Forensics: Fingerprints

Fingerprints are individual characteristics, they are unchanged througout life, and they have individual ridge patterns that classify them.

3 principles of fingerprints:

Arches, whorles, and loops

Kinds of fingerprint patterns:

Plain arch, tented arch

Types of arches:

Radial loop, ulnar loop, double loop, accidental loop

Types of loops:

Plain whorl, central pocket whorl

Types of whorles:

60%

Loop %

35%

Whorl %

5%

Arch %

Ridgeology

The study of the uniqueness of friction ridge structures and their use for personal identification

Minutiae

Points where the ridge structure changes, small characteristics/details, friction ridges

Points of similarity/identification

Points where minutiae on two different prints match

Min. 16

UK standard of points of identification

Min. 12

Australia standard of points of identification

AFIS

(Automated Fingerprint Identification System) countrywide, scan and search fingerprints, maintained by FBI (IAFIS)

Core, ending/starting ridges, forks, deltas, dots/islands, enclosures, bridges, crossovers, hook, eye

Ridge characteristics (examples)

Latent prints

Impressions left by friction ridge skin on a surface such as glass, door, requires enhancement

Camel hair

Most common hair used in brushes

1910, Chicago

When was the first US crime solved with fingerprints?

1000 years ago to China

How far back do fingerprints date back to?

Europe 17th-18th centuries

Where did America get fingerprint methods from?

Sir William Herschel

Who was the first European to use fingerprints as an identification method?

Sir Francis Galton, 1892

Who wrote a book called "Fingerprints" and when?

1892, Argentina

When was the first crime solved with fingerprints?

Patent prints

visible prints, no needed enhancement

Plastic prints (impressions)

prints left on a soft, receiving surface, no enhancement needed.

Surface

Most important factor to developing a print?

Powder dusting, Magnetic brush, Small Particle Reagent (SPR), and Mikrosil

Physical methods of print development?

Powder dusting

Done on a smooth, nonporous surface (plastic/metal)

Magnetic brush

Done on a smooth, nonporous surface

Small Particle Reagent (SPR)

Done on a surface that was previously wet/is wet

Mikrosil

Done on an irregular surface

Iodine fuming, Ninhydrin, Cyanoacrylate (super glue)

Chemical methods of print development?

Iodine fuming

Reacts with lipids, doesn't last long on nonporous surfaces

Ninhydrin

Reacts with amino acids, usually develop prints in good quality, sprayed ports surface

Cyanoacrylate (super glue)

Vaporizes with fumes on a nonporous, solid surface

Alternate light source, laser/luminescent nanoparticles

Other methods of print development?

Bloody fingerprints

Special situation development methods?

Bloody fingerprints

Put a time on the crime, enhanced with peroxidase which doesn't interfere with blood type/etc

paper/cardboard

ninhydrin

plastic

magnetic powder

wet surface

small particle reagent (SPR)

leather/vinyl

mikrosil

blood

peroxidase

untreated wood

ninhydrin

treated wood

standard powder brush

dark colored nonporous surface

fluorescent powder

glass, light metals

standard powder brush

Palms of hands, soles of feet, bite marks, lip prints, retina patterns, biometrics (details), toes

Other patterns on the body that can be used for personal identification?

ACE - V

Analysis, comparison, evaluation, & verification. Used when comparing prints/looking for match.