Fingerprints and Minutiae

Three fundamental principals of Fingerprints

• Individual characteristic• Will remain unchanged during the individual’s

lifetime• Have general characteristic ridge patterns that

permit systematic classification

History

• Alphonse Bertillon started the identification process with his Anthropometry measurements in 1881

• Francis Galton then upon studying fingerprints and Bertillon's method perfected the fingerprint system and published books in1892 and later Edward Henry simplified his system

• In 1901 Juan Vucetich set up a workable system refining Galton's system and it was used in Spanish speaking countries. He was the first to officially identify a criminal using the fingerprint system

3 TYPES OF FINGER PRINTS

• Latent – prints are not visible until developed made by oils and chemicals this type can be found on any evidence including skin.

• Visible –visible to naked eye—left by a finger that has touched material such as blood , paint etc.

• Plastic or Physical--- Made in soft material such as putty, paint, soap etc.

3 MAJOR PATTERNS OF FINGERPRINTS

• 3 main Patterns consisting of: • Arches – least common• Loops –most common-two sub groups …radial &

ulnar• Whorls- 4 sub groups--- plain whorl- central

pocket whorl- double loop whorl- accidental whorl

• Approximately five percent of all fingerprints are Arches, 30% are Whorls and 65% are Loops.

METHODS OF OBTAINING PRINTS• Some of the most common techniques of finding and lifting prints

include:• Dusting with carbon – dusting with white or black powder to

cover print( most common) can be used with glass, solids plastics etc.

• Super glue fuming – developed in 1970s--leaves white impression• Ninhydrin – reacts/amino acids in fingerprint and leaves purple

image used on matchbooks, newspaper etc.• Silver nitrate- reacts with NACL left from perspiration in the

fingerprint• Laser technology – laser images

INFO

• Fingerprints can last for years• Loop most common• Fingerprints composed of salt, oil, & amino

acids • Latent fingerprints can be left anywhere

including skin• Prints can also be found in feet and palms

even other parts of the body

Arch

Arch

• The Arch pattern has no delta or core; but, it too, must be fully recorded so that its individual characteristics can be readily distinguished.

• Simplest of all fingerprints

Tented arch

Whorl

Whorl

• A Whorl pattern will have two or more deltas. For a whorl pattern, all deltas and the areas between them must be recorded.

• Subdivided into 4 groups—plain whorl, central pocket loop whorl, double loop whorl, and accidental whorl

Loop

Loop

• In the Loop pattern there are two focal points:• the Core, or the center of the loop, and the delta. • The Delta is the area of the pattern where there is a

triangulation or a dividing of the ridges. • Most common type• When recording fingerprints, the delta and the area between

the delta and the core must be completely recorded• Two types of loop: Ulnar loop – opens toward the little finger

and the Radial loop – opens toward the thumb

Minutiae

•Different ridge characteristics in the finger prints

Ridge Ending

• Ridge ending

a single ridge ending within a friction ridge structure

Ridge characteristics/Bifurcation

• BifurcationThe point at which one friction ridge divides into two friction ridges

Enclosure or eye ridge

A single friction ridge that bifurcates and rejoins after a short course and continues as a single friction ridge

Island or short ridge

a single friction ridge that only travels a short distance before termination

Crossover ridge

One ridge crosses Over another ridge Will look like an x

Dot ridge

Small dot by itself in the middle of two or more ridges

Spur ridge

• The spur has a single short ridge that looks like a hook that comes off of a longer ridge.

•µ

Triple bifurcation ridge

• Similar to the bifurcation except it has three ridges coming of the main ridge looks sort of like a fork

Bridge

• Two ridge points are joined together by a short ridge

•

• ≠

Other Characteristics

Scaring…..

Points used for identification

• No legal requirements in the USA for the number of points that must match before deciding that a print matches

• Criminal courts will generally accept 8-12 points.

• Apx 150- 200 minutiae in properly rolled fingerprint.

Match the points

Are they fool proof?• Fingerprints cannot lie however analysis and identification are

subject to error.• Example: Madrid bombings on March 11, 2004 coordinated

train bombings in Madrid Spain killed 191 people ( 911 days after 9/11)

• Bag found with fingerprints identifying Brandon Mayfield, an Organ lawyer..he was held for two weeks while investigated and it turned out after a more thorough analysis the prints were not an exact match…..FBI acknowledged “serious error” in the identification and apologized. Mayfield was not satisfied and sued the U.S. gov and settled for 2 million dollars.

AFIS

• Automated Fingerprint Identification System• FBI system that stores all fingerprints taken –

over 200 million prints on file with FBI• Linked to countries around the world • Decreases the ability of criminals to flee the

country or to commit murders in several different places.