Fingerprint Analysis and Identification

Fingerprint Expert Introduction

Jen, a fingerprint expert with the South Australia Police for nine years, works at the Forensic Science Centre in Divot Place. She discovered the job through government advertisements while studying criminology and criminal justice. The role involves internal and external training, with a five-year traineeship. Internal training covers procedures, while external training involves a diploma, advanced diploma, and graduate certificate in forensic investigation and fingerprint investigation from the Cambria Institute of Technology. The fifth year focuses on honing skills, understanding procedures, and fingerprint proficiency.

Expert Examination

After five years and meeting training requirements, trainees undertake an expert's exam, including two written exams on learned topics, a latent exam requiring 100% accuracy on 100 latents over five days, and a mock court. The mock court involves producing and presenting a court case in a simulated setting, preparing for real court evidence presentation.

General Overview of Fingerprints

The lecture provides a general overview of fingerprints, their nuances, and the reasons for the extensive five-year training period. It aims to give a taster of the various aspects of fingerprint analysis.

Definition of a Fingerprint

In court, a fingerprint is defined as a reproduction of the pattern of friction ridge skin on palmar (palms and fingers) and plantar surfaces (soles of feet and toes). Jurors are encouraged to examine their fingertips to observe friction ridge skin patterns and unique characteristics such as abrupt stops or bifurcations, which are used for identification.

Fundamental Principles of Fingerprint Science

  1. Uniqueness and Variability: Friction ridges are highly variable, with characteristics not duplicated in other regions of the same person or in different individuals. This principle underscores the uniqueness of fingerprints.

  2. Permanence and Unchanging Nature: Configurations and characteristics are permanent from before birth until decomposition, highlighting the persistence of friction ridge skin patterns throughout life.

  3. Systematic Classification: Configuration types vary within limits, enabling systematic classification, particularly important when technology was limited and manual classification was necessary.

Function of the Skin

The skin, the largest organ, protects vital organs, acts as a barrier to infection, and regulates body temperature. Friction ridge skin differs from normal skin by being corrugated in nature, found only on palmar and plantar surfaces, and assisting in grip. It lacks hair follicles.

Development of Fingerprints

Fingerprint development begins in utero: Volar pads develop at seven to eight weeks, followed by friction ridges at ten and a half weeks. Ridges form around the greatest topographical change on volar pads, determining fingerprint patterns. High pads create whorl patterns, skewed pads create loop patterns, and low pads create arch patterns.

Genetics, environmental factors, maternal drug use, and womb pressure influence fingerprint characteristics. Even identical twins have different fingerprints due to varied pressures and movements in the womb.

As the fetus grows, the epidermis connects to the dermis, forming primary and secondary ridges. Friction ridge skin contains only one set of glands.

Structure of Friction Ridge Skin

The structure includes the epidermis, pore openings, sweat glands, and dermal papillae, which provide strength between the epidermis and dermis. This structure is relevant in understanding decomposition processes.

Glands of the Skin

  1. Eccrine Glands: Found on palmar and plantar surfaces, secreting mostly water with inorganic and organic compounds like amino acids, important for chemical development.

  2. Sebaceous Glands: Associated with hair follicles, producing sebum, a thick, viscous secretion that is more stable on surfaces.

  3. Apocrine Glands: Piggyback off sebaceous glands, found in armpits and anogenital areas, becoming active during puberty and producing scent.

Fingerprint deposits typically contain a combination of all three secretions due to frequent facial contact.

History of Fingerprints

  • Paris Palmitis (2000 years ago): Marcus Fabius Quintilianus used a palm print on a wall to defend a blind boy accused of patricide, arguing the print was too large and high for the boy, leading to the stepmother's confession.

  • Johannes Perkinje: First to classify and name fingerprint patterns, with his Spanish descriptions forming the basis of many English translations used today.

  • Henry Folds: A medical missionary in Japan, Folds observed fingerprints in washed-up pottery and conducted experiments proving their persistence. He advocated for their use in crime investigation, using them to match a greasy print to a moonshine producer and acquit a suspect in a hospital lab break-in.

  • Francis Galton: Cousin of Charles Darwin, Galton estimated the probability of two people having the same fingerprints at one in 64 billion. He wrote the first text on fingerprints in 1892 and described characteristics known as Galton details.

  • William Herschel: Famous for persistency tests, Herschel printed himself throughout his lifetime, demonstrating that fingerprint characteristics remained unchanged despite aging.

  • Alfonso Berthian: Used anthropometry, measuring 11 body dimensions for identification, supplemented with thumbprints. The system was widely adopted until a case involving William West and Will West, who had the same measurements but different fingerprints, discredited it.

  • Juan Visatich: Established the first fingerprint bureau in La Plata, Argentina, and developed a classification system still used in some Spanish-speaking countries. He is credited with the first recorded identification of a person via fingerprints in a double child murder case, leading to the mother's confession.

  • Edward Henry: Developed a robust classification system with Abdul Haig and Chandra Bose, detailed in his textbook Classification and Uses of Fingerprints. The Henry classification system is still used today for older sets of prints.

Fingerprint Bureaus in Australia

South Australia opened its first fingerprint bureau in 1904.

Fingerprint Investigation and Analysis

  1. Surface Type Consideration

    • Porous Surfaces: Paper, cardboard, fabric, untreated wood (absorb fingerprint deposits).

    • Semi-Porous Surfaces: Wax surfaces, varnished wood (slowly absorb deposits).

