1. Forensic Lab Investigations

2. Fingerprinting Been used for identification since the early 1900s Been used for identification since the early 1900s FBI Identification division began, in 1924, with 810,188 fingerprint files FBI Identification division began, in 1924, with 810,188 fingerprint files Currently, more than 250 million fingerprint records Currently, more than 250 million fingerprint records

3. Background Skin on palms, fingers, and feet have tiny surface ridges Skin on palms, fingers, and feet have tiny surface ridges Gives traction for walking and grasping Gives traction for walking and grasping Pattern is unique to each person Pattern is unique to each person

4. Why do we leave prints? Skin surface covered with oils, sweat, and amino acids which transfer to an object when touched Skin surface covered with oils, sweat, and amino acids which transfer to an object when touched Foreign substances (oil, blood, dirt, ink, etc.) Foreign substances (oil, blood, dirt, ink, etc.) Exact impression of surface ridge is left behind Exact impression of surface ridge is left behind

5. Can your fingerprints change? No, fingerprints will always remain the same. No, fingerprints will always remain the same. They may scar or have cracks. They may scar or have cracks. Can be masked with super glue or burnt off, but they will return Can be masked with super glue or burnt off, but they will return

6. Matching Prints There are no set matches of points that must be provided for court There are no set matches of points that must be provided for court The more you have the more convincing your evidence The more you have the more convincing your evidence Must show how the points match Must show how the points match

7. Types of Prints Fingerprint Impression Fingerprint Impression Arch, whorl, loop Arch, whorl, loop Categories: Categories: Loop, double loop, central pocket loop, tented arch, plain arch, plain whorl, accidental Loop, double loop, central pocket loop, tented arch, plain arch, plain whorl, accidental

8. In a whorl pattern, the ridges are usually circular In a whorl pattern, the ridges are usually circular In a loop pattern, the ridges enter from either side, re- curve and pass out or tend to pass out the same side they entered In a loop pattern, the ridges enter from either side, re- curve and pass out or tend to pass out the same side they entered In an arch pattern, the ridges enter from one side, make a rise in the center and exit generally on the opposite side In an arch pattern, the ridges enter from one side, make a rise in the center and exit generally on the opposite side

9. Tented Arch Tented Arch

10. Can you identify these prints? Can you identify these prints? A B C

11. Minutiae (Galton) Points Ridge characteristics that go into a little more detail than the arch, loop, and whorl classification Ridge characteristics that go into a little more detail than the arch, loop, and whorl classification Used for more precise identification Used for more precise identification

12. Types of Points Basic and comp osite ridge chara cteris tics ( minut iae) MinutiaeMinutiae ExampleExample MinutiaeMinutiae ExampleExample ridge endingridge ending bridgebridge bifurcationbifurcation double bifurcationdouble bifurcation dotdot trifurcationtrifurcation island (short ridge)island (short ridge) opposed bifurcationsopposed bifurcations lake (enclosure)lake (enclosure) ridge crossingridge crossing hook (spur)hook (spur) opposed bifurcation/ridge endingopposed bifurcation/ridge ending

13. Using Minutiae Poinnts Compare prints of the same finger and classification Compare prints of the same finger and classification One print may have as many as 100 minutiae points One print may have as many as 100 minutiae points No two fingers have the same pattern No two fingers have the same pattern

14. http://shs.westport.k12.ct.us/forensics/04- fingerprints/handout.htm http://shs.westport.k12.ct.us/forensics/04- fingerprints/handout.htm http://shs.westport.k12.ct.us/forensics/04- fingerprints/handout.htm http://shs.westport.k12.ct.us/forensics/04- fingerprints/handout.htm

15. Latent Prints Fingerprints found on a surface that aren’t visible to the naked eye. Fingerprints found on a surface that aren’t visible to the naked eye. Flashlight, UV light, or laser used to find prints Flashlight, UV light, or laser used to find prints Dusting procedure is most effective if prints are oily (50% of the time) Dusting procedure is most effective if prints are oily (50% of the time) Must be done carefully to not destroy the prints Must be done carefully to not destroy the prints

16. http://criminaljustice.state.ny.us/ojis/histo ry/fp_sys.htm http://criminaljustice.state.ny.us/ojis/histo ry/fp_sys.htm http://criminaljustice.state.ny.us/ojis/histo ry/fp_sys.htm http://criminaljustice.state.ny.us/ojis/histo ry/fp_sys.htm http://en.wikipedia.org/wiki/Henry_Classifi cation_System http://en.wikipedia.org/wiki/Henry_Classifi cation_System http://en.wikipedia.org/wiki/Henry_Classifi cation_System http://en.wikipedia.org/wiki/Henry_Classifi cation_System