Unit 6: Fingerprinting Flashcards
What is the study of fingerprinting for identification purposes called?
Dactylography or dactyloscopy
Which parts of your body have fingerprints?
Fingers, toes, feet, palms, and lips
What are the raised portions of the skin called?
Dermal or friction ridges
What do ridges help one with?
Help us to grip objects also have the most nerve endings
How does a ridge appear on a fingerprint?
It appears dark and a valley appears light
When do fingerprints begin to form?
Around 10 weeks of pregnancy, when the fetus is 3 inches long (in a fetus, the basal layer cells grow faster than the other layers above and below it, so it collapses and folds to form shapes)
What makeup the 3 layers of skin:
- Inner layer: dermis
- Outer layer: epidermis
- Layer in between: basal layer
Where does fingerprint residue originate from?
From the glands in the subcutaneous skin
What are the two glands responsible for the fingerprint residue also known as the sweat glands?
Apocrine and eccrine glands
What are apocrine glands associated with?
Hair follicles (like top of alphabet on head)
What are eccrine glands located?
Ridges of the hand and feet
What are the two things that a forensic examiner looks for?
- Core (center of a loop or whorl)
- Deltas (a triangular region located near a loop)
What are the three types of fingerprint patterns?
- Loop
- Whorl
- Arch
What are the types of arches?
- Plain arch: ridges enter one side and exit on the other
- Tented arch: has a spike in the center
Types of loops?
These patterns are named for their positions related to the radius and ulna bones:
- Radial loop (right thumb): loop opens towards the left or the radial bone (on left-hand side)
- Ulnar loop (right thumb): loop opens towards right of the ulna bone opens towards ulna bone
Types of whorls?
- Plain whorl (one or more ridges that make a complete circuit, with 2 deltas)
- Central pocket whorl (one recurring edge, or obstruction at a right angle to the line of flow)
- Double loop whorl (made up of any 2 loops combined)
- One print (like yin-yang)
- Accidental (does not clearly fall into any other categories)
Does every person, including twins have individual fingerprints?
Every individual has a unique fingerprint resulting from unique ridge patterns called minutiae (called this because the details are so minute or small)
What are minutiae?
They are points where print ridges come together or end; they are considered to be the uniqueness of an individual.
What is the twelve-match guideline?
When a fingerprint expert takes the witness stand and says he is absolutely certain two fingerprints match, he means that he has found at least twelve or more matching minutiae
How many minutiae until it is considered to be individual?
8 (no more than 8 common minutiae)
What are the different types of minutiae patterns?
- Ending ridge (just ends)
- Bifurcation (looks like a fork)
- Island ridge
- Dot
- Bridge
- Spur (hook)
- Eye (island)
- Double bifurcation
- Deltas
- Trifurcation
How to take a ridge count?
Draw an imaginary line from the center of the core to the edge of the delta, and intersecting ridges are counted (do not include ridge of core or delta only in between)
What are the 3 types of fingerprints?
- Patent fingerprints
- Plastic fingerprints
- Latent fingerprints
What are patent fingerprints?
Or visible prints are left on a smooth surface when blood, ink, paint, grease, or some other liquid comes into contact with the hands and is then transferred to that surface
What are plastic fingerprints?
Are actual indentations left in some soft material such as clay, putty or wax
What are latent fingerprints?
Are caused by the transfer of oils and other bodily secretions onto a surface (hard to see, not visible to the naked eye)
How are latent fingerprints made visible?
Using chemicals
How do you dust for fingerprints?
Using a fine carbon powder to make it more visible (metal or magnetic powders can be used), and tape can be used to preserve the fingerprint
What makes fingerprints stand out on paper?
Ninhydrin; bonds with the amino acids in fingerprints and will produce a blue or purple colour; it is used to lift prints from surfaces such as paper and cardboard
What makes fingerprints more visible on any object?
Cyanoacrylate; this method (often called the super glue method) is a procedure used to develop latent fingerprints on many objects and turns them white (because the glue dries white); basically taking glue heating it into vapour and they adhere to print
What makes latent prints appear on wood or styrofoam?
Silver nitrate; chloride from salt in sweat on the print combines with silver nitrate to form silver chloride; this makes the print come out black or red under UV light
What makes latent prints appear on paper, cardboard, or other unpainted surfaces?
Iodine fuming; iodine combines with carbohydrates in latent print, and it turns print brown (fades quickly so must be photographed immediately)
How does one preserve fingerprint evidence?
- Wear gloves at all times
- Touch as little as possible and then only in areas least likely to contain identifiable latent prints, such as rough surfaces
- Precaution should be taken when marking evidence so as not to destroy potential latent prints
- Papers and documents containing latent prints should be placed individually in a cellophane or manila envelope. Such a container can be sandwiched between two sheets of stiff cardboard, wrapped and placed in a box for mailing
Is it possible for the same two people to have the same fingerprint…?
No, a fingerprint is an individual characteristic. No two people have identical ridge patterns, a fingerprint remains unchanged for a persons lifetime
It is possible for a print to change during a person’s lifetime?
No, but it may change due to scars or skin diseases…what criminals don’t realize is that scars on fingers make them more unique and when acid is used the prints grow back
Who developed the classification system for fingerprints?
Sir Francis Galton and E.R Henry
What is the system that provides digital, automated fingerprint searches…
Integrated Automatic Fingerprint Identification System (AFIS); contains over 50+ million fingerprint records
How does AFIS work?
An unknown print is scanned and entered into the computer. The computer searches the AFIS system and produces a list of file prints that match closest with the search print; this takes about 2 hours. A fingerprint expert then examines prints and makes final verification of the print’s identity
Is IAFIS just for criminal checks?
No; it also collects fingerprints for employment, licenses, and social services programs (such as homeless shelters).
What is the IRIS identification system?
It is a scanning of the iris in the eye to identify people
Is AFIS used in Canada too?
Yes, takes finger and palm prints of charged
Who was the first policing system to use fingerprint identification?
The Toronto Police Service
What is Interpol?
It is the International law enforcement agency, also called AFIS, and authorized users from other countries can cross-check records from their national fingerprint databases when they think there may be an international aspect to the crime
Who was a criminal who was convicted using fingerprint evidence?
Richard Ramirez (the Nightstalker), trained by his cousin to stalk and prey on individuals just murdered them
