Intro to Forensics - Fingerprints

Henry Fauld, 1880

Who suggested fingerprints could be used in what year?

Francis Galton, 1892

Published book Finger Prints. Conducted the first definitive study of fingerprints and their classification. Gave proof of their uniqueness. (what year?)

True

True or False: it is virtually impossible to physically remove one's fingerprints

Mix of sweat and oil is left on surface in outline of the ridges

How are fingerprints transferred?

Loop

Ridge enters from one side, curves back, exits same side

Arch

Ridge enters from one side, exits other (plain)

Whorl

More complex ridges that cannot be classified as arches or loops

Tented arch

Similar to the plain arch, but has a spike in the center

Ulnar loop

Opens toward little finger

Radial loop

Opens toward the thumb

Double loop whorl

Made up of any two loops combined into one print

Plain whorl

Circular whorl pattern

Central pocket loop whorl

Plain whorl surrounded by a loop

Accidental whorl

A mix of different patterns. Cannot be classified as any other pattern.

Henry System

Primary level of fingerprint classification (all 10 fingers); each finger is assigned a number, each number assigned a value based on if there is a whorl or not, expressed as a fraction (numerator: sum of even finger plus 1; denominator: odd fingers plus 1)

Minutiae

Individualizing details within fingerprint patterns

Ridge ending

Type of minutiae where the ridge suddenly stops

Bifurcation

Type of minutiae where the ridge splits

Island (fingerprint)

Type of minutiae where the ridge splits and comes back together; or an isolated short ridge (a dot is a very small island)

Crossover

Type of minutiae; point where 2 ridge units intersect

AFIS (Automated Fingerprint Identification System)

A computer system for storing and retrieving fingerprints

True

To be legally acceptable, a fingerprint must be identified by a trained expert.

Patent or visible prints

Print left behind when a person touches visible fluid (ex: blood)

Plastic prints

Ridge impressions left on a soft material such as putty, wax, soap, or dust

Latent prints

Prints that are not visible to the naked eye

RUVIS (Reflected Ultraviolet Imaging System)

Aids in detecting latent prints without chemicals or powder; uses UV light

Prints are dusted, photographed, and lifted with tape.

What is the standard procedure for collecting fingerprint evidence at a crime scene?

Ninhydrin

A chemical reagent used to develop latent fingerprints on porous materials by reacting with amino acids in perspiration; dissolved in solvent like acetone or methanol; forms Rhuman's purple; can be treated with zinc chloride to create a fluorescent zinc complex

Super-glue fuming

A technique for visualizing latent fingerprints on nonporous surfaces by exposing them to cyanoacrylate vapors (acryalate polymerizes on the print which preserves the print); can be done with chambers or portable wands (wands are unreliable)