Introduction to Fingerprint Identification

Fingerprints introduction Start by printing your own prints on a cue card. Do each finger. Consider the following questions: – What do you notice about the types of fingerprints? Are the general patterns? Do all of your fingerprints have the same pattern? Can you categorize patterns looking at yours, and some prints from people sitting next to you? Any fine features stand out? – How do you think fingerprints are formed on your hands? What is their function? Do other animals have fingerprints? How are they transferred to other objects (i.e. what is being transferred? Why do your fingers leave prints?)

What We’ll Cover A Brief History – See Timeline How Fingerprints Are Formed Types of Prints and Minutiae – Loops, Whorls and Arches Methods of Detecting, Visualizing and Lifting Prints Databases The Admissibility of Fingerprints

History

Alphonse Bertillon 1883 Created the first systematic system of individual classification & identification Detailed description of subject, full-length & profile photographs & a system of precise body measurements (anthropometry)

Sir Francis Galton Sir Francis Galton, a cousin of Charles Darwin, began his observations of fingerprints in the 1880's. In 1892, he published "Fingerprints", Fingerprints do not change over the course of an individual's lifetime, and that no two fingerprints are exactly the same According to his calculations, the odds of two individual fingerprints being the same were 1 in 64 billion.

Will West 1903: William West incident – Fort Leavenworth prison – New prisoner William West couldn’t be distinguished from unrelated inmate with same name by anthropometry – Discovered that their fingerprints differed

How Fingerprints Are Formed

Fingerprints A fingerprint is an INDIVIDUAL CHARACTERISTIC – Fingerprints are made by genes as well as the environment – Form during 1 st 3 months of life – Do not change over the course of your life, although they may be altered or scarred They evolved in some primates and other animals (e.g. koalas) for firmer grasp and resistance to slippage They are comprised of a series of lines

Efforts to Remove Fingerprints are Unsuccessful See the article on Dillinger

Anatomy of the Fingerprint Skin has layers: Epidermis (outer portion) and dermis (inner portion) Between these layers is the ‘dermal pappillae’ where fingerprints form Sweat glands secrete perspiration to the surface of the skin – sweat is vital to the formation of latent fingerprints

Latent Prints There are 2 types of sweat glands – only those found on the surfaces of the hands and feet (eccrine glands) secrete perspiration that does not contain oil Oil in fingerprints comes from the hand contacting other parts of the body (e.g. face) or other substances containing oil – When the finger comes into contact with another surface, the water and dissolved substances are transferred – This leaves an impression of the finger’s ridge pattern (fingerprint) – These are typically invisible to the eye and referred to as latent fingerprints

Types of Prints and Minutiae

Types of Prints

FINGERPRINTS HAVE GENERAL RIDGE PATTERNS FOR CLASSIFICATION: Divided into three classes: – LOOP – WHORL – ARCH 60-65% OF THE POPULATION HAS LOOPS 30-35% WHORLS AND 5% ARCHES

Minutiae

Making Comparisons There can be up to 150 identifiable features on each print Most prints recovered from crime scenes are partial impressions Courts usually require 8-16 matching characteristics, but often this number is not as important as the expertise of the fingerprint examiner

Loops A loop must have one or more ridges entering from one side of the print, recurring and exiting from the same side.

Whorls All whorl patterns must have type lines and a minimum of two deltas.

Plain Whorl In this plain whorl, the line between deltas touches and runs through the central pattern

Central Pocket Whorl In this central pocket whorl, the line between the deltas does not touch any ridge formation in the inner part of the pattern.

Double Loops and Accidental The DOUBLE LOOP is made up of any two loops combined into one fingerprint. Any print classified as ACCIDENTAL either contains two or more patterns (not including the plain arch) or the pattern is not covered by other categories i.e., a combination loop and a plain whorl or a loop and tented arch.

Arches Of the two types of arches, the PLAIN ARCH is the simplest of all fingerprint patterns. It is formed by ridges entering from one side of the print and exiting on the opposite side. These ridges tend to rise at the center of the pattern, forming a wavelike structure. The TENTED ARCH is similar, but instead of rising smoothly at the center, there is either a sharp up thrust or spike,

Revisit your prints Using the knowledge you now have about fingerprints and their classification, go back and look at all of your prints and describe them

Crime scene identification Add your prints to the samples from the whole class After the teacher has photocopied the class set and completed the presentation use the skills you have learned to try to identify the suspect’s print

Test Your Knowledge Use the fingerprint Cut Match and Paste sheet to test your skills at identifying types of fingerprints Complete the Fundamental Principles of Fingerprints sheet

Methods of Detection

Fingerprint visibility Latent fingerprint- earlier stated was invisible to the eye since they are just perspiration and sometimes oil. – Composed mainly of water (95%) and 5% other substances – chemicals used to make these visible react with some of these substances – Latent prints are more difficult and require use of technologies and techniques that will make the print visible. Visible Prints: made by fingers touching a surface after ridges have been in contact with colored material: BLOOD, PAINT, GREASE, INK Plastic Prints are ridge impressions left in soft material- putty, wax, soap, or dust.

METHODS OF DETECTING LATENT FINGERPRINTS THE METHOD OF CHOICE WILL DEPEND ON THE SURFACE BEING LIFTED OR TESTED. Hard and non-absorbent surfaces (glass, mirror, tile, and painted wood) require different approaches than soft and porous- paper, cloth, or cardboard. The most challenging thing an examiner faces is location of latent prints.

Visualization of Latent Prints On hard surfaces: – Powder Grey or black or white Florescent Magnetic – Superglue – Lighting Techniques Complete latent print lifting using the corn flour and the mirror or glass

Ultraviolet Imaging Systems Latent fingerprint on Painted Wall. Illustration of Contrast Effect due to variation of illumination angle. Depending on what angle the user holds the light, a print can either appear white or black. Untreated Oily Print on sticky side of Duct (Duck) tape. 35mm Black and White film. Scene Scope excels at detecting prints on surfaces that a forensic light source would find difficult or impossible.

Ultraviolet Imaging Systems Hand held Forensic Light Sources

Fingerprint Powders Commercially available in a variety of colors and textures (photographing) Lightly applied to nonabsorbent surfaces with camelhair brush will ADHERE TO PERSPIRATION RESIDUES AND BODY OILS. Black and gray for photographing on surfaces- produce contrast.

Test Your Knowledge Complete the Kinds of Fingerprints found at crime scenes sheet

Admissibility

Fingerprints and their use in court The low probability of 2 unrelated prints matching is the foundation for its acceptance in court – Recall Galton said the probability that two fingerprints could match is one in 64 billion. – This is supported by the millions of individuals who have had prints taken over the past 90 years in the FBI central system- no two have ever been found to be identical

Removing Prints from the scene Sometimes criminals try to remove prints from weapons or the scene after they commit a crime See article on Fingerprint Breakthrough