Friction Ridge Skin

Comparison and Identification of Fingerprints

James F. Cowger

• Publisher: CRC Press
• Year: 2020
• ISBN:
  9781000151787
• Edition: 1
• Topic: Architecture
• Subtopic: Architecture General

Here is a complete guide to the collection, classification, and comparison of friction skin prints and the determination of identity and nonidentity. It discusses: the cause and significance of variations in prints; the importance of class characteristics in print; the application of probability in decision making; and photographic techniques and considerations.

Introduction

1

Covering the palmar surfaces of the hands and the plantar surfaces of the feet is friction ridged skin (Figure 1.1). Of all the attributes of humankind, this friction skin is the only one that is currently capable of individualization to the extent that it is possible, within practical limits, to say that no two people are alike. That such is the case is accepted today as fact even by those who have no knowledge of how the friction skin of two individuals differ.

Friction ridges form on the hands and feet of a fetus before birth; barring injury (Figure 1.2), their form does not change during life. These ridges are not continuous parallel lines, but have endings and bifurcations (points where a ridge divides into two ridges). A ridge may be quite short and may be so short as to appear as a dot. It is the orientation, location, and interrelationship of these features in the coursing of the friction ridges that makes it possible to determine whether two prints were made by the same individual.

That the arrangement of these minutiae is sufficiently different on each finger, palm, toe, and sole that every individual can be considered unique has been validated by decades of work by thousands of examiners. There has yet to be reported an instance of two prints being so similar that their donors could not be differentiated. This does not prove that no two such prints will ever be found; it does, however, indicate that the probability of such an occurrence is infinitessimally small, and can be considered nonexistent for practical purposes.

Although many decades of experience by dedicated workers may seem sufficient to support the individuality of friction skin, many have attempted to demonstrate its individuality using calculations of probability. The first such calculation was published in the landmark treatise Finger Prints (Galton, 1892) and stated that the probability of duplication of an entire fingerprint was .25. More recently, the probability of the occurrence of but a portion of a fingerprint has been calculated to be 10⁻²⁰ (Osterburg et al., 1977). The probability of duplication, based on this figure, is substantially greater given the extent of each individual fingerprint and the fact that almost everyone has 10 fingers. Thus, the mathematical and empirical (experiential) data are more than adequate to provide a very sound basis for the use of friction skin prints as a means of positive, certain identification.

Figure 1.1 An inked fingerprint and the finger that made it.

A number of researchers have shown that the patterns in friction ridged skin are affected by genetic factors (Srivastava, 1965; Mukherjee, 1966; Holt, 1968). These patterns are the general flows of the friction ridges. There is as yet no evidence that the arrangement of the minutiae (ending ridges, bifurcating ridges, etc.) is in any way genetically influenced. Even in cases of very close kinship, such as identical (monozygotic) twins the prints of the individuals are still easily distinguished by comparison of the minutiae, although the pattern types may be quite similar. Prenatal illness, however, can affect fingerprints, causing what is known as dissociation of the ridges: disrupted ridge flows and dotted, rather than continuous, ridges (Figure 1.3).

Friction ridged skin is a highly specialized organ and differs from the skin on the rest of the body in more than simply its ridged appearance. It has no hair follicles and, thus, no apocrine or sebaceous glands. These papillary ridges are orderly rows of eccrine (sweat) glands which are distributed in excess of 400/cm²; the average distribution over the rest of the skin surface averages but 130/cm². Friction ridged skin is also thicker than other skin and contains more nerve endings than other parts of the body (Montagna, 1956).

Figure 1.2 The effects of scarring.

Friction ridges for traction, thicker skin for protection from injury, no sebaceous glands to secrete waxy, oily sebum, no hair to come between the skin and what is grasped or trod, and a heightened sense of touch makes friction skin ideal as a covering for palms and soles. Fortunately, the arrangement of the friction ridges also makes it ideal as a means of determining identity.

Although humans were undoubtedly long aware of the existence of the friction ridges on their hands and feet, the earliest written reference to friction skin is a paper by Dr. Nehemiah Grew (1684) delivered to the Royal Society in London. In the paper Grew reported on the patterning of the fingers and palms, and commented on the arrangement of the sweat pores along the ridges. He did not deal with the individuality of friction skin and it seems certain that he did not consider it. Still, the paper marked the beginning of the scientific consideration of friction skin.

Close behind Grew came Bidloo (1685) and Malpighi (1686) with additional descriptions of the morphology of friction skin. Malpighi is perhaps the more important because, while Bidloo published a detailed description of the skin covering the fingers, Malpighi investigated the function of friction skin as a tactile organ and as a means of providing traction for walking and grasping.

Figure 1.3 Fingerprint showing the appearence og dissociated ridges.

In 1788 the first published reference to the potential uniqueness of friction skin appeared in an atlas of medical illustrations by J.C.A. Mayer, who wrote:

Although the arrangement of skin ridges is never duplicated in two persons, nevertheless the similarities are clearer among some individuals. In others the differences are marked, yet in spite of their peculiarities of arrangement all have a certain likeness (Mayer, 1788).

While it is apparent that Mayer’s intent was to point out that prints are similar (perhaps in the same manner that people all have the same number and types of bones) he must be credited with being the first to record that prints are different.

