The Science of Fingerprints - United States. Federal Bureau of Investigation (great novels to read .txt) 📗
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In very rare cases persons without hands are arrested. A file on footprints is maintained in the Identification Division on such individuals.
In view of the fact that many individuals in the underworld are known only by their nicknames, the Identification Division has for years maintained a card-index file containing in alphabetical order the nicknames appearing on fingerprint cards. When requesting a search of the nickname file, it is desired that all possible descriptive data be furnished.
The Latent Fingerprint Section handles latent print work. Articles of evidence submitted by law enforcement agencies are processed for the development of latent impressions in the Latent Fingerprint Section. In addition, photographs, negatives, and lifts of latents are scrutinized for prints of value for identification purposes. Photographs of the prints of value are always prepared for the FBI's files and are available for comparisons for an indefinite period. Should the law enforcement agency desire additional comparisons it needs only advise the FBI Identification Division, attention Latent Fingerprint Section, and either name or submit the prints of the new suspect. It is not necessary to resubmit the evidence. When necessary, a fingerprint expert will testify in local court as to his findings. Should a department have any special problems involving the development or preservation of fingerprints at a crime scene, the experts are available for suggestions. In connection with the Latent Fingerprint Section there is maintained a general appearance file of many confidence game operators. Searches in this file will be made upon request. In furnishing data on a suspect, the agency should make sure that complete descriptive data is sent in. Photographs and other material on individuals who may be identical with those being sought will be furnished to the interested departments.
During the years many persons have voluntarily submitted their fingerprints to the Identification Division for possible use in the case of an emergency. These cards are not filed with the criminal fingerprints but are maintained separately. Such prints should be taken on the standard fingerprint form entitled "Personal Identification" (Form FD-353). No answer is given to Personal Identification fingerprint cards.
The fingerprint records of the FBI Identification Division are used liberally not only by police agencies to obtain previous fingerprint histories and to ascertain whether persons arrested are wanted elsewhere, but by prosecutors to whom the information from the Bureau's files may prove to be valuable in connection with the prosecution of a case. These records are likewise of frequent value to the judge for his consideration in connection with the imposition of sentence. Obviously, the ends of justice may be served most equitably when the past fingerprint record of the person on trial can be made known to the court, or information may be furnished to the effect that the defendant is of hitherto unblemished reputation.
It should be emphasized that FBI identification records are for the OFFICIAL use of law enforcement and governmental agencies and misuse of such records by disseminating them to unauthorized persons may result in cancellation of FBI identification services.
CHAPTER II Types of Patterns and Their InterpretationTypes of patterns
Fingerprints may be resolved into three large general groups of patterns, each group bearing the same general characteristics or family resemblance. The patterns may be further divided into sub-groups by means of the smaller differences existing between the patterns in the same general group. These divisions are as follows:
I. ARCH II. LOOP III. WHORL a. Plain arch. a. Radial loop. a. Plain whorl. b. Tented arch. b. Ulnar loop. b. Central pocket loop. c. Double loop. d. Accidental whorl.
Illustrations 1 to 10 are examples of the various types of fingerprint patterns.
Figs. 1-2
Figs. 3-8
Figs. 9-10
[Figs. 1-10]
Interpretation
Before pattern definition can be understood, it is necessary to understand the meaning of a few technical terms used in fingerprint work.
The pattern area is the only part of the finger impression with which we are concerned in regard to interpretation and classification. It is present in all patterns, of course, but in many arches and tented arches it is impossible to define. This is not important, however, as the only patterns in which we need to define the pattern area for classification purposes are loops and whorls. In these two pattern types the pattern area may be defined as follows:
The pattern area is that part of a loop or whorl in which appear the cores, deltas, and ridges with which we are concerned in classifying.
The pattern areas of loops and whorls are enclosed by type lines.
Type lines may be defined as the two innermost ridges which start parallel, diverge, and surround or tend to surround the pattern area.
