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Terms in this set (21)
What are fingerprints?
Small ridges that are raised portions of the skin, arranged in connected units called dermal, or friction, ridges. When these ridges press against things, they leave a mark or impression called a fingerprint
When are fingerprints formed?
Near the 10th week of pregnancy, when the fetus is about 3 inches long
What are the 3 layers of skin? Explain how their growth impacts fingerprint development.
Outer layer- epidermis
Layer below the epidermis- dermis
Inner-most layer- hypodermis
Which sweat glands are located on the hands and feet?
What do we call the study of fingerprints for identification purposes?
Dactylography or Dactyloscopy
What are the fundamental principles of fingerprints?
A) A fingerprint is an individual characteristic; no two people have identical ridge patterns
B) A fingerprint remains unchanged during a person's lifetime
C) Fingerprints have general ridge patterns that allow them to be systematically identified
Why do we no longer use the Bertillon systems?
It was proven unreliable when two people had the same name and same body measurements- fingerprints have been proven to be individualized
What fingerprint classification system is still used today in the U.S?
The Henry System
What are the 3 major classes of fingerprints? Describe each and give their % occurrence.
How many ridge characteristics are in the average fingerprint?
Explain why criminals are unsuccessful at altering their fingerprints?
A fingerprint remains unchanged - fingerprints dissolved by acid will grow back. Scars on fingers will make prints even more unique.
What are the different types of fingerprints?
Visible Prints- When blood, ink, paint, grease, or some other liquid comes in contact with the hands and is then transferred to a surface
Plastic Prints- Indentations left in some soft material such as clay, putty, or wax
Latent Prints- Not visible to the naked eye but can be made visible by using chemicals
What is AFIS and what does the acronym stand for?
Automated Fingerprint Identification System- provides digital, automated fingerprint searches, latent searches, electronic storage of fingerprint photo files, and the electronic exchange of fingerprints and test results
Ninhydrin- Uses, Application, Reacts with, Appearance of Latent Print
Application: Object dipped or sprayed in ninhydrin; wait 24 hours
Reacts with: Amino acids in sweat
Cyanoacrylate Vapor- Uses, Application, Reacts with, Appearance of Latent Print
Uses: Household items: plastic, metal, glass, and skin
Application: Heat sample in a vapor tent
Reacts with: Amino acids
Silver Nitrate- Uses, Application, Reacts with, Appearance of Latent Print
Uses: Wood, styrofoam
Application: Object dipped or sprayed in silver nitrate
Reacts with: Chloride from salt in sweat on the print combined with silver nitrate to form silver chloride
Appearance: Black or red- Brown under UV light
Iodine Fuming- Uses, Application, Reacts with, Appearance of Latent Print
Uses: Paper, cardboard, unpointed surfaces
Application: In a vapor tent, heat solid iodine crystals
Reacts with: Iodine combines with carbohydrates in latent print
Appearance: Brown (fades quickly- must be photographed)
Which type of fingerprint is the primary classification system based off of?
P.C = sum of even finger whorl values +1 /
sum of odd finger whorl values +1
( 16, 16, 8, 8, 4, 4, 2, 2)
Determine Ridge Count
An imaginary line is drawn from the center of the core to the edge of the delta and intersecting ridges are counted
*Be able to classify fingerprints and identify ridge characteristics
Ending ridge, Bifurcation, Island Ridge, Dot, Bridge, Spur, Eye, Double Bifurcation, Delta, Trifurcation
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