In a thesis about the physiological processes of the skin, Johannes Purkinje (1823) devised the first systematic classification of fingerprint patterns while a university professor in Bohemia. The thesis did not, however, address individuality. The classification he devised utilized nine categories of pattern, each defined quite specifically. That subsequent investigators did not continue or build upon Purkinje’s classification system may be an indication that his role has been overstated in the past.

The first published mention of the possibility of using friction ridged skin as a means of identification appeared as a note in the journal Nature (Faulds, 1880). The author, a doctor serving in a medical mission in Japan, stated much later that his interest was initially aroused when he noticed impressions of fingerprints in Japanese pottery. That his investigation of friction skin was thorough is illustrated by the fact that his Japanese students even went so far as to destroy the skin on their fingers by abrasion, acid, and other methods, so that they could determine if the prints would be changed when their fingers healed.

Faulds’ concept, as published, was that fingerprints would be primarily useful as a technique for investigation of evidence left at scenes of crimes. His article describes two instances in which he used such evidence in Japan:

I have already met with two practical cases in my experience, and was able to use such fingerprints as necessary evidence. In one case someone had left greasy fingerprints on a drinking glass. … In the other case, the sooty fingerprints left by a person climbing over a white wall were of great value as exonerating evidence. (Faulds, 1880)

Shortly after the appearance of Faulds’ first publication, Sir William Herschel wrote to Nature claiming to have discovered the individuality of friction skin long before Faulds. Herschel wrote that he had been using fringerprints for more than 20 years as a colonial official in the Hooghly district in India. He stated further that he had introduced the practice in several government departments in 1877. He also claimed that his experience over those years without finding changes in fingerprints proved the utility of the scheme.

A debate ensued in various journals between Faulds and Herschel regarding who should receive credit for first discovering the individuality of fingerprints and their potential usefulness in personal identification.

It was while researching this controversy, for a lecture to the Royal Institute on the Bertillon system of identification (discussed later in this chapter), that Sir Francis Galton first became interested in fingerprints. Galton had been aware of the subject since about 1880 but did not begin his investigation until 1888. The result of his study was the aforementioned book, Finger Prints (Galton, 1892). In this book, Galton considered virtually every aspect of friction skin including history, morphology, inheritance, individuality, permanence, methods of printing, and potential usefulness. Though most of the data he used are out of date, and the book itself out of print, Finger Prints is a landmark treatise marking the beginning of the modern use of the prints of friction skin as a means of identification.

In Argentina, Dr. Juan Vucetich instituted the use of “icnofalangometrica” in the La Plata police department in 1891. It is interesting that Vucetich^;s use of fingerprints predated the publication of Gallon’s book; he was undoubtably influenced by the writing of Faulds and Herschel. The classification devised by Vucetich is still in use, with local modifications and extensions, in most Spanish-speaking countries.

Besides Faulds, Herschel, and Galton, another British civil servant who figures prominently in the history of the use of fingerprints is Sir Edward Richard Henry. Henry was the Inspector General of Police in Bengal, India and visited Galton in 1893. As a result of that visit he returned to India to institute the use of fingerprints as an aid to identification on a national level. Henry’s classification system, for which he is best known, was devised between 1894 and 1897 with the assistance of two Indian civil servants. In 1897, India officially discarded the use of Bertillonage in favor of the use of fingerprints and the Henry classification system. In 1901, as the Assistant Commissioner in charge of criminal identification at New Scotland Yard, Henry began the use of fingerprints as an adjunct to the use of Bertillonage.

Bertillonage (McLaughery, 1896), named after its originator, French criminologist Alphonse Bertillon, was an identification system much in use in the latter part of the 19th and the very early 20th centuries. In this system individuals were subjected to measurement of various body parts and minute description (the “portrait parle”), (Figure 1.4). The data thus collected were arranged into a formula and filed. The measurements and description of the individual, although performed under rigorous guidelines, were subject to much operator error due to their interpretive nature. As the files for the system grew, first photographs and then fingerprints were added to improve its accuracy.

Perhaps because fingerprints were easier to take, did not depend on the judgment of some person at some other time and place, and were not affected by aging or purposeful changes of appearance, fingerprints gradually replaced Bertillonage as the preferred method of personal identification. In the United States, the use of Bertillonage began a rapid decline in 1903 when two prisoners in the penitentiary at Ft. Leavenworth, Kansas, were found to be indistinguishable on the basis of photographs and Bertillon measurements. In Europe, however, Bertillonage was not abandoned until after the death of Alphonse Bertillon in 1914.

The use of friction skin prints is usually considered to have two distinct functions. The first is record keeping where a complete set of fingerprints of an individual is used to determine the true identity of that individual. The second in criminal matters to implicate an individual as possibly responsible for the criminal activity. In fact, both of these applications are but two sides of the same coin. The only difference is that in record keeping the worker usually has a greater amount of material with which to work and that material is prepared for that specific purpose. In crime investigation, some of th...

Table of contents

• Cover
• Half Title
• Series Page
• Title Page
• Copyright Page
• Dedication
• Table of Contents
• Preface
• Acknowledgments
• 1 Introduction
• 2 Taking Inked Prints
• 3 Classification
• 4 The Evidence Print
• 5 Photography of Prints and Impressions
• 6 The Basis of the Comparison
• 7 Comparing Prints
• 8 Some Comparisons of Evidence Prints
• 9 Reporting and Testifying to Conclusions
• References
• Index