Fingerprints Fingerprints What are fingerprints Friction ridge skin

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Fingerprints

Fingerprints

Fingerprints What are fingerprints? § Friction ridge skin pattern § Found on fingers, palms,

Fingerprints What are fingerprints? § Friction ridge skin pattern § Found on fingers, palms, toes, soles of feet. Composed of ridges (hills) and furrows (valleys) § Black = Ridges White = Valleys

Fingerprints What are fingerprints? § § § Develop in early embryonic development. Pattern based

Fingerprints What are fingerprints? § § § Develop in early embryonic development. Pattern based on genetics, detail somewhat random Identical twins do not have identical fingerprints

Fingerprints How are fingerprints analyzed? Categorized by pattern and minutiae

Fingerprints How are fingerprints analyzed? Categorized by pattern and minutiae

Fingerprints How are fingerprints analyzed? Patterns Arch Loop Whorl

Fingerprints How are fingerprints analyzed? Patterns Arch Loop Whorl

Fingerprints How are fingerprints analyzed? Minutiae Bifurcation Dot Ridge Ending Island

Fingerprints How are fingerprints analyzed? Minutiae Bifurcation Dot Ridge Ending Island

Fingerprints There are 3 types of fingerprints Visible – left by dirt, grease, blood,

Fingerprints There are 3 types of fingerprints Visible – left by dirt, grease, blood, etc. 1. § Does not need processing

Fingerprints There are 3 types of fingerprints Impression – indentation in soft material (butter,

Fingerprints There are 3 types of fingerprints Impression – indentation in soft material (butter, putty, tar, etc. ) 2. § Does not need processing

Fingerprints There are 3 types of fingerprints 3. Latent – requires processing to make

Fingerprints There are 3 types of fingerprints 3. Latent – requires processing to make visible and suitable for analysis

Fingerprints > Analysis What are the invisible components? Multiple sweat glands secrete onto fingers,

Fingerprints > Analysis What are the invisible components? Multiple sweat glands secrete onto fingers, palms, etc. Sweat contains: § § Inorganic ions (Na+, Cl -) Proteins, amino acids § § Lipids Other

Fingerprints > Analysis Physical Development: Dusting § Apply powder to latent print or area.

Fingerprints > Analysis Physical Development: Dusting § Apply powder to latent print or area. § Powder adheres to print. Brush and Powder

Fingerprints > Analysis Chemical Development: Silver Nitrate 1. § § No longer used often

Fingerprints > Analysis Chemical Development: Silver Nitrate 1. § § No longer used often (messy, not sensitive) Silver reacts with Cl - ions in print

Fingerprints > Analysis Chemical Development: Iodine Fuming 2. § § § Iodine sublimes (solid

Fingerprints > Analysis Chemical Development: Iodine Fuming 2. § § § Iodine sublimes (solid → gas) Iodine reacts with lipid components; becomes trapped in the print. Fuming wand or chamber Dirty Brown Color

Fingerprints > Analysis Chemical Development: Ninhydrin 3. § § § Reacts with amino acids;

Fingerprints > Analysis Chemical Development: Ninhydrin 3. § § § Reacts with amino acids; purple color Painted or sprayed on area Heated to react

Fingerprints > Analysis Chemical Development: Super glue fuming 4. § § § Fumes with

Fingerprints > Analysis Chemical Development: Super glue fuming 4. § § § Fumes with heat or base (Na. OH) Fumed in cabinets Off-white print

Fingerprints > Collection of prints: Tape lift: § § Tape placed over developed print

Fingerprints > Collection of prints: Tape lift: § § Tape placed over developed print Tape then placed on white card.

Silver nitrate fingerprinting Dip finger in salt water n Let air dry n Press

Silver nitrate fingerprinting Dip finger in salt water n Let air dry n Press finger onto piece of paper n Put a drop of silver nitrate onto paper n Put under black light for 10 minutes n

Iodine fuming finger prints Rub finger on oily part of skin n Press finger

Iodine fuming finger prints Rub finger on oily part of skin n Press finger onto piece of paper n Place paper in beaker with iodine crystals n Cover back up n Remover paper in 5 minutes n