    • Non-Porous Surfaces: Plastics, glass, weapons (deposits sit on top, easily wiped off).

  2. Poor Surfaces: Weathered or dirty objects, polymer banknotes, rusty or weathered items, human skin (difficult to obtain prints), chipboard, and highly textured surfaces.

  3. Triaging Exhibits: Consider surface suitability, deposit composition (blood, etc.), and potential DNA analysis to avoid destroying evidence.

Sequence of Treatment

  1. Optical Techniques: Using natural light and oblique lighting to visualize prints.

  2. Physical Development: Powders (white, black, aluminum, magnetic, fluorescent) to enhance contrast.

  3. Chemical Development: Using chemicals to react with fingerprint constituents (amino acids). This method is more destructive.

Powders

  • White and Black Powders: Create contrast on dark or light backgrounds, respectively.

  • Aluminum Powder: Used on various colored surfaces.

  • Magnetic Powder: Used on porous items like paper.

  • Fluorescent Powder: Used on multicolored surfaces, viewed under UV light to eliminate background interference.

Chemical Development

  • Ninhydrin: Reacts with amino acids in eccrine secretions, developing a purple color on porous items like paper and cardboard. Effective on prints up to a century old.

  • Indandione: A contemporary, quicker version of ninhydrin, used on paper, with heat as a catalyst. It fluoresces under laser light.

  • Cyanoacrylate Fuming (Super Glue Method): Reacts with moisture from latent deposits on non-porous items. Items are placed in a super glue chamber, heated, and then treated with a fluorescent dye (Ardrox) and viewed under UV light.

  • Amido Black: Reacts with protein in blood on exhibits like knives, developing a dark blue color. It is a destructive process and cannot be used if DNA analysis is needed.

Kapunda Murders Case Study: Amido Black was used to develop a fingerprint on a door, leading to Jason Downey's confession after matching his prints, which he had no reason to be there.

Other Chemical Treatments: A range of chemicals for various reasons, the textbook includes details on these treatments.

Fingerprinting Deceased

Fingerprinting assists in identifying deceased individuals, especially those not visually identifiable due to decomposition or fatal accidents. This is done for murders and deaths in custody.

  • Recently Deceased: Generally, in a good, fresh deceased condition.

  • Early Decomposition: The epidermis starts to release from the dermis, requiring careful handling.

  • Advanced Decomposition: Putrefied, waterlogged (maceration), desiccated/mummified, charred, or burnt remains present extra challenges.

Methods for Fingerprinting Deceased

  • Mortuary Spoon: A modified shoehorn is used to cradle the finger and obtain good fingerprints.

  • Dermal Identification: The dermal layer replicates the ridges when the epidermis is removed, appearing as tram tracks.

  • Macerated Remains: The epidermal layer comes away from the dermis, with grayish skin coloring.

  • Cast Method (Aquadere Method): Used for mummified/desiccated fingers, using Microsil or aquadere to create a fingerprint negative.

  • Gloving: Plumping out finger skin with one's finger to photograph or print when the epidermal layer comes off.

NAFIS (National Automated Fingerprint Identification System)

Technology used since 1996, upgraded in 2000 to include palm prints. Live scan images capture fingerprints digitally. The system uses an algorithm to distinguish pattern types and characteristics, stored in 10-print and unsolved latent databases. New prints are searched against latent prints from crime scenes. Candidates are manually checked, comparing a list of at least 30 candidates (not automatically identified).

  • Statistics:

    • Over 10,000,000 registration events.

    • Over 6,000,000 individuals on the system.

    • Over a million unsolved latents.

Fingerprint Identification Process

Fingerprints are categorized into arches, loops, and whorls. To make an identification, the pattern types must match, and there must be consistent ridge flow. Ridge characteristics (ridge endings, bifurcations) must be in the same relative position and have the same number of intervening ridges.

Clarity and a sufficient number of characteristics are needed. No unexplainable dissimilarities should be present. Distortions can occur due to skin pliability, but dissimilarities must be justifiable.

ASV Methodology

The process involves Analysis, Comparison, Evaluation, and Verification. It consists of the following steps:

  1. Analysis: Examine the unknown print for suitability, clarity, and minutiae.

  2. Comparison: Compare the unknown print to a known set of prints.

    • Three Levels of Comparison:

      • Pattern type matching.

      • Minutiae and characteristics.

      • Pore location and shape, ridge edges (used if clarity is sufficient).

  3. Evaluation: Determine if the print is identified to the person.

  4. Verification: A peer review process to reduce errors, with at least three people verifying each identification.

WordMate

WordMate is a program used to compare two images side by side. On the left, is the crime scene images, and on the right, the 10-print form. Green and orange are used to identify the images being compared. They compare and match the ridges in both of the images.

Damage and Mutilation

Damaging or mutilating fingerprints does often avoid detection. Damaging the epidermal layer results in temporary changes as the skin regenerates. Dermal layer damage creates scars that may cause puckering, complicating identification.

Roscoe Pitts: An American gangster who had friction ridge skin removed from his fingertips and grafted smooth skin from under his armpits. Although the fingertips were smooth, other areas of his friction ridge skin still allowed identification.
Mutilation Examples: Cutting the friction is another attempt to damaging the skin, some used acide, and some used superglue but all in all gloves is the easiest prevention method.

Conclusion

Fingerprint analysis is robust, reliable, and invaluable in forensic investigation, with over a hundred years of experience and continues to improve.