Forensics: Fingerprints Quiz Flashcards
What are fingerprints?
A fingerprint is an impression left on any surface that consists of patterns made by the ridges on a finger.
What are fingerprints a result of?
Fingerprints are a result of oil and secretions from skin mixing with dirt.
When and where do ridges form on the skin?
Fingerprints form at the beginning of the 10th week of pregnancy (in the womb) in the epidermis, the outermost layer of skin.
Why do ridges form on the skin?
From the pressure of the amniotic fluid on the epidermal layer
When you touch something, what are you leaving on the surface?
The residue on our friction ridges
Define a patent print.
Visible prints left on a smooth surface when blood, ink, or some other liquid comes in contact with the hands and is then transferred to that surface.
Provide an example of a patent print.
Blood, oil, ink
Define a latent print.
Hidden prints caused by the transfer of oils and other body secretions onto a surface; made visible by dusting with powders or some chemical reaction.
Define a plastic print.
Actual indentations left in some soft material such as clay, putty, or wax.
Provide an example of a plastic print.
Putty, butter
What is the most common fingerprint pattern?
Ulnar loop
What is the least common fingerprint pattern?
Arches
What are the two types of loops?
Radial Loop (going towards thumb)
Ulnar Loop (going towards pinky)
What are the two types of arches?
Plain Arch and Tented Arch
What are the three types of whorls?
Plain whorl
Central Pocket Loop Whorl
Double Loop (Whorl)
What are the seven types of minutia?
Ridge ending
Bifurcation
Lake/Enclosure
Spur
Bridge/Crossover
Dot/Island
Independent Ridge
How do you dust prints?
- Gently spin brush to separate the bristles
- Lightly dab bristles into powder
- Twirl brush to remove excess powder
- Twirl brush between index finger and thumb while lightly brushing the bristles across the surface
- If ridge detail appears, continue to twirl the brush in the direction of the ridge flow until you develop completely
Why do dusting and lifting prints work?
Because the dust sticks to the non-oil porous
What won’t latent prints tell you?
How old a latent print is, the age of the person, gender, ethnicity, etc.
What are deltas?
Triangular region where ridges diverge
How many deltas are in Loop prints?
1
How many deltas are in Plain Whorl prints?
2
How many deltas are in Plain Arch prints?
0
How many deltas are in Double Loop Whorl prints?
2
What makes a fingerprint individualizing?
The pattern of the print along with the location of the minutia
Why do we have friction ridges?
They help us hold things.
Help protect our skin.
What is AFIS?
Automated Fingerprint Identification System
