1. Fingerprints

3. Fingerprinting
System of identification based on the classification of finger ridge patterns

4. Fundamental Principles of Fingerprints
No two persons have identical ridge patterns.
A fingerprint remains unchanged during a person’s lifetime.
Fingerprints have general ridge patterns that can be systematically classified.

5. What are Fingerprints?
An impression left on any surface that consists of patterns made by the ridges on a finger
Ridge: appears dark in an images
Valley: appears light in an image

6. Giant Balloon Fingerprints
Activity
Giant Balloon Fingerprints

7. Human Skin
The epidermis (outer layer) and dermis (inner layer) determine the form and pattern of ridges on the surface of skin
Fingerprints develop in the human fetus (starting the 10th week)
Other prints: palms of the hands, soles of feet, lips, ears

8. Ten Card
A form used to record and preserve a person’s fingerprints

9. Activity: Making a Ten Card
Use ink strips to print each finger on the handout provided.

10. Fingerprint Patterns
Three classes:
Loops
Whorls
Arches

11. National Population (%)
Fingerprint Data
Fingerprint Type
Total #
Classroom Total #
Classroom %
National Population (%)
Loop
Whorl
Arch

12. National Fingerprint Data
National Population:
Loops (65%)
Whorls (30%)
Arches (5%)

13. Fingerprint Patterns

14. Ridge Characteristics

15. Minutiae Minutiae: points where print ridges come together or end
Minutiae points considered to be the “uniqueness” of an individual
Also called “Points”
FBI have found that no two individuals have more than 8 common “Points”

16. Minutiae Points

18. Latent Fingerprints

19. Activity: Make a Latent Print
Follow instructions to make a latent print on a clean surface.

20. Types of Fingerprints Patent (Visible) Print Impressed (Plastic) Print
Latent Print

21. Patent (Visible) Print
Finger comes in contact with medium (blood, dirt, ink, grease) and leaves visible impression

22. Plastic (Impressed) Prints
Indentations left in clay, wax, paint, soap, putty or other soft pliable surfaces
Can be viewed or photographed

23. Latent Print
Fingerprint made by the deposit of oils and/or perspiration
Invisible to the naked eye
Made visible by dusting, fuming or other chemical reagents

24. Detection of Latent Prints
Fingerprint powders (colored, magnetic, fluorescent dyes)
Iodine Fuming
Ninhydrin
Cyanoacrylate (superglue) fuming
Silver Nitrate

25. Detection of Latent Prints

26. Studying a Latent Print

27. Studying a Latent Fingerprint
Using the fingerprint brush and black powder, lightly dust the fingerprint (use a circular motion)
Press and lift the print off of the surface using clear tape.
Tape your latent print into your lab notebook.
Identify your print pattern as either a loop, arch or whorl.
Repeat with magnetic powder and pen.

28. Latent Print Recovery Lab
Using chemicals to detect a latent print:
Type
How does it work?
Test Sample
Safety Warning
Cyanoacrylate
Reacts with amino acids
Glass Slide
Do not inhale or get on your skin
Ninhydrin
Reacts with amino acids (proteins) found in sweat
Paper
Iodine Crystals
Reacts with oils
Toxic to inhale or ingest

29. Analysis of Lab:
For each station, write a paragraph that includes the following ideas:
Explain the procedures used to recover the print.
Describe what you observed.
What other surfaces do you think this method would work on?

30. Automated Fingerprint Identification System (AFIS)
In 1999, state AFIS computers were fully linked with the FBI database
Contains nearly 50 million fingerprint records
Each fingerprint scanned; digital minutiae data stored in computer

31. How is AFIS used? Unknown print is scanned and entered into computer
Computer searches AFIS system and produces a list of file prints that match closest with search print (takes 2 hours)
Fingerprint expert examines prints and makes final verification on print’s identify

32. Mobile Fingerprint Identification Used by police officers in the field to search AFIS and get a positive identification on a suspect.

33. Fingerprint FAQs Fingerprints dissolved by acid will grow back
Scars on fingers make prints even more unique