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Criminal Investigation

Criminal Investigation. CJUS 201 Fingerprints Part 12. Fingerprints. Friction ridge skin - hands: fingers, palms - feet: toes, soles, heels a. Side opposite fingernail : “ bulb” - friction ridge outlines b. Two layers of skin - inner / outer (1) Epidermis.

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Criminal Investigation

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  1. Criminal Investigation CJUS 201 Fingerprints Part 12

  2. Fingerprints • Friction ridge skin - hands: fingers, palms - feet: toes, soles, heels a. Side opposite fingernail: “bulb” - friction ridge outlines b. Two layers of skin - inner / outer (1) Epidermis

  3. Prints, cont. - contains ridges - 2 mm thick (2) Dermis - demal papillar - origination - scars / disease c. Uses (1) Friction ridges

  4. Prints, cont. - leaves impression - body secretions - material touched (2) Identification - permanent / individual - form on fetus (3) Hands / feet means to ID - fingers routinely used

  5. Prints, cont. • Prints - exact impression / image a. Most common means - perspiration - 99% water (1) Oils / chemicals - 1% amino acids / salts (2) Outside contaminants

  6. Prints, cont. b. Types of surface (1) Nonporous - most productive (2) Porous - chemical treatment (3) Plastic - photograph - cannot be developed

  7. Prints, cont. c. Impression - friction ridges - inside of fingers (1) Transferred - deposit of perspiration (2) Duplicated - by this - other substances

  8. Prints, cont. • Files maintained - sole purpose a. Arrest - WASIC - NCIC b. State requirements - employment - driver’s license - certificates

  9. Prints, cont. c. Professional license - health care - construction - accounting - education d. Military service - enlisted / civilian • Types of prints - visible / latent / plastic

  10. Types, cont. a. Latent prints - law enforcement - crime scene (1) Process - detecting / raising / lifting (2) Term - invisible - fingertips - secretions / contaminants

  11. Types, cont. b. Two sources of materials - natural / environmental (1) Natural - perspiration - body residue (acids / fats / salts) (2) Environmental - foreign matter - dust / soot / pollen / cooking oils

  12. Types, cont. c. Personal factors - print left or not (1) Physiology - perspire? (2) Surface type - suitable - unpainted wood / paper / textured - glass / enamel / metal / glossy

  13. Types, cont. (3) Pressure - firm / not heavy - ridges light - distort detail • Fingerprint classification - three primary patterns (types) a. Arch - ridges enter one side - rise / curve in center

  14. Classification, cont. - flow out opposite side (1) Plain / tinted (2) 5% – 10% b. Loop - enter on either side - make loop - flow out opposite side - same side

  15. Classification, cont. (1) Plain / double loop / central pocket loop / accidental (2) 60% - 65% c. Whorl - enter on both sides - form circle - flow out opposite side (1) 25% - 30%

  16. Classification, cont. • Fingerprint patterns - used to classify - not individualize a. Counted: core to delta - points of distinction - necessary for ID (1) France = 17 (2) England = 16

  17. Patterns, cont. (3) Spain = 10 to 12 (4) United States = 12 (5) Washington State = 12 b. Evidentiary value - crime scene - victim - person identified

  18. Patterns, cont. • Methods of classifying - mathematical formula - shapes / position / size a. Characteristics - unique properties in ridge detail - different from each other - different from one another b. Types - ending ridge

  19. Methods, cont. - bifurcation - dot - short ridge - island (enclosure) c. FBI: catalog of prints - NCIC (1) Taken in US (2) Vary: state to state

  20. Methods, cont. d. Collection: two purposes - evidence of patterns - positive identification • Lifting of fingerprints a. Dusting - specific steps (1) Brush is clean

  21. Lifting, cont. - roll handle (2) Shake powder - loosen (3) Apply lightly - follow contour lines (4) Remove excess (5) Photograph

  22. Lifting, cont. b. Lifting - commercial lift card (1) White / black background - color of powder - rubber lifter (2) Transparent tape - different sizes - palm size

  23. Lifting, cont. c. Transfer to card - identification • Chemical development - paper / cardboard / unpainted wood a. Iodine method - crystal fumes - absorbed by oils - yellowish/brown print (fade) - will fade / photograph immediately

  24. Development, cont. b. Ninhydrin - organic chemical - amino acids / protein (1) Kept 2 hours: room temperature - 1 to 3 days to fully develop (2) Purple-colored print - photograph immediately c. Silver nitrate

  25. Development, cont. - sodium chloride - perspiration - organic material (1) Reddish-brown - disappear 2 hours (2) Ultra-violet light - photograph immediately d. Cyanoacrylate fuming

  26. Development, cont. - esters / resins - “super glue” (1) Fuming chambers - vehicles - pads opened / placed (2) Non-porous surfaces - photographed - dusted - alter other biological evidence

  27. Development, cont. e. Radiation - raises prints (1) Ultraviolet rays - shows prints - dusted (2) Laser - vitamins in perspiration - skin / paper products

  28. Fingerprint Systems • AFIS - Automated Fingerprint Identification Sys. a. Technicians - digitize information - inkless prints - scanned - electronic image - stored in data base - access: NCIS / WASIC

  29. Systems, cont. b. Suspect print - classified (arch / loop / whorl / etc.) - 12 matching characteristics - data base computer (1) Produce comparisons - several matches - technician examines (2) Scan 1 million in 4.5 minutes

  30. Systems, cont. • Assessing surface - three types a. Non-Porous - glass / plastic / polished metal - finished wood / processes paper (1) Textured - photograph (2) Smooth

  31. Surface, cont. (3) Curvature b. Porous - paper / wood / some painted surfaces (1) Chemical - photograph (2) Fluoresce - photograph

  32. Surface, cont. c. Plastic - putty / plastics / adhesives - paint (semi-hardened) / plaster (1) Photograph • Rolling prints - from ‘V’ outward a. Right hand - thumb = 1

  33. Rolling, cont. - index = 2 - middle = 3 - ring = 4 - little = 5 b. Left hand - thumb = 6 - index = 7 - middle = 8 - ring = 9 - little = 10

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