1. Chapter 14 Criminalistics
Fingerprints
Chapter 14
Criminalistics

2. History of Fingerprinting
First systematic attempt at personal identification
Alphonse Bertillon in 1883
Anthropometry: system of precise body measurements
Included detailed descriptions of the subject
Full-length and profile photographs
Accuracy of measurements were disproved by the William West Case

3. History of Fingerprinting
Francis Galton
1892: Published Finger Prints
Described the anatomy of fingerprints and suggested methods for recording them
Acknowledged that no two prints are alike and do not change throughout a lifetime
Three pattern types
Loops, Arches, and Whorls

4. Fundamental Principles of Fingerprints
First Principle
A fingerprint is an individual characteristic. No two fingers have yet been found to possess identical ridge characteristics
Individuality of a fingerprint is not determined by its general shape or pattern but by careful study of ridge characteristics or minutiae
Examples: bifurcation, enclosures, islands, ridge endings, short ridges, ridge crossings, deltas

5. Figure 14-1

6. Figure 14-2

7. Fundamental Principles of Fingerprints
Second Principle
Fingerprints have been designed by nature to increase grasp and to resist slippage and are formed in the fetal stage of development.
Fingerprints are formed by:
Hills (Ridges): raised portions of the epidermis
Valleys (Grooves): lowered portions of the epidermis
IT IS THE RIDGES THAT ARE INKED WHEN FINGERPRINTS ARE TAKEN

8. How are Fingerprints Formed?
The Dermal Papillae is the boundary between the epidermis (outer skin) and the dermis (inner skin).
The shape of this boundary is wavy. This wave pattern determines the pattern of the fingerprint and remains unchanged throughout your lifetime.

9. Leaving Your Mark
Skin ridges have a single row of pores that open from the sweat glands.
Perspiration is discharged through the pores and oils from the body collect in the ridges and valleys.
Impressions from the fingertips are transferred onto a surface, leaving a fingerprint.
Latent fingerprints are deposited in this manner and cannot be seen with the naked eye.

10. Fundamental Principles of Fingerprints
Third Principle
Fingerprints have general ridge patterns that permit them to systematically classified.

11. Taking Fingerprints
Fingers are rolled in ink left-to-right, careful not to adhere too much ink to the fingertips
The fingertips are then rolled left-to-right on a Ten-Print Card in the appropriate place for each finger
A straight down print is then taken for each of the four fingers simultaneously and for each thumb and recorded on the Ten-Print Card

13. This is the original Ten-Print Card of Rosa Parks after the Montgomery Bus Boycott

14. Three Classes of Fingerprints
Loops, Whorls, and Arches
Loops: 65% of world’s population
Whorls: % of world’s population
Arches: 5% of world’s population

15. Loop Patterns
One or more ridges entering from one side of the print, recurving, and exiting from the same side

16. Types of Loop Patterns Ulnar Loop: loop opens toward little finger
Radial Loop: loop opens toward the thumb
Type Lines: pattern area of the loop surrounded by two diverging ridges
Delta: the point directly in front of the diverging ridges—loops MUST have at least one delta
Core: the center of pattern

17. Types of Whorl Patterns
Four types of patterns
Plain Whorl
Central Pocket Loop Whorl
Double Loop Whorl
Accidental Whorl
All whorl patterns must have type lines and a MINIMUM of two deltas.

18. Types of Whorl Patterns
Plain and Central Pocket Loops
Plain whorl and central pocket loops have AT LEAST one ridge that makes a complete circuit
Ridge may be a spiral, oval, or any variant of a circle

19. Types of Whorl Patterns
Plain Whorl: an imaginary line is drawn between TWO deltas and the spiral is crossed
Central Pocket Loop: spiral is not crossed when imaginary line is drawn

20. Types of Whorl Patterns
Double Loop: has two loops in one fingerprint
Accidental Loop: has two or more patterns or is not classified into any other category

21. Types of Whorl Patterns
Figure 14-6

22. Arch Patterns
Plain arch: ridges entering one side of the fingerprint and exiting the other side
Tented arch: this pattern rises sharply in the center

23. Arch Patterns
Figure 14-7

24. Classification of Fingerprints
Original System: Henry System
Developed by Scotland Yard in 1901
Converted ridge patterns on all 10 fingers into a series of letters and numbers arranged into a fraction
Problem: could only classify fingerprints up to 100,000 files
Evolved into the FBI System of Fingerprint Classification

