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Fingerprints

Fingerprints. “Fingerprints cannot lie, but liars can make fingerprints.” --- unknown. 1. Types of Fingerprints. There are 3 types of prints found by investigators at crime scenes:

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Fingerprints

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  1. Fingerprints “Fingerprints cannot lie, but liars can make fingerprints.” --- unknown 1

  2. Types of Fingerprints There are 3 types of prints found by investigators at crime scenes: 1. Patent – visible prints left on smooth surface when blood, ink or some other liquid comes in contact with the hands and is then transfer to the surface. 2

  3. 2. Plastic – actual indentations left in some soft material such as clay, putty, or wax. 3. Latent – hidden prints caused by the transfer of oil and other body secretions onto a surface. 3

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  6. Ridgeology A Closer Look at Fingerprints 6

  7. As we have learned in our first lesson, a fingerprint is made of a series of ridges and valleys on the surface of the finger. The uniqueness of a fingerprint can be determined by the pattern of ridges and valleys as well as the minutiae points, which are points where the ridge structure changes. Did you know? The koala is one of the few mammals (other than primates) that has fingerprints. In fact, koala fingerprints are remarkably similar to human fingerprints; even with an electron microscope, it can be quite difficult to distinguish between the two. Ridgeology: The study of the uniqueness of friction ridge structures and their use for personal identification.1 1Introduction to Basic Ridgeology by David Ashbaugh, May 1999 Image from http://www.cs.usyd.edu.au/~irena/minutia.gif

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  11. Fingerprint Minutiae 11

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  13. Fingerprints of suspects are taken by rolling each of the 10 fingers in ink and then rolling them onto a ten card. 13

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  15. Data Collection from Class Expected Percentages Loops – 65% Whorls – 30% Arches – 5% • How do your prints compare to the expected averages? 15

  16. Which pattern is the most common among the males in this class? • Which pattern is the most common among the females in this class? • How do the averages for each sex compare to the expected averages? • Describe how to improve this data collection so that results be more reliable? Copy and answer this question in the back of this page. 16

  17. Can Fingerprints Be Altered or Disguised? JohnDillinger, public enemy #1 in the 1930’s, tried to alter his fingerprints, but essentially he made his fingerprints even more unique. 17

  18. How reliable is fingerprinting as a means of identification? Fingerprint identification is not flawless, because people enter and analyze information and people make mistakes. Brandon Mayfield was falsely accused of involvement in the Madrid train bombing on the basis of the mistaken analysis of fingerprint evidence. 18

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  20. How are fingerprints analyzed? 20

  21. Fingerprinting has been used by law enforcement agencies for more than a century. 21

  22. How are latent fingerprints collected?Refer to Figure 6-15 • Dusting • photographing • Magnetic Powders • Ninhydrin • Cyanoacrylate • Silver Nitrate • Iodine Fuming 22

  23. Latent Prints • Latent fingerprints are those that are not visible to the naked eye. These prints consist of the natural secretions of human skin and require development for them to become visible. How to find and examine latent fingerprints at the crime scene? Dusting for prints • Traditional method • Dust (black, magnetic, fluorescent) • Prints are numbered, photographed, lifted with tape • Labeled and photographed showing location and order 23

  24. Powders - adhere to both water and fatty deposits. Choose a color to contrast the background. 24

  25. Most common identification method partly because they are cheap and fast. Powders stick to the oily components of the print. Black and silver most common depending on background although fluorescent and magnetic powders are fast becoming preferred. Must lift print with special tape or photograph. 25

  26. How to find and examine latent fingerprints at the crime scene? Super Glue • Also known as cyanoacrylate • Use portable fuming system • Large objects and items cant be removed from crime scene. • Method superior to dusting 26

  27. Cyanoacrylate Fingerprints Superglue Cyanoacrylate dissolves in the oils of the print to form very visible white ridges. Very sensitive method. 27

  28. Cyanoacrylate Fingerprints 28

  29. Iodine- fumes react with oils and fats to produce a temporary yellow brown reaction. Since iodine is highly vaporous in air, the fingerprint needs to be photographed immediately. However, this is an excellent method to locate latent fingerprints. 29

  30. Iodine Fingerprint 30

  31. How are latent fingerprints collected? Read the “Did you know” sections Pages 140 and 142. 31

  32. Videoclips Fingerprint Analysis A Man Without Fingerprints Fingerprints Determining Fingerprints Fingerprinting Using forensic evidence to solve crimes – video clip 32

  33. Review Questions • Can fingerprints be erased? Only temporarily; they will grow back if removed with chemicals • Is fingerprint identification reliable? Yes, but analysts can make mistakes • Can computers perform matches in seconds? No, but the FBI’s Integrated Automated Fingerprint Identification System (IAFIS or AFIS) can provide a match in 2 hours 33

  34. The Future of Fingerprinting • New scanning technologies • Yield detail in minute patterns • Reduce analytical mistakes • Analyze trace elements of objects on the skin 34

  35. The Future of Fingerprinting • Entirely new uses for fingerprints are being developed. • For Example: Fingerlocks 35

  36. Fingerprint Scanners Click here for video clip → 36

  37. Employees who punch the clock for absent or tardy co-workers are costly. This practice, called "Buddy Punching" or "Ghost Employees" is effectively controlled by Biometric Time Clocks. Touch and Go fingerprint readers 37

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  39. A USB key with a fingerprint reader is not new, but these small CR-FP2 and CR-FP3 USB keys received a sensor with a 1/10000000 precision. They nearly perfectly recognize your fingerprint. Also, Elecom announced the keys don’t retain the fingerprint in memory, which prevents people from accessing your data. 39

  40. Citizen Patrol groups participate in many special events within the community. In this photo, a C.O.P. is helping to fingerprint young children and teens at the request of their parents during a local safety fair. Many citizen patrol volunteers are trained to provide this type of service to the community and law enforcement. 40

  41. New Technology Live Scan System which allows police officers to compare a suspect’s fingerprints with millions of fingerprints on files. 41

  42. Technologies currently being developed that use other physical features to identify people includes: • Retinal patterns in the eye • Facial patterns • Veins in your palm 42

  43. Fingerprint Uses • Fingerprints are used to link a suspect to a scene. • To determine if the suspect has been previously arrested. • Fingerprints are also useful in • identifying bodies, • victims of mass disasters, and • amnesia victims who cannot remember their own identity. 43

  44. Click here for video clip ↓ No two people have identical fingerprints…not even identical twins. 44

  45. Photo taken through a dissecting microscope using a cellphone camera Assign Fingerprint Book Project 45

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