Fingerprinting. Chapter 6

Transcription

1 Fingerprinting Chapter 6

2 Sir William Herschel British officer in India. Used fingerprints for contracts. Began collecting fingerprints in Patterns unique to individual. Not altered by age.

3 Alphonse Bertillon Assistant clerk in the records office at the Paris Police Station Created a way to ID criminals in Used fingerprints and biometrics (measuring human anatomy). In 1902, solved the first murder using fingerprints. Also invented the mugshot!

4 Sir Francis Galton and Sir Edward Richard Henry Developed fingerprint classification system still used today in the U.S. and Europe (1888).

5 Fingerprints Friction Ridges lines on fingers. Help us grip objects. Imprint of a fingerprint consists of natural secretions of the sweat glands that are present on the friction ridges. Secretions are mainly water, oils, salts, and amino acids.

6 How Do Fingerprints Form? Formed when fetus is 10 weeks old (3 inches long). Fingerprints created in the basal layer. The basal layer grows faster than the epidermis on the outside and the dermis on the inside. Faster growth causes it to collapse and fold in different directions. Even twins have different fingerprints!

7 3 General Fingerprint Patterns Arches (5%) Ridges enter from one side & leave from the other with a rise in the center. Whorls (30%) Looks like a bull s eye. 2 Deltas Loops (65%) Most common Loops enter from either the right or the left & exit from the same side.

8 Rolled vs. Flat Fingerprints Rolled Flat (Plain) Latent

9 Ten Card

10 Arch Patterns Plain Arch Tented Arch Sharp spike at center of arch

11 Whorl Patterns Plain Whorl Central Pocket Loop Whorl Double Loop Whorl Accidental Whorl An imaginary line between deltas must touch a whorl ridge An imaginary line between deltas cannot touch a whorl ridge > 2 Deltas

12 Quick Anatomy Mini-Lesson!

13 Loop Patterns Radial & Ulnar Loops Radial Loop on right hand. Ulnar Loop on left hand. Ulnar Loop on right hand. Radial Loop on left hand.

14 These are all RIGHT thumbprints. What is the pattern? Plain Arch Tented Arch Ulnar Loop Radial Loop Plain Whorl Central Pocket Loop Double Loop Whorl Accidental Whorl

15 Fingerprint Types Class Data Look at your Right Thumb print on your Ten Card (Do not lose this Ten Card!). Class Data Expected Loop 65% Whorl 30% Arch 5%

16 Minutiae unique ridge patterns Fingerprint Identification 150 individual ridge characteristics on the average full fingerprint Match requires specific reference points. Minutiae

17 Minutiae (basic) Core - center of a loop or whorl Delta triangular region located near a loop Ridge Count Draw an imaginary line from the center of the core to the edge of the delta. Count the ridges along the imaginary line.

18 Minutiae (advanced) or Lake

19 Lab Identifying Ridge Details Intro: How to compare fingerprints the basics (5:44) Complete Lab

20 3 Types of Fingerprints Patent Fingerprints visible prints left on a smooth surface by blood, ink, etc. Plastic Fingerprints an indentation left in some soft material (clay, putty, wax, etc.) Latent (Hidden) Fingerprints oils and other body secretions are transferred to a surface; can be made visible by dusting with powders or using a chemical reaction.

21 How to Visualize Latent Fingerprints Dust surfaces to expose fingerprints. Use a color that contrasts with surface. Ex. Carbon dust (black) on white surface. Use tape to lift fingerprint. Place tape on card to preserve. How to Dust -- Phil Gilhooley (7:59) Magnetic powders can also be used. (2:46) Fluorescent Powder (0:27)

22 How to Visualize Latent Fingerprints Chemical Development of Prints Reaction with amino acids in sweat: Cyanoacrylate vapor - superglue (5:24) Ninhydrin (8:02) Reaction with salt (NaCl) in sweat: Silver nitrate (AgNO 3 ) produces a precipitate (AgCl) when reacts with NaCl, view under UV light. Combines with carbohydrates: Iodine fuming spray with starch solution to preserve color. (5:04)

23 Lab Latent Prints & Fingerprint Matching You do not need to bring paper or pencil. Safety & Disposal Do not get superglue on your hands. Be sure to clean up ALL black powder! Wipe down the lab benches! Complete Part A and Part B. CLEAN. Get your Ten Cards & Return to your Lab Station. Read through Part C (so you will know what to do). Wait until EVERYONE is done.

24 Latent Print Visualization Latent Prints (3:22) watch?v=w7wuurimcum

25 Reliability of Fingerprint Identification In 1995, 156 fingerprint examiners were given a test. 1 in 5 examiners made at least one false-positive identification. How do we try to reduce errors? The International Association for Identification provides fingerprint certification for all fingerprint examiners.

26 How are Fingerprints Analyzed? In 1987, the FBI had 23 million fingerprint cards on file. Manual searching could take as long as 3 months. Even fingerprint matching by computer takes longer than just a few seconds! In 1999, the FBI developed the Integrated Automated Fingerprint Identification System (IAFIS). Contains 47 million people s fingerprints. Fingerprints are stored and searched electronically. Get results in 2 hours.

27 How to Reduce Search Time The Henry Primary Classification System Based on the presence of whorls. Reduces search time. R. index R. ring L. thumb L. middle L. little R. thumb R. middle R. little L. index L. ring Add up the numerators. Add up the denominators. Add 1 to both the numerator & denominator Find your Henry Classification!

28 Altering Fingerprints John Dillinger Led a gang that robbed 24 banks in the 1930 s. Heard that workers in Cuban pineapple fields had their fingerprints destroyed by the chemical substances in the plants. But the workers fingerprints grew back! Put acid on fingertips to change their appearance. In the morgue, fingerprints were taken from Dillinger s body and compared to crime scene evidence.

29 New Technology Dr. Sue Jickells Things that criminals touch (explosives, cigarettes, drugs, etc.) leave traces behind on the skin. We can now detect whether a criminal is a drug user or has recently consumed alcohol through chemical testing of fatty acids left in fingerprints. Ex. Smokers secrete cotinine (produced when the body breaks down nicotine). Adults, children and the elderly lay down different types of organic compounds in the prints. Can also determine age?

30 (cont d) Laser Scanning Fingerprints from bullet casings: eature=endscreen&v=dlvhscu1sse (2:13) Other means of identification: Retinal pattern in eyes Pattern of veins in hand

31 Case Study Francesca Rojas Background: A trump card in a card game is a card that (when played) automatically wins. 1. What did Vucetich mean when he said I hold one trump card now, and I hope I shall soon have more.? 2. Who came up with the idea of the Ten Card? 3. Explain some differences between the Argentinian police system in the early 1900s and our current police system in the U.S.