Friction ridges
Raised ridges on the palms, soles, ends of fingers and ends of toes, of all primates which are part of a complex manipulation and sensory system.
They begin forming in the 9th or 10th week of foetal development, first the primary ridges deep in the dermal
Patent prints
Prints visible to the unaided eye. Occur due to a transferrable material on ridge pattern, such as paint or blood.
Latent prints
Prints that require some form of assistance to make them visible. Composed of sweat and oil from the body transferred on the ridges to some substrate.
Fingerprint powder
Visualising technique where coloured, fluorescent or magnetic materials are finely ground and brushed lightly over a suspected print, producing a contrast between the background and the print. They are applied with a soft fibreglass brush with long fine b
Visualisation methods
Gentian Violet
Iodine Fuming
Ninhydrin
Physical developer
Cyanoacrylate (super glue) fuming
Vacuum Metal deposition
Small Particle Reagent
Sudan Black
Minutiae
Various ridge characteristics.
The presence, kind, number and arrangement of these characteristics that create a unique pattern.
Partial print
Print that shows only a portion of the complete print pattern.
Fingerprint classes
Loops
Arches
Whorls
Loops
Most common fingerprint pattern with about 60-65% appearance.
One or more ridge entering from one side of the print and curving back on themselves and exiting the fingertip on the same side.
Ulnar loop
Where the loop of a fingerprint enters and exits on the side of the finger toward the little finger.
Radial loop
Where the loop of a fingerprint enters and exits on the side of the finger toward the thumb.
Type lines
The two diverging ridges that surround all loops.
Delta
The point of divergence alongside a loop.
Core
The central portion of the loop.
Arches
The rarest of all fingerprint patterns at approx. 5%.
Ridges enter from one side of the finger, gradually rise and then exit the other side of the finger.
Arches have no type lines, cores or deltas.
Plain arch
Rounded peak
Tented arch
Pronounced sharp peak, or any pattern that resembles a loop but lacks one of the required traits.
Whorls
Make up approx. 30-35% of prints. Fingerprint patterns that resemble small whirlpools revolving around a point. All have type lines and at least two deltas.
Plain whorl
Type of whorl that has a minimum of one ridge that is continuous around the pattern, but is not necessarily circular (can be oval, ellipse or a spiral).
Located between the two deltas. Line drawn between two deltas will touch the circular core.
Central pocket loop
Type of whorl that has a minimum of one ridge that is continuous around the pattern, but is not necessarily circular (can be oval, ellipse or a spiral).
Not located between the two deltas.
Double loop
A type of whorl with two loops that swirl around one another.
Accidental
A type of whorl pattern that combines two or more patterns (excluding plain arch) and does not clearly meet the criteria for any other pattern.
Primary classification
A modern fingerprint classification that encodes fingerprint pattern information into two numbers derived as follows.
All arches and loops are considered non-numerical patterns and are given a value of zero. Whorls are given values based on which finger t
Whorl primary classification values
Right thumb or index finger = 16
Right middle or ring finger = 8
Right little finger or left thumb = 4
Left index or left middle finger = 2
Left ring or left little finger = 1
AFIS
Automated fingerprint identification systems.
Databases of digital fingerprints.
Level 1 detail
General ridge flow and pattern configuration. Does not individualise but may help to exclude.
May include info on orientation, delta and core location and distinction of finger vs. palm.
Level 2 detail
Formations - Ridge endings, bifurcations, dots or combinations of these features.
Enables individualisation using the relationship of the features across the print. This defines the uniqueness of the print.
Level 3 detail
All attributes of a ridge.
Includes ridge path deviation, width, shape, pores, edge contour, incipient ridges, breaks, creases, scars and other permanent minutae.
Individualising.
Minutiae
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Optical coherence tomography
An emerging technology for performing high-resolution cross-sectional imaging. OCT is analogous to ultrasound imaging, except that it uses light instead of sound.
Allows for separation of layered images.
Age of fingerprints
Plastic prints remain as long as the impressed material is structurally intact
Prints left in a medium, such as blood or dust, are fragile and do not last long
Latent prints, in a proper environment, can last for years
Age of prints is almost impossible t