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Forensic Science

Forensic Science

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Forensic Science

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    1. Forensic Science

    2. Fingerprint Principles According to criminal investigators, fingerprints follow 3 fundamental principles: A fingerprint is an individual characteristic; no two people have been found with the exact same fingerprint pattern. 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. Fingerprints have general characteristic ridge patterns that allow them to be systematically identified.

    3. 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.

    4. Interesting Info Did you know? Dactyloscopy is the study of fingerprint identification. Police investigators are experts in collecting dactylograms, otherwise known as fingerprints.

    5. Arches

    6. Loops

    7. Whorls

    8. Whorls Part 2

    9. Identify each fingerprint pattern.

    10. Other Systems of Identification DNA- can be extracted from saliva, blood, semen, or hair Dental Records Handwriting Voice Analysis Note: None of these are as conclusive as fingerprints!!!

    11. Fingerprinting in Animals Koala Bears have prints strikingly similar to humans Horses are identified by their snout Whales are identified by their fluke

    12. Fingerprint Files The Department of Justice began a fingerprint file in the early 1900s The FBI began a fingerprint file in 1930, which is now considered to be the largest collection of fingerprints in the world

    13. Removing Fingerprints From the Crime Scene Most commonly, latent prints are recovered from the scene of a crime Latent prints are prints left by the oils in your skin that are invisible to the unaided eye They need to be lifted in order to be visualized

    14. Types of Prints Visible Prints: These are found when the finger deposits a visible material such as ink, dirt, or blood onto a surface Plastic Prints: This occurs when a fingerprint in impressed into a soft surface such as clay, soap, wax, or dust. Latent Prints: These prints are usually invisible to the unaided eye and are caused by depositing oil on surfaces that are touched

    15. Lifting Latent Prints Absorbent Surfaces These prints need to be fumed using superglue, iodine, or physical developer The chemicals react with the oils in the skin when heated in a chamber to visualize the print Examples of surfaces that are fumed: clothing, paper Non Absorbent Surfaces These prints can be dusted with powder and a brush and lifted with tape Examples of surfaces that are dusted: wood (table, chairs), glass (windows, tableware), plastic, metal (shotgun, knife, doorknob)

    16. A closer look at fuming

    17. Formation of Fingerprints Fingerprints are formed before birth, during the development of the hands. Fingerprints aren't actually formed in the skin, but are caused by ridges in the flesh underneath the skin. Genetics plays some part in their formation, but even identical twins (who have identical DNA) have different fingerprints. Fingerprints are formed on an fetus at about 5 months into the gestation.

    18. Can a person change or remove their fingerprints? YES Very difficult to remove all ridge characteristics You would have to remove 5 of the 7 layers of the epidermis to damage the fingerprint pattern People have tried burning in acid, using metal files, skin grafting NO Nearly impossible to remove them entirely Even burning in corrosive acid can still leave fingerprint patterns undamaged in spots To identify a print police need to match at least 12 minutae points.

    20. Directions