1 / 83

Fingerprints

Fingerprints. Do Now (5 mins). Fingerprints are found at a crime scene. What type(s) of evidence are fingerprints? Why?. Fingerprints. Physical evidence Trace evidence Why trace ?. Fingerprint Principles (3).

shina
Télécharger la présentation

Fingerprints

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Fingerprints

  2. Do Now (5 mins) Fingerprints are found at a crime scene. What type(s) of evidence are fingerprints? Why?

  3. Fingerprints Physical evidence Trace evidence Why trace?

  4. Fingerprint Principles (3) According to criminal investigators, fingerprints follow 3 fundamental principles:

  5. Fingerprint Principles (3) 1. A fingerprint is an individual characteristic; no two people have been found with the exact same fingerprint pattern.

  6. Fingerprint Principles (3) 2. A fingerprint pattern will remain unchanged for the life of an individual; however, the print itself may change due to permanent scars and skin diseases.

  7. Fingerprint Principles (3) 3. Fingerprints have general characteristic ridge patterns that allow them to be systematically identified.

  8. Ridges – unique patterns of lines in fingerprints

  9. Video #1, Video #2

  10. On Your Own… • After watching the two videos, explain the following statement: • “Immigrants in Lawrence, MA have frequently and unsuccessfully attempted to alter their fingerprints.” • Why would it be so common? • Why is it so often unsuccessful?

  11. Do Now (5 mins) • Can your fingerprints be duplicated? • Can your fingerprints be removed? • Explain why/why not.

  12. 8th Grade Forensic Science Ridgeology A Closer Look at Fingerprints T. Trimpe 2007 http://sciencespot.net/ Image from ftp://sequoyah.nist.gov/pub/nist_internal_reports/ir_6534.pdf

  13. Ridgeology: The study of the uniqueness of friction ridge structures and their use for personal identification.1

  14. Fingerprints: • made of a series of ridges and valleys on the surface of the finger. • Are unique because of.. a) pattern of ridges and valleys b) minutiae points, which are points where the ridge structure changes.

  15. minutiae • are major features of a fingerprint

  16. Automated Fingerprint Identification System (AFIS) a computerized system capable of reading, classifying, matching, and storing fingerprints for criminal justice agencies.  http://www.fdle.state.fl.us/CrimeLab/images/fingerrint%20comparison%20for%20afis.jpg

  17. Comparison There are no legal requirements in the United States on the number of points. Generally, criminal courts will accept 8 to 12 points of similarity. 16

  18. Try It! 1 – Blow up your balloon about halfway and twist the end to keep the air from coming out. Do not tie it off! 2 – Use an ink pad to make a print with all of your fingers and label each one with a permanent marker. Write your name on the balloon as well. 3 – Blow up the balloon to full size and tie the end. 4 – Analyze the fingerprints to find several ridge structures that we have discussed. Use a highlighter to mark these structures on your “My Prints” worksheet. Think About It! Which ridge structures were most common in your fingerprints? Which ridge structures were most common in your group? Were there any structures that were not found in any of the fingerprints? Balloon Fingerprint Activity: http://www.msichicago.org/fileadmin/Education/learninglabs/lab_downloads/fingerprint_analysis.pdf

  19. Balloon Prints • After putting your print on a balloon, blow up the balloon. • Describe 3 structures in your fingerprint that stand out.

  20. Do Now (5 mins) • How is a ridge different from a valley? • Name THREE things that make your fingerprint unique

  21. Ridge Characteristics Use these characteristics as points of identification when comparing fingerprint samples. The more points you can find in common, the better the match!

  22. Crossover Core Bifurcation (fork) Ridge ending Scar Island Delta Pore Ridge Characteristics EXAMPLE http://cnx.org/content/m12574/latest/properties.jpg

  23. Two bifurcations • One trifurcation • One eye • One island (dot) • TWO deltas

  24. http://www.dkfz.de/tbi/projects/bmcv/images/iu_it246_04s_fingerprint1.jpghttp://www.dkfz.de/tbi/projects/bmcv/images/iu_it246_04s_fingerprint1.jpg How many ridge characteristics can you identify in this fingerprint?

  25. Do Now (5 mins) • Describe the difference between a delta and a bifurcation.

  26. Do Now (5 mins) • Without looking back at notes, draw the following: • Bifurcation • Trifurcation • Island (Dot) • Eye

  27. Arch Plain arch Tented arch Loop Radial Loop Ulnar loop Whorl Plain whorl Central pocket Double loop Accidentical Fingerprint Classes There are 3 specific classes for all fingerprints based upon their visual pattern: arches, loops, and whorls. Each group is divided into smaller groups as seen in the lists below.

  28. Loop A loop must have one or more ridges entering and exiting from the same side. Loops must have one delta. Types Radial—opens toward the thumb Ulnar—opens toward the “pinky” (little finger) Which type of loop is this, if it is on the right hand? Left hand? 27

  29. Loops - one delta - one or more ridges that enter and leave on the same side. for their positions related to the radius and ulna bones. Delta Ulnar Loop (Right Thumb) Loop opens toward right or the ulna bone. Radial Loop (Right Thumb) Loop opens toward the left or the radial bone.

  30. Whorls -form a complete circuit - have at least two deltas. Central Pocket Whorl Plain Whorl

  31. Whorls – Part 2 Double Loop Whorl Accidental Whorl Double loop whorls are made up of any two loops combined into one print. Accidental whorls contain two or more patterns (not including the plain arch), or does not clearly fall under any of the other categories. Delta Delta

  32. Spike or “tent” Plain Arch Tented Arches Arches • simplest type of fingerprints that are formed by ridges • - No deltas are present.

  33. Arch An arch has ridges that enter on one side of the finger and cross to the other side while rising upward in the middle. - NO DELTAS! • Types: • Plain • Tented 32

  34. Arch Loop Whorl

  35. Fingerprint Factoid • 60% of people have loops • 35% have whorls • 5% have arches

  36. Fill in the following table…

  37. Identify each fingerprint pattern. A

  38. Identify each fingerprint pattern. B

  39. Identify each fingerprint pattern. C Right Hand

  40. Do Now (5 mins) • Next slide

  41. Identify each fingerprint pattern. D

  42. Identify each fingerprint pattern. E

  43. It’s time to makesome prints! Avoid Partial Prints GOOD PRINTGet as much of the top part of your finger as possible!

  44. Directions 1st – Roll the “pad” portion of your thumb over the ink pad from the left side of your thumb to the right. You do not have to push down really hard! 2nd – Roll the “pad” portion of your thumb from the left side of your thumb to the right in the correct box on your paper to make a thumbprint. 3rd – Continue this process to make a fingerprint of all ten fingers on the “My Prints” worksheet. 4th –Use your notes and a magnifying lens to help you figure out what type of pattern is found in each of your fingerprints. Label each one with the pattern’s name.

  45. Do Now (5 mins) Why do we leave fingerprints? Example) smudges on your cell phone

  46. Answer: Because our hands naturally produces oils These are called secretions

  47. Why Do We Have Fingerprints?

  48. Most secretions come from three glands: 1. Eccrine—largely water with both inorganic and organic compounds Most important for fingerprints.

  49. 2. Apocrine—secrete pheromones and other organic materials. Most secretions come from three glands:

  50. Most secretions come from three glands: 3. Sebaceous—secrete fatty or greasy substances.

More Related