Question

name: date: period: 1. explain the difference between patent, latent, and plastic fingerprints. 2. how do environmental factors affect the visibility of latent fingerprints? 3. draw and label the three main fingerprint patterns: loop, whorl, and arch. 4. describe how fingerprint patterns are formed during fetal development. 5. what are minutiae points and how are they used in fingerprint comparison? 6. draw a fingerprint and label the core, delta, and ridge count. 7. explain how afis (automated fingerprint identification system) works.

Explanation:

1. Patent fingerprints are visible to the naked - eye, left by substances like ink or blood. Latent fingerprints are invisible and require special techniques (e.g., powder dusting, chemical development) to make them visible. Plastic fingerprints are three - dimensional impressions left in soft materials like putty or wax.
2. Environmental factors such as humidity, temperature, and surface type affect latent fingerprint visibility. High humidity can cause the ridges to swell or the deposited substances to dissolve. High temperatures can accelerate the decomposition of the substances in the fingerprint. Porous surfaces like paper absorb the fingerprint residue, while non - porous surfaces like glass can hold the residue better for detection.
3. A loop has one or more ridges that enter from one side, curve around, and exit from the same side. A whorl has at least one ridge that makes a complete circuit, and may have two deltas. An arch has ridges that slope upward and then down without making a loop or a circuit.
4. Fingerprint patterns are formed during the second and third trimesters of fetal development due to the interaction between the basal layer of the epidermis and the dermal papillae. The pressure and growth patterns create the unique ridge patterns.
5. Minutiae points are the small details in a fingerprint such as ridge bifurcations (where a ridge splits into two) and ridge endings (where a ridge stops). In fingerprint comparison, these points are used to match two fingerprints. If a sufficient number of minutiae points match in terms of type, location, and orientation, the fingerprints are considered a match.
6. The core is the approximate center of the fingerprint pattern. The delta is a triangular - shaped area where three ridge systems meet. Ridge count is the number of ridges between the core and the delta.
7. AFIS works by first scanning a fingerprint to create a digital image. Then, it extracts the minutiae points from the image. These minutiae points are then compared to a database of stored fingerprint minutiae. If a sufficient number of matches are found, the system identifies the fingerprint.

Answer:

1. Patent fingerprints are visible, latent are invisible and need special detection, plastic are 3 - D impressions.
2. Humidity, temperature, and surface type affect visibility. High humidity can dissolve residue, high temperature can decompose it, and non - porous surfaces are better for detection.
3. Loop: ridges enter and exit from same side; Whorl: has a complete circuit and may have two deltas; Arch: ridges slope up and down without loop or circuit.
4. Formed in 2nd - 3rd trimesters due to interaction between epidermis and dermal papillae.
5. Minutiae are small details like bifurcations and endings, used to match fingerprints by comparing type, location, and orientation.
6. Core is center, delta is triangular area where 3 ridge systems meet, ridge count is between core and delta.
7. Scans fingerprint, extracts minutiae, compares to database for identification.