1. Classification of Fingerprints

2. AFIS Automated Fingerprint Identification System
Fingers are scanned to a screen where they can be enhanced and identified.
In 2007 the FBI had more than 55 million digital fingerprints of known criminals.

4. AFIS Criminal courts consider 12 points a “match” for prints
Known Print on File
Unknown Print

5. Types of Prints Plastic (Molded) Print
3D print made as indentations in soft material
Examples : fresh paint, soap, candle wax

6. Types of Prints Visible Print
left by a finger that has touched colored material
Examples: blood, paint, ink, grease, mud

7. Types of Prints Latent Print
prints result from deposit of secretions from skin
invisible to the naked eye until developed
developed by chemical or physical means

8. Visualizing Latent Prints
Powders
used on hard, nonabsorbent surfaces
adhere to both water and fatty deposits
choose a color to contrast with the background

9. Visualizing Latent Prints
Iodine
fumes react with oils and fats to produce a temporary yellow-brown color
works best developing fingerprints on paper or cardboard

10. Visualizing Latent Prints
Ninhydrin
fumes reacts with amino acids to produce a purple color
works best developing fingerprints on porous surfaces such as paper, wood, cardboard

11. Visualizing Latent Prints
Cyanoacrylate
“superglue” fumes react with water and other fingerprint constituents to form a hard, whitish deposit.
works best on developing fingerprints on hard nonporous surfaces such as metals, glass, and plastic