Chapter 4 Flashcards
Characteristics of physical evidence that are common to a group of objects or persons are termed:
An individual identification cannot be made because there is a possibility of more than one source for the evidence.
Class Characteristics
This type of evidence can be identified, with s high degree of probability, as originating with a particular person or source.
Evidence with Individual Characteristics
What are the three types of unknown or questioned samples?
1) recovered crime scene sample whose source is in question
2) questioned evidence that may been transferred to an offender during the commission of a crime and been taken away by him or her.
3) evidence from an unknown or questioned source that can be used to link multiple offenses
What are the three types of known samples?
1) standard or reference sample
2) control or blank sample
3) elimination sample
This type of sample is taken from a source known to have had lawful access to the crime scene (such as a police officer, medical technician, or occupant):
Elimination Sample
By comparing these three characteristics soil examination can determine whether soils share a common origin.
1) Color
2) Texture
3) Composition
Footwear prints are formed when the soles of footwear, soles of feet, and tires are contaminated with foreign matter such as blood or dust and leave a print on a firm base, such as a floor, a chair, paper, or cloth. Such prints are called:
Residue Prints
These are several methods by which footwear prints can be recovered. The best approach is to:
Send the original evidence to the lab
DENTAL STONE or die stone-for example, Traxtone-is the most used casting medium because of its:
1) Greater strength
2) Quicker setting time
3) and ease of use,
4) cleaning casts made doesn’t result in any loss of detail,
5) provide more detailed impressions
The first step in casting is:
The preparation of the impression
Dental stone sets fairly rapidly. Die stone sets up quicker, in how many minutes:
12 to 15 minutes
If there is standing water in the impression, the following steps should be taken:
1) place a casting frame around the impression so that a cast 2 inches deep can be made;
2) gently sift dental stone that has not been mixed with water directly into the impression to a depth of about 1 inch
3) add enough dental stone to form a second 1-inch layer, and
4) allow the cast to set in place for at least one hour
Paint is transferred as fresh smears, dried chips, or chalking from old, dry paint. Cases in which such transfers commonly occur include:
1) Burglaries
2) Hit and Run Accidents
Laboratory examination of glass evidence may be able to determine:
1) The type of glass, such as tempered or container
2) The direction of force used to break the glass
3) The direction and sequence of shots fired through closed glass window
4) Similarity between evidence glass and standards
5) A fracture physical match, establishing that the pieces were formally joined
Glass is important as physically evidence because:
It is so common
Fibers are of greater value as evidence than are rootless hairs because they incorporate such variables as: (8)
1) material type
2) number of fibers per strand
3) number of strand
4) thickness of fibers and strand
5) amount and direction of twists
6) dye content
7) type of weave
8) the possible presence of foreign matter embedded in them
Both fibers and cloth fragments should be packaged in a ____________
or in ______________that is taped shut?
Pillbox or in folded paper
String cord, tape and rope evidence is usually found in:
1) robbery
2) murder
3) rape
4) kidnapping
Less frequently it is found in:
1) Accidental hangings by children
2) Accidental sexual asphyxiations
A fingerprint is a replica of the friction ridges that touched the surface on which the print was found. These ridge characteristics are also called:
Minutiae
There are three broad categories of latent fingerprints: (3)
1) Plastic prints
2) Patent/contaminated/visible prints
3) Latent/invisible prints
PLASTIC PRINTS are created when fingers touch material such as:
1) Painted surface that’s still”tacky”
2) Oil films
3) Explosives
4) Edible fats
5) Putty
6) Dust
7) Caulking, and
8) Similar surfaces
These prints result after fingers, contaminate with foreign matter such as soot, oils, face powder, ink, and some types of safe insulation, touch a clean surface.
Patent/Contaminated/Visible Prints
The most common type of contaminated print results when a finger is pressed into a:
Thin layer of dust before touching a smooth surface
These prints are associated with the small amounts of body perspiration and oil that area normally found on the friction ridges.
Latent/Invisible Prints
The quality of latent fingerprints is affected by a number of conditions, including the following:(5)
1) the surface on which the print is deposited
2) the nature of the material contaminating the fingerprint
3) any physical or occupational defects of the person making the print
4) how the object on which the print appear was handled
5) the amount of contamination
These prints may require little of development (2)
Plastic and Contaminated
There are numerous ways to develop latent prints. Four methods that investigators should be familiar with are:(4)
1) use of traditional powders
2) use of fluorescent powders
3) application of chemicals
4) cyanoacrylate or superglue fuming
The most common method of development latent/invisible prints is through the use of:
Traditional Powders
Commercially prepared traditional powders come in a number of colors, including:(5)
1) black
2) white
3) silver
4) red
5) gray
The choices of brushes include:(3)
1) Fiberglass
2) Feathers, and
3) Camel Hair
This is a dye sensitive to properties in blood and may be used with contaminated/visible prints involving blood.
Amido Black
This is used to develop purplish latent prints on the adhesive side of almost any kind of tape.
Gentian Violet
This chemical is used to develop latent prints on paper and cardboard, producing purplish prints.
Ninhydrin
This chemical is about three times more sensitive in developing latent prints on paper. The developed red-colored prints are immediately visible but paler than those produced by ninhydrin.
DFO
This is used for developing latent prints that have been immersed in water?
Small-particle reagent (SPR)
This is an excellent fluorescent chemical dye to use on metal, glass, leather, plastic, wood, and many other types of non absorbent surfaces:
Rhodamine 6G
After superglue fuming, this can be effectively used on no porous surfaces:
Basic Yellow 40
Superglue fuming was developed in 1978 and its use quickly spread. The three factors associated with its rapid acceptance were:
1) ease of use
2) remarkable results
3) low cost
When latent print has been developed, lifted, and placed on a card, it is necessary that the card be properly identified. Information recorded on the card should include:(7)
1) the date
2) type of card
3) case number
4) address of the crime scene
5) name of the officer who made the lift
6) exact place of the lift
7) type of object from which the print was lifted
Key target areas for finding latent prints on the victim are:
1) Ankles
2) Armpits
3) Wrists
4) Inner Thighs
5) The Neck
