1. Chapter 4
Fingerprints
Kendall/Hunt

2. Fundamental Principles of Fingerprints
Chapter 4
Fundamental Principles of Fingerprints
A fingerprint is an individual characteristic.
A fingerprint remains unchanged during an individual’s lifetime.
Fingerprints have general characteristic ridge patterns that permit them to be systematically classified.
Even twins have different fingerprints
Kendall/Hunt Publishing Company
Kendall/Hunt

3. Skin
Fingerprints arise from the dermal papillae (layer of cells between epidermis and dermis)
Every person has different fingerprints (even twins)
Perspiration (from sweat glands), skin cells, proteins, fats/oils, and other materials are deposited when fingers touch a surface

4. Dactyloscopy: study of comparing fingerprint ridge structures.
Latent fingerprints: invisible fingerprints
Are made patent by adding powder, superglue fuming, or chemical reactions
Patent (Visible) Prints: fingerprints (from blood, ink, paint, oil, etc.)
Plastic (Impressed) Prints: fingerprints in a soft material such as putty, butter, clay, wax

5. Kendall/Hunt Publishing Company
Chapter 4
LOOP
WHORL
ARCH
Kendall/Hunt Publishing Company
Kendall/Hunt

6. 1. Loops: flow from one side of the finger, rise and then flow back to the same side of the finger
Ulnar Loop: (ridge starts on little finger side, extends across finger and curves back towards little finger side)
Radial Loop: (ridge starts on thumb side, extends across the finger and curves back to thumb side)
Double Loop: has two loops
Left Hand
Double Loop

7. 3. Whorls: circular ridges
2. Arches: ridges flowing from left to right with a rise or hill in the center.
Tented Arch: looks like it has a tent pole in the middle
3. Whorls: circular ridges

8. Central Pocket Loop Lateral Pocket Loop Composite Accidental
Other Types of Fingerprints
Central Pocket Loop
Lateral Pocket Loop
Composite
Accidental

9. What type of fingerprint are each of the following?
Chapter 4
What type of fingerprint are each of the following?
Kendall/Hunt Publishing Company
Kendall/Hunt

10. Fingerprint Minutiae Bifurcations: ridges that split into two ridges
Ridge ending: ridge that ends
Dot: tiny round ridges
Island: short ridge
Enclosure (eye): ridge that forks, and then comes back together
Trifurcation: ridge that splits into three ridges
Delta: triangle-like ridge
Bridge: ridge connecting two ridges
Spur: small ridge spurring off another ridge
Core: center of whorl

11. Kendall/Hunt Publishing Company
Chapter 4
Fingerprint Minutiae
Kendall/Hunt Publishing Company
Kendall/Hunt

12. Identify as many minutiae as possible on the following fingerprint:

13. Primary Classification
Chapter 4
Primary Classification
The Henry-FBI Classification System
Each finger is given a point value.
right
left
Kendall/Hunt Publishing Company
Kendall/Hunt

14. Primary Classification, continued
Chapter 4
Primary Classification, continued
Assign the number of points for each finger that has a whorl and substitute into the equation:
right right left left left
index ring thumb middle little + 1 =
right right right left left
thumb middle little index ring + 1
That number is your primary classification number.
Kendall/Hunt Publishing Company
Kendall/Hunt

15. Kendall/Hunt Publishing Company
Chapter 4
Comparison
There are no legal requirements in the United States on the number of points required for a match. Generally, criminal courts will accept 8 to 12 points of similarity.
Kendall/Hunt Publishing Company
Kendall/Hunt

16. Developing Latent Prints
Chapter 4
Developing Latent Prints
Developing a print requires substances that interact with secretions, causing the print to stand out against its background.
Powders—adhere to both water and fatty deposits. Choose a color
to contrast with the background.
Iodine—fumes react with oils and fats to produce a
temporary yellow-brown color.
Ninhydrin—reacts with amino acids to produce a purple color.
Silver nitrate—reacts with chloride to form silver chloride, a material that turns gray when exposed to UV light.
Cyanoacrylate—“superglue” fumes react with water and other fingerprint constituents to form a hard, whitish deposit.
Kendall/Hunt Publishing Company
Kendall/Hunt

17. Kendall/Hunt Publishing Company
Chapter 4
Other Prints
Lips—several common patterns
Voice—electronic pulses measured on a spectrograph
Foot—size of foot and toes; friction ridges on the foot
Shoes—can be compared and identified by type of shoe, brand, size, year of purchase, and wear pattern
Palm—friction ridges can be identified and may be used against suspects
Footprints are taken at birth as a means of identification of infants.
Kendall/Hunt Publishing Company
Kendall/Hunt

18. Other Prints, continued
Chapter 4
Other Prints, continued
Earprint catches murderer
A man has been convicted of suffocating an eldery woman on the basis of earprint evidence. The assailant was caught after police matched the inprint of his ear on the victim’s window. Police believe that the thief put his ear to the window to listen for signs of anyone home.
The blood vessel patterns in the eye may be unique to individuals. They are used today for various security purposes.
Kendall/Hunt Publishing Company
Kendall/Hunt

19. Kendall/Hunt Publishing Company
Chapter 4
AFIS
The Automated Fingerprint Identification System—a computer system for storing and retrieving fingerprints
Established in the 1970s, AFIS enables law enforcement officials to:
Search large files for a set of prints taken from an individual
Compare a single print, usually a latent print developed from
a crime scene
By the 1990s, most large jurisdictions had their own system in place. The problem: A person’s fingerprints may be in one AFIS database but not in others.
IAFIS—the FBI’s Integrated Automated Fingerprint Identification System, which is a national database of all 10-print cards from all over the country
Kendall/Hunt Publishing Company
Kendall/Hunt

20. Visualization of Fingerprints: Powders
Powders make latent prints visible: used on hard/ non-absorbant surfaces such as glass, mirror, tile, painted wood)
Black powders are used on light-colored backgrounds and silver/white powders are used on dark-colored backgrounds.
Before applying powder to brush, gently spin the brush between index finger and thumb to separate bristles.
Place a small amount of powder on the brush and gently
twirl to remove excess powder.
Twirl the brush while very lightly brushing the bristles across the surface of the fingerprint. If ridge detail appears, brush very lightly in the direction of the ridge flow.
If less contrast is seen, stop because the print is being brushed away.
Flourescence: Some powders fluoresce under UV light

21. Lifting Fingerprints
Hold a piece of clear tape (slightly larger than fingerprint) in both hands.
Attach the end of the tape in the right hand to the surface slightly to the right of the print.
Using the right thumb, smooth the rest of the tape onto the surface, working from right to left and then from center outwards.
Lift the tape and apply it to a piece of paper (from right to left)
Record date, time, name, location, and any other information about the print.

22. Fingerprint Scavenger Hunt
1. Find people with the 12 different fingerprint types:
Arch
Tented arch
Ulnar loop (right hand)
Radial loop (right hand)
Ulnar loop (left hand)
Radial loop (left hand)
Whorl
Central pocket loop
Double loop
Lateral pocket loop
Composite
Accidental
2. Collect fingerprints using ink pads and placing their fingerprint on an index card.
3. Record name of person, finger, right or left hand, and type of fingerprint. For example:
Amy Urling
Right Ring Finger
Ulnar Loop