1. Fingerprints

2. 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

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

4. Categorized by pattern and minutiae
Fingerprints
How are fingerprints analyzed?
Categorized by pattern and minutiae

5. How are fingerprints analyzed?
Patterns
Arch
Loop
Whorl

6. How are fingerprints analyzed?
Minutiae
Bifurcation
Ridge Ending
Dot
Island

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

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

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

10. What are the invisible components?
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

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

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

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

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

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

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

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

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