Fingerprints Lecture Notes

Flashcards covering key concepts about fingerprints, their identification, and related scientific principles.

Anthropometry

A precise system of body measurements.

Reliability of Anthropometry

Based on the premise that the dimensions of the human bone system remained fixed from age 20 until death.

Francis Galton's book Finger Prints

Covers the anatomy of fingerprints, categorization into 3 patterns (whorl, loop, arch), uniqueness of prints, and methods for recording prints.

Will West case

Highlighted the downfall of anthropometry as measurements were susceptible to error despite visual similarities.

US v. Byron C. Mitchell

Significant for establishing that fingerprints are unique and permanent despite arguments to the contrary.

Three fundamental principles of fingerprints

1) No two fingerprints are identical; 2) Fingerprints remain unchanged during an individual's lifetime; 3) General ridge patterns allow systematic classification.

Minutiae

Fingerpint ridge characteristics used for identification.

Three individualizing factors for fingerprints

1) Identity; 2) Number; 3) Relative location.

JAI's stance on ridge characteristics

No valid basis for requiring a predetermined minimum number, as individual prints can vary widely.

Friction ridges purpose

To provide a firmer grasp and resistance to slippage.

Epidermis

The layer of skin that contains the friction ridges.

Components of latent prints

Perspiration and oils.

Permanently altering fingerprints

Impossible to fully change; attempts may create permanent scars which can still exhibit individual characteristics.

Fingerprint classification system

Created to accommodate more than 100,000 sets of files by converting ridge patterns into digits and letters.

AFIS matching process

Prints are scanned, converted to digital data showing ridge characteristics, and matched by a trained expert based on correlation.

LiveScan

An inkless device capturing digital images of fingerprints for quick processing by AFIS.

Potential issues with AFIS reliance

Over-reliance may lead to missed matches due to poor quality of file prints.

Processing latent prints on non-porous surfaces

Utilizes powders or superglue; porous surfaces require chemical treatments.

UV light for locating fingerprints

Helps identify prints on non-absorbing surfaces without chemicals or powders.

Fingerprint development technique - Powders

Applied lightly to non-absorbent surfaces using a brush for best color contrast.

Iodine fuming

Technique that adheres to oils in prints, but is not permanent.

Ninhydrin

A chemical reaction that produces purple-blue color with amino acids in perspiration.

Superglue fuming

Uses cyanoacrylate to develop prints on non-porous surfaces.

Chemically induced fluorescence

Involves applying a chemical to a print and using a light source to induce fluorescence.

Document preservation methods

Small objects should be preserved in entirety; large objects require lifting and photographic documentation.

Digital imaging benefits

Allows for background removal and enhancement of fingerprint details.

Creation of fingerprints

Established around week 24 of gestation through the development of dermal papillae.

Fingerprint uniqueness evidence

Galton's calculation suggests the existence of 64 billion different fingerprints, corroborated by extensive classification data.