Study Guide #7
Fingerprints

Dactyloscopy

Study of friction ridge patterns
        Fingerprints
        Palmprints
        Footprints
        Lipprints

Status of Fingerprint Science

At this time, fingerprint ridge characteristics are considered to be individual evidence
No set number of characteristics are required to match anymore
Rigorous scientific verification of underlying principle has not been accomplished

Basic Ridge Characteristics

12 Point Fingerprint Comparison

8 Basic Fingerprint Patterns

Arch Pattern

Loop Pattern

Whorl Patterns

10-print fingerprint card

Types of Fingerprints

Latent - cannot be seen with naked eye. Needs to be developed
Patent - visible print made in a material such as fresh paint or blood
Plastic - visible print impressed into soft material such as putty

Patent Print on Truck Bumper

Patent Print on Foil (Cocaine)

Development of Latent Prints

Powder methods
        Contrasting powder
        Magnetic powders

Chemical methods
        Silver nitrate - paper
        Ninhydrin
        Physical developer - paper

Development of Latent Prints

Superglue fuming
        Uses tank with superglue and heat
        Superglue coats fingerprint ridges with hard, whitish coating
        Print can then be treated with any chemical or powder method

Development of Latent Prints

Dye application followed by illumination by strong light source (e.G. Laser)
        Most common setup uses argon laser and Rhodamine 6G dye
        New light sources available - not as powerful as laser but more wavelength choices
Image captured by CCD camera and enhanced

Laser and Camera Setup

Argon Laser Enhanced Fingerprint

Enhancement of Fingerprint on Paper Using Argon Laser

AFIS

Automated fingerprint identification systems
        Uses dots and bifurcations to map print and correctly align
        Print is currently traced by hand
        Computer search gives most likely matches
        10-print cards manually searched
 

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