool in the crime scene.
Luminescence: the conversion of one wavelength of light to another. Used in various methods to search for a number of types of evidence.
The fingerprinting technique is based on the surface being examined. Identify and provide an example of the four basic surface types.
·porous surfaces: paper, cardboard, untreated wood
·nonporous smooth surfaces: varnished and painted surfaces, plastic services, glass
·nonporous rough surfaces: vinyl, leather, textured countertops, and other textured surfaces
·special conditions: anomalies such as human skin, adhesive tapes, and blood prints
Identify the purpose of fluorescent fingerprint powder and provide an example of when it is usedo
It provides greater contrast between the patent print and the substrate, useful on multicolored surfaces.
What is the primary reason for using the superglue fuming technique?
Superglue polymerizes (plasticizing) and stabilizes the latent prints.
What are the steps used to locate fingerprint evidence in fire scene evidence?
On nonporous items, exam with light for visible prints. If none, rinse any soot away and reexamine. If not soot is present, try applying LP powders. Photograph any visible or developed prints.
What are the steps used to photograph an impression prior to casting it?
What is the nature of the surface (wet, dry, does it hold contaminants)? Also, was the impression deposited by a wet or dry object?
Under what conditions is the electrostatic dust lifting device used?
Used only on dry surfaces. Can we use on almost any surface, both horizontal and vertical.
Under what conditions and for what purpose would a fixative spray be used when casting impression evidence?
Impressions made in extremely loose soil, powders, or sand may benefit from treatment by a fixative. Used to harden the impression to help it survive the pouring of the dental stone.
What are the steps used to cast an impression with dental Stone when the impression contains standing water?
When presented with an impression that has standing water in it, the technician slowly shift dental stone into the water rather than using wet-mixed dental stone.
What is the primary distinction between conditions where a gelatin lifter can be used compared with adhesive or rubber lifters?
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What is reflected light?
Reflected light defines the color of the things we visualize; for instance, blood absorbs all light rays except that of red. The red wavelengths are reflected back, and we visualize them as the color red.
White color represents a reflection of all light energy wavelengths, true or false?
True
Black color is the absorption of all light energy wavelengths, true or false?
True
In terms of light energy, what is the transmission of light?
Transmission of light relates back to its penetrating power; light energy can pass through an object. An object that has translucent or transparent properties is a good transmitter of light.
In terms of light energy, what is light conversion?
Light energy can be converted from one wavelength to another, creating the condition known as luminescence.
