Integumentary System and Forensic Fingerprint Examination

Comprehensive vocabulary flashcards covering the integumentary system, friction ridge formation and anatomy, deposition factors, surface types, pattern classifications, minutiae, physical and chemical development methods, levels of detail, and the ACE-V framework based on Week 5 lecture notes.

Integumentary system

The organ system consisting of the skin and associated structures, including hair, nails, sweat glands, and sebaceous glands, that functions in protection, temperature regulation, sensation, and water loss prevention.

Epidermis

The outermost layer of keratinised stratified squamous epithelium that acts as a protective barrier and contains surface friction ridges.

Dermis

The layer of connective tissue beneath the epidermis containing blood vessels, nerves, sweat glands, and collagen that supports and nourishes the epidermis while providing sensation and strength.

Hypodermis

The subcutaneous layer of adipose and connective tissue located beneath the skin proper that provides insulation, cushioning, and energy storage.

Friction ridges

Raised epidermal structures found on the fingers, palms, toes, and soles of the feet that improve grip, support tactile sensation, and form distinctive patterns.

Fingerprint

An impression or deposit left on a surface produced when material from the skin is transferred, or when the skin deforms a soft material.

Eccrine sweat

Glandular secretions consisting of water, salts, amino acids, urea, and lactate, produced by glands abundant on friction ridge skin and targeted by chemical detection methods.

Sebaceous secretions

Secretions containing lipids, fatty acids, wax esters, and squalene that can improve fingerprint powder adhesion and are transferred to friction ridges by touching the face or hair.

Porous surfaces

Substrates such as paper, cardboard, and untreated wood that absorb fingerprint residues into their internal structure.

Non-porous surfaces

Substrates such as glass, metal, and smooth plastic where deposited fingerprint residues generally remain on the exterior surface.

Semi-porous surfaces

Substrates exhibiting both porous and non-porous characteristics, such as glossy cardboard, coated paper, and certain painted surfaces.

Patent fingerprint

A visible fingerprint impression formed through the transfer of a coloured substance, such as blood, ink, or paint.

Latent fingerprint

A usually invisible or difficult-to-see fingerprint impression formed from transferred natural skin residues such as sweat and lipids.

Plastic fingerprint

A three-dimensional fingerprint impression formed when friction ridges press into a soft, deformable material such as wax or putty.

Level 1 detail

The overall ridge flow and general pattern configuration (loops, whorls, and arches) used for classification and exclusion, but insufficient on its own for individual identification.

Level 2 detail

Specific friction ridge minutiae, such as ridge endings and bifurcations, including their relative positions and spatial orientations used to support individualisation.

Level 3 detail

Fine ridge structures, including pore positions, pore shapes, ridge edge contours, and fine ridge imperfections or scars.

Delta

A triangular or triradial region within a fingerprint pattern where ridge flows diverge.

Core

The approximate central area of a fingerprint pattern.

Loop

A fingerprint pattern in which ridges enter, recurve, and exit from the same side, typically containing $1$ delta; it represents approximately $62.5\%$ (range $60\text{--}65\%$) of all patterns.

Ulnar loop

A loop pattern whose ridges open towards the little-finger side of the hand.

Radial loop

A loop pattern whose ridges open towards the thumb side of the hand.

Whorl

A fingerprint pattern featuring circular or spiral ridge formations, usually containing $2$ deltas; it represents approximately $32.5\%$ (range $30\text{--}35\%$) of all patterns.

Plain whorl

A whorl pattern in which at least one ridge completes a full circuit, with $2$ deltas present.

Central pocket loop whorl

A fingerprint pattern consisting of a whorl-like central circuit surrounded by looping ridges, distinguished by its delta and line-of-contact relationship.

Double loop whorl

A fingerprint pattern consisting of two distinct loop formations within the same overall pattern.

Accidental whorl

A complex fingerprint pattern combining features of different pattern types that does not conform to plain, central pocket loop, or double loop whorl categories.

Arch

A fingerprint pattern whose ridges enter from one side, rise in the centre, and exit the opposite side, usually lacking deltas; it represents approximately $5\%$ of all patterns.

Plain arch

An arch pattern where ridges enter on one side, rise gently in the centre, and flow out the opposite side.

Tented arch

An arch pattern characterized by ridges that form a sharp rise, upthrust, or tent-like configuration in the centre.

Minutiae

Small, distinctive local ridge characteristics, such as ridge endings and bifurcations, used in forensic comparisons to establish correspondence between impressions.

Ridge ending

A minutia feature where a friction ridge terminates abruptly.

Bifurcation

A minutia feature where a single friction ridge divides into two separate branches.

Island (short ridge)

A minutia feature consisting of a short, isolated friction ridge segment.

Dot

A minutia feature consisting of a very small, isolated ridge feature.

Bridge

A minutia feature where a short ridge connects two longer adjacent ridges.

Spur

A minutia feature consisting of a short branch extending off from a longer ridge.

Eye (enclosure)

A minutia feature where a ridge divides and subsequently reconnects, enclosing an open space.

Trifurcation

A minutia feature where a single ridge divides into three separate branches.

Conventional fingerprint powders

Fine particles (black, white, grey, or metallic) that adhere mechanically to friction ridge residues on smooth, dry, non-porous surfaces.

Fluorescent powders

Particulate powders that adhere to fingerprint residues and emit visible light under specific wavelengths of illumination, providing contrast on multicoloured backgrounds.

Magnetic powders

Powders applied using a magnetic applicator rather than a standard brush, minimizing mechanical damage to delicate latent impressions on smooth, non-porous surfaces.

Iodine fuming

A chemical method where heated iodine crystals produce vapour that is absorbed by lipid residues on porous or non-porous surfaces, producing a temporary reddish-brown pattern.

Cyanoacrylate fuming

A chemical process, also known as superglue fuming, where cyanoacrylate vapour polymerises on fingerprint residues on non-porous substrates to produce a stable white deposit.

Ninhydrin

A chemical reagent that reacts with amino acids in fingerprint residue on porous surfaces to produce a purple-coloured product known as Ruhemann's purple, optimal at approximately $26\text{--}38^\circ\text{C}$.

Small Particle Reagent (SPR)

A liquid suspension of fine particles (such as molybdenum disulfide or zinc carbonate) in detergent that adheres to the lipid components of fingerprint residues on wet, non-porous surfaces.

Vacuum Metal Deposition (VMD)

A sensitive thermal evaporation technique under vacuum involving the sequential deposition of gold and zinc to create visual contrast on non-metallic and difficult substrates.

ACE-V

A structured forensic friction ridge examination framework representing Analysis, Comparison, Evaluation, and Verification.