Ch. 6 Flashcards
When does evidence collection and preservation begin?
After the completion of documentation and search for evidence
How many people should be the evidence officers?
1
What evidence should be collected first?
Fragile, easily lost or transient evidence
What should physical evidence be placed in?
A primary container, and then a secondary container
What makes up the most important category of physical evidence for positive identification?
Fingerprints
What can make a print?
Fingers, palms, feet, lips, and ears
What forms can prints be found in?
latent, plastic, visible, and wet
What is the most common light use?
Side lighting
What are different sources of light?
High power flashlight, portable laser, forensic light source
What is the first step when a print is found?
Photograph
What should be done after a print is photographed?
Enhance it based on the type of print found and the surface it is on
What happens if a print is found on an immovable or large object?
Field processing is warranted
What happens if a print is found on a small, moveable object?
The object can be packaged for collection
What is the general fingerprint processing procedure?
Visual Search Photograph Enhancement Photograph Lifting/collection
Latent prints are also known as:
Invisible prints
What is done to latent prints when they are found at the crime scene:
Enhanced/visualized by physical, chemical, instrumental, or a combination of methods
What types of surfaces are fingerprints found on that require a physical method of enhancement?
dry, non-pours surfaces like glass or plastic
What methods are involved when developing prints by physical means?
Colored powders and brushes
What is the most common physical method used for a light color background?
Black powder
Magna powder
Used for shiny surfaces like plastic bags, CD cases, or magazine covers
What happens after a latent print is visualized?
Photograph it
Where is a lifted print placed?
On a backing card
The lift card/backing card becomes:
evidence
Chemical processing can be used to enhanced latents on….
wet and dry surfaces
What is the best chemical method for dry surfaces?
Various dye staining techniques
What is used to develop latents on wet surfaces?
small particle reagent spray
How are latent prints on porous surfaces visualized?
the use of chemical methods
What are some examples of chemical methods?
Silver nitrate, iodine fuming, and ninhydrin
How do visible prints come about?
They result when friction ridges are coated with something that is transferred to another surface leaving the outline or impression of the friction ridge
How should visible prints be recorded?
Photographed, and the object containing the print is packaged and collected, if possible
Enhancement of a Visible Print
Can be enhanced so better ridge detail can be obtained
Depends on the chemical composition of the transferred material
What is the most common visible print?
Bloody fingerprints
How do chemical reactions allow for a better visualization?
Change of color
Methodology for Processing Evidence with Bloody Fingerprints
Visual
Photograph
Amino black
Photograph
Plastic prints are also known as
3D prints
How are plastic prints produced?
When the friction ridges of a finger comes into contact with a softer surface
What is the best way to document an impression?
Photograph // casting
What is the purpose of elimination prints?
comparison
What is another word for elimination print?
Known print
Why would one be able to see a print on human skin?
Due to a contaminent
What are 2 techniques for developing or enhancing latent prints on a body?
Transfer lift method
Superglue fuming
What are two types of impression evidence ?
Imprints and indentations
Imprints
2D
Indentation
3D
How are imprint evidence created?
caused by material/residue from one surface transferred to a second
What are the most common types of imprints?
Fingerprints, footwear, tire tread
What can help one visualize imprint evidence?
Light sources
What is the issue with lifting imprint evidence on porous surfaces?
Not easy to do with tape; gel may be better
Enhancement Methods for Porous Surfaces
Iodine fuming, ninhydrin, blood enhancement
Enhancement Methods for Any Surface
Trace metal, oblique lighting, UV light, gel lifters, electrostatic
What is the best collection method for nonporous surface?
Gel lifters, electrostatic lifters, adhesive lifters
How are indentations created?
The softer surface becomes indented with the shape, length, width, ad depth of the harder item
What casing method do you use for hard / soft surfaces
silicone rubber material / dental stone
What is the importance of knowns?
Identify any class or individual characteristics due to the size, pattern, and wear characteristics
Hair evidence
used to identify race and somatic origin of the source
How is hair evidence collected?
Using tweezers and placed into a druggist fold; same location can be packaged together
How many hairs should be collected?
25-50 from different regions of the body
