Fingerprinting Lab Midterm

Patent prints

visible prints

Laten prints

invisible prints

Plastic prints

3D prints in soft material (e.g., clay, wax)

What are the 2 main categories of fingerprints?

Known & Unknown fingerprints

Known prints

inked and live scan prints

Unknown prints

full or partial prints found at scene of crime

AFIS sytsem

uses AFIX

Automated Fingerprint Identification System

3 main prints pattern:

1. Arch

2. Loop

3. Whorl

Porous surfaces

has holes were air or water could pass through

(e.g., paper, cardboard, or cloth)

Non-porous surfaces

no holes

(e.g., glass, meal, tile)

Powder types

1. Magnetic powder

2. Volcanic powder

Brush Types

1. Animal hair

2. Feather

3. Synthetic

4. Fiberglass

5. Magnetic

Nonporous processing

1. Cyanoacrylate fuming (Superglue fuming) & Rhodamine 6G (R6G)

2. Fluorescent powders

Gentain Violet (GV) (tape processing)

purple dye stain which adheres to cells left behind

Powder in suspension (tape processing)

fingerprint powder suspended in reagent

1. WetWop: black or white

2. Sticky side powder: equal parts water, photoflo, & volcanic powder in color with maximum contrast

Iodine processing via sublimation

non-destructive technique

1,2 Indanedione (Indy)

reacts with amino acids

• processed with heat

• viewed under ALS

Ninhydrin (Ruhemann’s purple)

reacts with Alpha Amino Acids

• can react to blood & saliva

• most common

• most destructive

Compressed

produce smaller image files to allow more space

(e.g., JPEG)

Uncompressed

no pixel values are lost (TIFF)

All photographs of latent prints be taken at

100 PPI, grey scale, and in lossless file format

NIST

National Institute of Standards and Technology