Fingerprint Types and Impressions

Types of Fingerprint Impressions

• Three types: latent, patent, and plastic.

Patent Fingerprints

• Liquid impressions observed on surfaces, such as blood or ink.

Plastic Fingerprints

• Actual indentations found in soft materials, like clay or wax.

Latent Fingerprints

• Hidden prints resulting from the transfer of oils and secretions onto surfaces.

Fingerprint Powders

• Common types include grey, black, magnetic, and fluorescent powders.

Fingerprint Chemicals

• Include ninhydrin, physical developer, cyanoacrylate fuming, iodine fuming, crystal/gentian violet, amido black, and LCV.

Ninhydrin

• Reacts with amino acids in sweat to produce purple-blue prints.

Physical Developer

• Liquid silver nitrate, used as a last resort because it destroys proteins.

Cyanoacrylate (Superglue) Fuming

• Developed by Japanese police in 1982, useful for fingerprint development.

Iodine Fuming

• An older method where vapors react with fatty oils and sweat.

Crystal/Gentian Violet

• Utilized for developing tape prints.

LCV (Leuco Crystal Violet)

• Effective for enhancing faint bloody prints.

Amido Black

• A stain for enhancing faint bloody prints.

Preserving Latent Prints

• Methods include photographing, covering, and lifting prints with tape to a labeled card.

Composition of Fingerprints

• Composed mainly of sweat (99-99.5% water) and contaminants (body fluids, oils).

Factors Affecting Fingerprints

• Influence of age, ridge structure, stimuli, medical conditions, and environmental factors.

Transposal Factors

• Include surface texture, hand contaminants, receiving surface, contact, and pressure.

Environmental Factors

• Conditions such as temperature, humidity, and handling affect fingerprints.

Limitations of Fingerprints

• Cannot solely determine a person's age, sex, or race.

Uses of Fingerprints

• In crime solving, identity confirmation, deceased identification, access control, and employment clearances.

Fingerprint Printing Order

• Right thumb, pointer, middle, ring, pinky, followed by the left hand in the same order.

Factors Affecting Good Fingerprints

• Self-printing habits, excessive pressure, wet fingers, and health issues.

Supplies for Taking Prints

• Requires an ink pad, ten-print card, adequate space, and hand soap.

Steps to Taking Fingerprints

• Communicate, roll prints, take plain impressions, and clean up afterward.

Special Situations in Fingerprinting

• Consider issues such as amputations, bandaged fingers, scars, and deformities.

Definition of Fingerprint

• An impression made by a finger's friction ridges upon contact, unique to each individual.

Fingerprint Patterns

• Arches: extends from one side to the other.
• Loops: enter and exit from the same side.
• Whorls: circular patterns.

Ridgeology

• The study focused on the uniqueness of friction ridge structures for personal identification.

Classification System

• Similar to alphabets, each fingerprint pattern is assigned a specific value for identification.

Invisible Fingerprints

• Created by deposits of oil and perspiration, requiring development to become visible.

Iodine Method Effectiveness

• Particularly good for lifting prints with fat or oil residue.

Friction Ridge Formation

• Established at birth and unchanged thereafter.

Alphonse Bertillon's Contribution

• Noted for using fingerprints to help identify lost children.

Key Case for Fingerprint Evidence

• "People v. Jennings" (1911) established the admissibility of fingerprint evidence.

Lifting Fingerprints

• Typically lifted using clear cellophane tape.

Forensic Conclusions from Latent Prints

• Can determine the identity of the perpetrator based solely on latent prints.

Dactylography

• The study of fingerprints as a method of identification.

Patterns of Fingerprints

• Classified into arched, looped, and whorled patterns.

Chemical Methods for Development

• Four distinct chemical methods exist for developing fingerprints on various surfaces.

Types of Fingerprints

• Patent fingerprints are visible, made by blood or other substances.
• Latent fingerprints are not immediately visible and require development techniques.