1. Fingerprints Ch. 4 and some of Ch. 9

2. Journal Determine the Henry Number for the following: L W A A L A L W L A

3. Finger12345678910 If whorl is present 16 88442211

5. Objectives You will understand: –Why fingerprints are individual evidence. –Why there may be no fingerprint evidence at a crime scene. –How computers have made personal identification easier.

6. More Objectives You will be able to: –Define the three basic properties that allow individual identification by fingerprints. –Obtain an inked, readable fingerprint for each finger. –Recognize the general ridge patterns –Identify friction ridge characteristics and compare two fingerprints with at least ten points of identification. –Explain the differences among latent, plastic, and visible fingerprints. –Develop latent prints (make them visible) using physical and chemical methods.

7. Brief history Part of anthropometry Used as a legal signature in China 3000 years ago 1892, first publication on uses of fingerprinting

8. Fundamentals Dactyloscopy: the study of fingerprints A fingerprint is an Individual Characteristic –150 ridge characteristics per fingerprint –64 billion different combinations A fingerprint will (normally) remain unchanged during an individual’s lifetime

9. What you look for when comparing General ridge pattern –arch –loop –whorl Ridge characteristics Must have 8 identical ridge characteristics minimum to call it a “match” in court (but it’s not a legal definition)

10. Arch Friction ridges that enter on one side of the finger and cross to the other side while rising upward in the middle Do NOT have type lines, deltas, or cores. Subtypes –plain –tented

12. Loop Has one or more ridges entering and exiting from the same side. Have one and only one delta. Types –Radial—opens toward the thumb –Ulnar—opens toward the “pinky” (little finger)

14. Whorl Has at least two deltas and a core. Plain and central pocket –at least one ridge that makes a complete circuit Double loop –made of two loops Accidental –a pattern not covered by other categories.

16. LOOP WHORLARCH

17. Ridge Characteristics

19. Types Visible Plastic: left in a moldable surface, gives a negative impression Latent

20. Latent Prints Not visible to the naked eye. Consist of the natural secretions of human skin glands –Eccrine: secretes largely water, with both inorganic and organic. Found on palms of hands, feet. Most important for fingerprints. –Apocrine: secretes pheromones and other organic materials. Found in axial and genital regions. –Sebaceous: secretes fatty or greasy substances. Sprouts a hair.

21. Developing Latent Prints Idea is to make print stand out against its background Requires substances that interact with secretions Lasers and alternative light sources are used to view (find!) latent fingerprints. May be necessary to attempt more than one technique, done in a particular order so as not to destroy the print.

22. Chemical Developing Powders: adhere to both water and fatty deposits. Choose a color that contrasts with 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.

23. Chemical Developing Silver nitrate: reacts with chloride to form silver chloride, a material that turns gray when exposed to light. Cyanoacrylate: “superglue” fumes react with water and other fingerprint constituents to form a hard, whitish deposit.

24. Iodine Fingerprint

25. Ninhydrin Fingerprint

26. Cyanoacrylate Fingerprints

27. Other Types of 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

28. Palm Prints friction ridges can be identified and may be used against suspects

29. Retinal Prints The blood vessel patterns in the eye may be unique to individuals. They are used today for various security purposes.

30. AFIS Automated Fingerprint Identification System Uses scanner to convert image to digital minutiae that can be compared With AFIS: takes 20 minutes to search L.A. fingerprint database. Without AFIS: takes 67 years IAFIS—the FBI’s Integrated Automated Fingerprint Identification System, which is a national database of all 10-print cards from all over the country

31. Lip Prints