1. Chapter 14: FINGERPRINTS

2. FUNDAMENTALS OF FINGERPRINTS
FIRST PRINCIPLE:
Fingerprints are an Individual Characteristic. No two fingers have yet been found to possess identical ridge characteristics.

3. FUNDAMENTALS OF FINGERPRINTS
MINUTIAE
- Ridge Characteristics Define Individuality
Assess:
IDENTITY or Type of minutiae
NUMBER of minutiae
RELATIVE LOCATION of minutiae
COMPARE POINT BY POINT
POSSIBLY 150 POINTS ON THE AVERAGE FINGERPRINT

4. First Principle (cont) Ridge Characteristics

5. First Principle (cont)

6. FUNDAMENTALS OF FINGERPRINTS
MINUTIAE - Ridge Characteristics Define Individuality
HOW MANY POINTS
MAKE A MATCH?
Depends on experience and
knowledge of the examiner
Usually 8 to 16

7. First Principle (cont)
The GBI requires ridge characteristics for a match.
The FBI will often take 7-10 characteristics for a match.

8. FUNDAMENTALS OF FINGERPRINTS
SECOND PRINCIPLE:
A Fingerprint will remain
LARGELY UNCHANGED
during an
Individual’s Lifetime

9. Second Principle:

10. Second Principle (cont)
Though efforts have been made to obscure one’s fingerprints, it would be totally impossible to obliterate all the ridge characteristics on the hand, and the presence of permanent scars only provides new characteristics of identification.

11. Second Principle (cont)
John Dillinger, a
notorious gangster,
tried to destroy his
own fingerprints by
applying acid.

12. FUNDAMENTALS OF FINGERPRINTS
THIRD PRINCIPLE:
Fingerprints have general ridge patterns that permit them to be systematically classified. All fingerprints are divided into three classes on the basis of their general pattern:
Loops, Whorls, and Arches

13. Third Principle Terminology
Type Lines - two diverging ridges usually coming into and splitting around an obstruction (delta)
Delta – a triangular area where the ridges radiate outward in three directions.
Core – approximate center of the pattern
Core

14. What are the three ways to classify fingerprints?

15. FUNDAMENTALS OF FINGERPRINTS
ARCHES 5%
LOOPS 60% - 65%
WHORLS 30% - 35%

16. FUNDAMENTALS OF FINGERPRINTS
ARCHES - least common of three patterns
RIDGES ENTER ONE SIDE OF PATTERN AND EXIT ANOTHER
Arches do not have type lines, deltas, or cores.
2 Types
PLAIN ARCHES - wavelike pattern
TENTED ARCHES - sharp spike

17. Third Principle – Plain Arch
A plain arch is that type of pattern in which the ridges enter upon one side, make a rise or wave in the center and flow or tend to flow out upon the opposite side.

18. Third Principle – Tented Arch
A tented arch is that type of pattern which possesses either an angle, an upthrust, or two of the three basic characteristics of a loop.

19. FUNDAMENTALS OF FINGERPRINTS
LOOPS - most common type
Ridges enter one side and exit same side
ULNAR LOOP - opens toward little finger
RADIAL LOOP - opens toward thumb
Must identify on which hand the print is found

20. FUNDAMENTALS OF FINGERPRINTS
LOOPS -
CORE
TYPE LINES
DELTA

21. FUNDAMENTALS OF FINGERPRINTS
WHORLS –
FOUR types TYPES
Plain
Central pocket
Double loop
Accidental
ALL HAVE TYPE LINES, A CORE & and at least TWO DELTAS

22. Third Principle – Plain Whorl
Plain whorl consists of one or more ridges which make or tend to make a complete circuit, with two deltas, between which an imaginary line is drawn.

23. Third Principle - Central Pocket Whorl
Draw a line between the two deltas in the plain and central pocket whorls. If some of the curved ridges touch the line, it is a plain whorl. If none of the center core touches the line, it is a central pocket whorl.

24. Third Principle – Double Loop Whorl
Double loop whorl consists of two separate loop formations, with two separate and distinct sets of shoulders and two deltas.

25. Third Principle – Accidental Whorl
Accidental whorls consist of a combination of two different types of patterns with the exception of the plain arch, or a pattern which conforms to none of the definitions. Accidental whorls will have two or more deltas.

26. Classification
The original Henry system converted ridge patterns on all 10 fingers into a series of letters and numbers arranged in the form of a fraction.
The FBI needed to expand Henry’s classification capacity by modifying and adding additional extensions due to the increasing number of prints on file. This modification is known as the FBI system.

27. Classification (cont)
The Primary Classification is the first step in the FBI system. The steps for classification are:
Make a print of each finger
A value of zero is given to any print that is an arch or loop.
A number is given to any print that is a whorl, starting with 16 for the first pair, 8 for the second, 4, 2 and a value of 1 for the last pair.

28. Classification (cont)
The values are placed in a fraction sequence.
1/1 is added to the fraction total.
The final number is the primary classification number.

29. Primary Classification
The Henry—FBI Classification
Each finger is given a point value
right
left

30. Henry’s Finger Numbers and Finger Values
L Pinky L
Ring
L Middle
L Index
L Thumb
R Thumb
R Index
R Middle
R Ring
R Pinky
Finger Number 10 9 8 7 6 1 2 3 4 5
Value
(if Whorl) 16
Primary grouping determined by claculating 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 whorl-patterned, odd numbered fingers.
1 + (Sum of whorled, EVEN finger values) = Primary Grouping Ratio
1 + (Sum of whorled , ODD finger values)

31. Primary Classification
An example sequence:
= 9
About 25% of the population have a 1/1primary classification, meaning they have only arches or loops, or combination of both.
right
left

32. Fingerprint Comparison
Three types of fingerprint files are in use:
Manual System — An examiner thumbs through each fingerprint card on file and makes an identification with no predetermined minimum set of comparison points.
The Semi automated System — IBM punch cards are used and compared to similar cards, according to Henry’s system.
Fully Automated (AFIS) — a computerized system that houses a large data base of fingerprints of previously arrested persons.

33. Automated Fingerprint Identification System (AFIS)
uses automatic scanning devices that convert the image of a fingerprint into digital minutiae that contain data showing ridge endings and bifurcations.
When the scan is complete, the computer produces a list of file prints with the closest correlation to the search print.
The selected prints are examined by an expert; AFIS makes no final decision.