1. Mr. Ross Brown Brooklyn School for Law and Technology
Unit 6: Fingerprints
Mr. Ross Brown
Brooklyn School for Law and Technology

2. Why are fingerprints so useful?
2 May 2016
Do now: Other than fingerprints, what effective ways can we identify individuals accurately?

3. In this unit we will learn about:
The history of fingerprinting
Principles of fingerprints
Individuality
Permanency
Patterns
Fingerprint classification
Methods of detection
Methods of recording

4. Why are fingerprints so useful?
History
1880s, full body portrait (anthropometry)
Early 20th century, police begin using fingerprints
In the beginning, police needed luck to get good prints
Scientists studied patterns of anatomy so they could develop means of recording them

5. Why are fingerprints so useful?
1901: New York City Civil Service Commission used them on work applications
1924: New FBI begins collecting fingerprint records. Today the world’s largest collection.

6. Why are fingerprints so useful?
1999: United States v. Byron C. Mitchell. Defendant’s attorneys argue against admissibility of fingerprints. Judge upholds decision, stating ridges are permanent and unique.

7. What are the fundamental principles of fingerprints?
3 May 2016
Do now: What are some ways to avoid leaving your fingerprints if you are committing a crime? You can think about methods you’ve seen in movies, or ideas of your own.

8. What are the fundamental principles of fingerprints?
First principle: a fingerprint is an individual characteristic
Scientists have calculated 64 billion possible fingerprint combinations!
In the last 90 years, no two common sets have been found
Individuality is based on minutiae, or small details, in ridge characteristics

9. What are the fundamental principles of fingerprints?

10. What are the fundamental principles of fingerprints?

11. What are the fundamental principles of fingerprints?
Primary fingerprint characteristics
Arch, Loop, Whorl

12. What are the fundamental principles of fingerprints?
4 May 2016
Do now: What type of thumbprint do you have? Refer to yesterday’s notes if you are not sure. If relevant, is yours “left or right?” Compare with the folks around you.

13. What are the fundamental principles of fingerprints?
Second Principle: Fingerprints remain unchanged for life
Fingerprints are the result of friction ridges
Hills (or ridges) and valleys (or grooves)

14. What are the fundamental principles of fingerprints?
Fingerprints are left by sweat and oil on your hands. “Latent fingerprints”, hidden under normal inspection
Altering fingerprints is very difficult

15. What are the fundamental principles of fingerprints?
Third Principle: fingerprints have general patterns, which helps us classify them
65% of population has loops
30-35% have whorls
5% have arches

16. What are the fundamental principles of fingerprints?
Loops
Ridge enters from one side, recurves, and exits from the same side. If it opens toward thumb, it’s radial; toward pinky is ulnar
Contains a delta where ridges diverge into loop
Delta

17. What are the fundamental principles of fingerprints?
Whorls
4 types: plain, central pocket loop, double loop, and accidental
Minimum of two deltas

18. What are the fundamental principles of fingerprints?
Plain and Central Pocket Whorls have at least one ridge that makes a complete circuit.

19. What are the fundamental principles of fingerprints?
Double Loop is as its name implies (duh!)
Accidental is two or more patterns
May contain loop, whorl, and arch

20. What are the fundamental principles of fingerprints?
Arches
Least common. Occur in two ways, plain & tented
Plain is smooth, tented spikes up, <90°

21. What are the fundamental principles of fingerprints?
Primary classification of fingerprints
All the fingerprints in the world can be broken down into 1,024 groups.
Numerical value assigned based on presence or absence of a whorl pattern

23. What are the fundamental principles of fingerprints?

24. What are the fundamental principles of fingerprints?

25. What are the fundamental principles of fingerprints?
What are the limitations of a 10-finger classifications system?
Typically we don’t find more than one print at a crime scene
Some people are missing fingers

26. What are the fundamental principles of fingerprints?
Automated Fingerprint Identification System
AFIS
Electronic scanner that converts fingerprint images into digital minutiae showing ridge details at terminations (ridge endings) and branches (bifurcations)

27. What are the fundamental principles of fingerprints?