25. FBI System Primary System of Classification based on the Henry System
All fingerprints in the world can be classified into 1,024 groups

26. How the FBI System Works
Fingers are given numbers based on whorl patterns being present on each finger
R. Index R. Ring L. Thumb L. Middle L. Little
R. Thumb R. Middle R. Little L. Index L. Ring
Whorl Values
Zeros are assigned for loops and arches
Fraction gives individualized result for each person + + + + +

27. Problems with FBI System
25% of population falls into the 1/1 category
Only useful when all 10 prints are available
Cumbersome and Time Consuming to look through cards
Often only one or two prints found at a crime scene

28. AFIS Automated Fingerprint Identification System
Computer-scans and digitally encodes fingerprints based on minutiae of ridge endings and bifurications
List of prints is generated then a fingerprint examiner confirms match

29. Benefits of AFIS
Computer can make thousands of accurate fingerprint comparisons in a second
Can filter out imperfections in latent prints found at a crime scene
Suspect lists are generated faster and investigators can spend more time focusing on suspects

30. A Typical AFIS Matching Screen
                                     
A Typical AFIS Matching Screen

31. Types of Crime Scene Prints
Three Types:
Visible Prints
Plastic Prints
Latent (Invisible) Prints

32. Visible Prints Can be seen with the naked eye
Made by fingers touching a surface after ridges have been in contact with a colored material such as blood, paint, grease, ink, etc.

33. Plastic Prints Can be seen with the naked eye
Made by ridge impressions left on a soft material such as putty, wax, soap, dust, wet paint surfaces, etc.

34. Latent Prints Cannot be seen with the naked eye
Made by impressions caused by transfer of body perspiration or oils present on finger ridges to the surface of an object

35. Detection of Prints
Latent prints must be developed (found) through different methods
The method used is dependent on the surface being examined

36. Surface Conditions
Hard, nonabsorbent surfaces (glass, mirrors, tile, painted wood): Powders or SuperGlue Fuming
Absorbent surfaces (paper, cardboard, cloth): One or more specific chemicals

37. Fingerprint Powders Non-absorbent surfaces only
Applied with a camel’s hair or fiberglass brush
Color of powder chosen contrasts with surface color
Powder adheres to oils and perspiration left by ridges
Print can be lifted off the surface and preserved

39. Iodine Fuming Oldest chemical method for developing latent prints
Iodine is a solid crystal that, when heated, is transformed into a gas through sublimation
Material is placed in a chamber and iodine is heated and latent prints are revealed
Iodine prints are not permanent and must be photographed immediately or fixed with starch solution, which can last about 1 month

41. Ninhydrin
Chemical used to develop prints on porous material by reacting with amino acids in perspiration
Developed prints appear purple-blue in color
Prints appear within an hour or two and fully developed in hours
Commonly used on paper products

42. Latent Prints recovered on paper with Ninhydrin

43. Physical Developer Silver-nitrate based chemical
Useful for detecting prints that cannot be found by other methods or on objects that have been wet at one time
Application of Physical Developer washes away any protein that may be present and MUST be used last

44. SuperGlue Fuming
Used on nonporous surfaces such as metal, electrical tape, leather, and plastic bags
Active ingredient: cyanoacrylate ester
Evidence is placed in a fuming chamber and the cyanoacrylate is heated and covers the object and produces a white latent print

45. Flashlight battery exposed to SuperGlue Fuming

46. Laser Light
Perspiration contains a variety of components that fluoresce when illuminated by laser light
Because of the fluorescence, latent prints can be seen with the naked eye
Almost never used anymore with the invention of alternate light source latent print examination

47. Alternate Light Source
Works because perspiration fluoresces under different wavelengths of light
Can adjust the wavelength of light to be aimed through a fiber optic cable
More commercially available than laser light setups

48. Alternative Light Source being used to detect latent prints

49. Preservation of Prints
Common fingerprint methods do not interfere with further DNA analysis
However, when biological material remains, fingerprints should be developed at the crime lab instead of at a crime scene

50. Preservation of Prints
After prints have been found, photos must be taken
If object is small enough to be transported without destroying the print, it should be preserved intact
Cellophane should cover the print to protect from damage

51. Preservation of Prints
Prints on immovable objects should be lifted
Lifted prints should be preserved on a card that provides contrast