Forensics Fingerprint Analysis Test

Main contributors to Fingerprint identification

• Sir Francis Galton- Conducted the first scientific study of Fingerprints; discovered they are not all the same

• Sir Edward Henry proposed a modified classification system which was adopted (Henry System)

Three Principles of Fingerprints

• A Fingerprint is an individual characteristic

• A fingerprint will remain unchanged during a persons lifetime

• Fingerprints have general ridge patterns that are used to be systematically classified

Why are fingerprints left on something we touch.

Because our bodies secret oils and sweat. When we touch a surface these transfer and leave behind an impression of the ridges.

What determines the individuality of a Fingerprint.

The arrangement of the ridge characteristics (minutiae)

Loops

• Ridges enter from one side, curve, and exit from the same side

• Ulnar loop- open toward the little finger

• Radial loop- open towards the thumb

Whorls

Spiral pattern with at least 2 deltas.

• Plain whorl, Central pocket, Double Loop, Accidental

Arches

Ridges enter from one side and exit the other with no deltas

• Plain and Tented arch

Types of fingerprints at crime scenes

• Patent- Visible without development (blood, paint, ink)

• Plastic- Impressions in soft material (wax, putty, soap)

• Latent- Invisible; composed of sweat/oils; require development

Most and least common Fingerprint types.

• Loops 65%

• Whorls 30%

• Arches 5%

Henry classification

Uses the presence of a whorl on the 10 fingers to generate a number. Even finger values +1 over odd finger values+1

Drawbacks of Henry classification

Requires all 10 fingers

Based primarily on whorls

Replaced by AFIS

Methods for developing latent prints

• Dusting- uses Smooth, nonporous surfaces, Black charcoal powder, aluminum powder and magnetic powder.

• Chemical- Used for porous surfaces. Knife handles, and Paper (Ninhydrin)

Why is it impossible to get rid of your fingerprints?

Becasue they are created deep in the skin. Even if the epidermis is damages they will regenerate. Attempting to get rid of them will create unique patterns

What type of prints are found in soft wax

Plastic

Are partial fingerprints useful.

Yes, A small section of minutiae can be matched to a known Fingerprint. but the more the better.

Ridge ending

Bifurcation

Delta

Eye

Dot

Island or short ridge

Bridge