Fingerprints: Your Personal Signature

1. Fingerprints: Your Personal Signature

2. Fingerprint History • Pre-History-Early potters identify their works with an impressed fingerprint • 1000BC-Chinese sign legal documents using fingerprints • 1685-Marcello Malpighi first recognizes and describes fingerprint patterns. • 1823-JohannesPurkinjie establishes 9 basic fingerprint patterns and rules for classifying them. • 1858-Sir William Herschel first notes the individuality of handprints, and finds they remain unchanged after 50 years.

3. Fingerprint History Cont • 1892-Sir Francis Galton publishes the textbook Finger Prints in which he offers convincing evidence that no two prints identical. • 1899-Sir Edward Henry devises a classification system based on five types of prints. This system is the basis for ones used in the US and Britain today. • 1910-Thomas Jennings becomes the first person convicted in the US on fingerprint evidence.

4. Anthropometry: A Precursor to Fingerprinting • Anthropometry is the science of measuring humans. • First developed by Alphonse Bertillon, and became known as Bertillonage in the late 19th century. • System collected numerous body measurements and categorized various facial features of a person • According to Bertillionage measurements the odds of two people being the same where 286 million to one.

5. Difficulties with Bertillionage Measurements • A Bertillionage catalogue included: • Photographs of each person • A set of complex anthropometric measurements and feature classifications were collected on a card. • The complexity of the system made it difficult and it gave way to a new identification method—fingerprinting—in early 20th century

6. Anatomy of a Fingerprint • Finger pads-Fleshy service of the finger used for touching and gripping. • Grooves, and friction ridges arranged in patterns.

7. Ridgeology • Ridgeology: The study of the uniqueness of friction ridge structures and their use for personal identification. • The uniqueness of a fingerprint can be determined by the pattern of ridges and valleys as well as the location, shape, and position of minutiae points. • Minutiae are points where ridge structure changes

8. Basic and composite ridge characteristics (minutiae) Example Minutiae Example Minutiae Trifurcation Short Ridge Bifurcation Hook Bridge Opposed Bifurcation Opposed Bifurcation/ Ridge Ending Dot Double Bifurcation Ridge Crossing Ridge Ending Enclosure (Lake)

9. Classifying Prints • Patterns: • Arches • Ridgelines that rise in the center to create a wavelike pattern. Subgrouped into plain or tented. Only 5% of all pattern types are arches. Plain Tented

10. Classifying Prints Cont • Loops-comprised of one or more ridges that double back on themselves. About 60% of patterns in human fingerprints are loops. • Radial loops flow downward toward the radius (thumb side)

11. Classifying Prints Cont • Ulnar loops flow downward toward the ulna (little finger) side.

12. Classifying Prints Cont • Whorls-Look like little whirlpools of ridgelines. They are characterized by 2 or more deltas. Whorls make up 35% of patterns in human fingerprints. • Plain Whorls-are either concentric circles or spiral Delta Delta

13. Classifying Prints Cont • Central pocket loop whorls-resemble a loop with a whorl at its end.

14. Classifying Prints Cont • Double loop whorls-Include two loops that collide to produce an S-shaped pattern

15. Classifying Prints Cont • Accidental loop whorls-Slightly different from other whorls and are irregular.

16. Quick Tips • If a fingerprint has no deltas, it is an arch. • If a fingerprint has one delta, it is a loop. • If a fingerprint has two or more deltas, it is a whorl.

18. The Henry Classification System • Developed by Sir Edward Henry in the late 1800s for criminal investigations in British India. • Was the basis of modern day AFIS classification methods up until the1990s. • Using the Henry system, individual prints are assigned scores based on where a whorl shows up within a 10 finger set of prints.

19. The Henry Classification System Cont.

20. The Henry Classification System Cont. • The fingerprint record’s primary grouping is determined by calculating the ratio of one plus the sum of the values of the whorl-patterned, even-numbered fingers; divided by one plus the sum of the values of the whorl-patterned, odd-numbered fingers • 1+((Sum whorled, Even finger value) (Sum whorled, Odd finger value)) =Primary Grouping Ratio

21. The Henry Classification System Problems • This system separates fingerprint files into 1,024 groups. • Investigators then had to analyze the minutiae by hand in order to match the prints. • Analyzing and matching a set of prints could take months • Criminals did not always leave behind a full set of 10 prints.

22. AFIS technology (Automated Fingerprint Identification System) • Collaboration between the FBI and the National Institute of Standards and Technology(NIST) in the 1960’s • The Henry Classification System has been a highly influential force in the formation of current AFIS technology. • Primarily envisioned used as a tool to expedite the manual searching of fingerprint records, eventually reducing matching time requirements from months to hours.

23. AFIS Technology Cont. • Up until the mid 1990s, it was not unusual for a state or city to continue to maintain its physical file of Henry-sorted fingerprint cards just in case a disaster occurred in the AFIS. • AFIS began to classify fingerprints according to the distance between the core and delta, minutiae locations, and pattern type.

24. Interesting Facts • Did you know? • Police investigators are experts in collecting “dactylograms”, otherwise known as fingerprints. • The koala is one of the few mammals (other than primates) that has fingerprints. In fact, koala fingerprints are remarkably similar to human fingerprints; even with an electron microscope, it can be quite difficult to distinguish between the two.