Fingerprint Characteristics and Types

Fingerprint Characteristics

• Fingerprints develop during fetal development at approximately 10 weeks of pregnancy.
• Dermal ridges are the raised portions of a fingerprint, arranged in connected units for enhanced grip.
• Minutiae are the ridge characteristics that distinguish each fingerprint and make it unique.

Fingerprint Types

• Arches (5%): Ridges enter on one side and exit the other; can have one delta. Subtypes include plain and tented arches.
• Loops (65%): Ridges enter on one side and exit on the same side, with one delta. Subtypes include ulnar loops (tail points towards the pinky finger) and radial loops (tail points towards the thumb).
• Whorls (30%): Have a circular or spiral pattern with two deltas. Subtypes include plain, central pocket, double-loop, and combination whorls.

Fingerprint Types (detailed info)

• Core: Center of a loop or whorl
• Delta: Triangular regions near a loop or whorl
• Ridge count: The number of ridges counted from the core to the edge of a delta.

Types of Prints

• Patent prints: Visible prints transferred onto a smooth surface by a liquid (e.g., a bloody print).
• Latent prints: Invisible prints that need techniques to visualize, like dusting or chemicals (e.g., fingerprints found on a coffee mug).
• Impression prints: Indentations left in soft materials like wax or soap (e.g., an imprint in a soap bar).

Fingerprint Databases

• AFIS (Automated Fingerprint Index System): A large FBI database used to identify fingerprints.

Latent Print Development Techniques

• Black powder: Used on hard, non-absorbent, light-colored surfaces. Use a fluffy brush and twirl over the area, then lift with transparent tape.
• Fluorescent powder: Used on hard, non-absorbent dark-colored surfaces. Use a magnetic wand to apply and lift the magnetic powder.
• Cyanoacrylate: Used on household items (metals, glass, skin). Vaporizes to reveal prints when left in a closed container.
• Ninhydrin: Used on paper or cardboard; reveals a pink/purple reaction.
• Silver Nitrate: Used on wood or Styrofoam.
• Iodine fuming: Used on paper, cardboard, or unpainted surfaces; reveals a yellow reaction. Use in a closed container for vaporization.

Explore the fascinating world of fingerprint characteristics and types. This quiz covers the development of fingerprints, specific minutiae that make each print unique, and the different types of fingerprint patterns including arches, loops, and whorls. Test your knowledge on this essential topic in forensic science!