The Science of Fingerprints

The Science of Fingerprints, by

Federal Bureau of Investigation John Edgar Hoover
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Title: The Science of Fingerprints Classification and Uses
Author: Federal Bureau of Investigation John Edgar Hoover
Release Date: August 10, 2006 [EBook #19022]
Language: English
Character set encoding: ISO-8859-1
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THE SCIENCE
OF

FINGERPRINTS
Classification and Uses
UNITED STATES DEPARTMENT OF JUSTICE
FEDERAL BUREAU OF INVESTIGATION
John Edgar Hoover, Director

INTRODUCTION
This booklet concerning the study of fingerprints has been prepared by
the Federal Bureau of Investigation for the use of interested law
enforcement officers and agencies, particularly those which may be
contemplating the inauguration of fingerprint identification files. It is
based on many years' experience in fingerprint identification work out
of which has developed the largest collection of classified fingerprints
in the world. Inasmuch as this publication may serve as a general
reference on classification and other phases of fingerprint identification
work, the systems utilized in the Identification Division of the Federal
Bureau of Investigation are set forth fully. The problem of pattern
interpretation, in particular, is discussed in detail.
Criminal identification by means of fingerprints is one of the most
potent factors in obtaining the apprehension of fugitives who might
otherwise escape arrest and continue their criminal activities
indefinitely. This type of identification also makes possible an accurate
determination of the number of previous arrests and convictions which,
of course, results in the imposition of more equitable sentences by the
judiciary, inasmuch as the individual who repeatedly violates the law
finds it impossible to pose successfully as a first, or minor, offender. In
addition, this system of identification enables the prosecutor to present
his case in the light of the offender's previous record. It also provides
the probation officers, parole board, and the Governor with definite
information upon which to base their judgment in dealing with
criminals in their jurisdictions.

From earliest times fingerprinting, because of its peculiar adaptability
to the field, has been associated in the lay mind with criminal
identification to the detriment of the other useful phases of the science.
However, the Civil File of the Identification Division of the Federal
Bureau of Investigation contains three times as many fingerprints as the
Criminal File. These civil fingerprints are an invaluable aid in
identifying amnesia victims, missing persons and unknown deceased.
In the latter category the victims of major disasters may be quickly and
positively identified if their fingerprints are on file, thus providing a
humanitarian benefit not usually associated with fingerprint records.
The regular contributors who voluntarily submit fingerprints to the
Federal Bureau of Investigation play a most important role in the drama
of identification. Their action expands the size of the fingerprint files,
thereby increasing the value of the files to all law enforcement agencies.
Mutual cooperation and efficiency are resultant by-products.
The use of fingerprints for identification purposes is based upon
distinctive ridge outlines which appear on the bulbs on the inside of the
end joints of the fingers and thumbs. These ridges have definite
contours and appear in several general pattern types, each with general
and specific variations of the pattern, dependent on the shape and
relationship of the ridges. The outlines of the ridges appear most clearly
when inked impressions are taken upon paper, so that the ridges are
black against a white background. This result is achieved by the ink
adhering to the friction ridges. Impressions may be made with blood,
dirt, grease or any other foreign matter present on the ridges, or the
saline substance emitted by the glands through the ducts or pores which
constitute their outlets. The background or medium may be paper, glass,
porcelain, wood, cloth, wax, putty, silverware, or any smooth,
nonporous material.
Of all the methods of identification, fingerprinting alone has proved to
be both infallible and feasible. Its superiority over the older methods,
such as branding, tattooing, distinctive clothing, photography, and body
measurements (Bertillon system), has been demonstrated time after
time. While many cases of mistaken identification have occurred

through the use of these older systems, to date the fingerprints of no
two individuals have been found to be identical.
The background and history of the science of fingerprints constitute an
eloquent drama of human lives, of good and of evil. Nothing, I think,
has played a part more exciting than that enacted by the fascinating
loops, whorls, and arches etched on the fingers of a human being.
[Signature: J. Edgar