Figure 11 is a typical loop. Lines A and B, which have been emphasized in this sketch, are the type lines, starting parallel, diverging at the line C and surrounding the pattern area, which is emphasized in figure 12 by eliminating all the ridges within the pattern area.
Figs. 11-12
[Figs. 11-12]
Figures 72 through 101 should be studied for the location of type lines.
Type lines are not always two continuous ridges. In fact, they are more often found to be broken. When there is a definite break in a type line, the ridge immediately outside of it is considered as its continuation, as shown by the emphasized ridges in figure 13.
Fig. 13
[Fig. 13]
Sometimes type lines may be very short. Care must be exercised in their location. Notice the right type line in figure 14.
Fig. 14
[Fig. 14]
When locating type lines it is necessary to keep in mind the distinction between a divergence and a bifurcation (fig. 15).
Fig. 15
[Fig. 15]
A bifurcation is the forking or dividing of one line into two or more branches.
A divergence is the spreading apart of two lines which have been running parallel or nearly parallel.
According to the narrow meaning of the words in fingerprint parlance, a single ridge may bifurcate, but it may not be said to diverge. Therefore, with one exception, the two forks of a bifurcation may never constitute type lines. The exception is when the forks run parallel after bifurcating and then diverge. In such a case the two forks become the two innermost ridges required by the definition. In illustration 16, the ridges marked "A—A" are type lines even though they proceed from a bifurcation. In figure 17, however, the ridges A—A are not the type lines because the forks of the bifurcation do not run parallel with each other. Instead, the ridges marked "T" are the type lines.
Fig. 16
[Fig. 16]
Fig. 17
[Fig. 17]
Angles are never formed by a single ridge but by the abutting of one ridge against another. Therefore, an angular formation cannot be used as a type line. In figure 18, ridges A and B join at an angle. Ridge B does not run parallel with ridge D; ridge A does not diverge. Ridges C and D, therefore, are the type lines.
Fig. 18
[Fig. 18]
Focal points—Within the pattern areas of loops and whorls are enclosed the focal points which are used to classify them. These points are called delta and core.
The delta is that point on a ridge at or in front of and nearest the center of the divergence of the type lines.
It may be:
● A bifurcation
● An abrupt ending ridge
● A dot
● A short ridge
● A meeting of two ridges
● A point on the first recurving ridge located nearest to the center and in front of the divergence of the type lines.
The concept of the delta may perhaps be clarified by further exposition. Webster furnishes the following definition: "(1) Delta is the name of the fourth letter of the Greek alphabet (equivalent to the English D) from the Phoenician name for the corresponding letter. The Greeks called the alluvial deposit at the mouth of the Nile, from its shape, the Delta of the Nile. (2) A tract of land shaped like the letter "delta," especially when the land is alluvial, and enclosed within two or more mouths of a river, as the Delta of the Ganges, of the Nile, of the Mississippi" (fig. 19).
Fig. 19
[Fig. 19]
When the use of the word "delta" in physical geography is fully grasped, its fitness as applied in fingerprint work will become evident. Rivers wear away their banks and carry them along in their waters in the form of a fine sediment. As the rivers unite with seas or lakes, the onward sweep of the water is lessened, and the sediment, becoming comparatively still, sinks to the bottom where there is formed a shoal which gradually grows, as more and more is precipitated, until at length a portion of the shoal becomes higher than the ordinary level of the stream. There is a similarity between the use of the word "delta" in physical geography and in fingerprints. The island formed in front of the diverging sides of the banks where the stream empties at its mouth corresponds to the delta in fingerprints, which is the first obstruction of any nature at the point of divergence of the type lines in front of or nearest the center of the divergence.
In figure 20, the dot marked "delta" is considered as the delta because it is the first ridge or part of a ridge nearest the point of divergence of the two type lines. If the dot were not present, point B on ridge C, as shown in the figure, would be considered as the delta. This would be equally true whether the ridges were connected with one of the type lines, both type lines, or disconnected altogether. In figure 20, with the dot as the delta, the first ridge count is ridge C. If the dot were not present, point B on ridge C would be considered as the delta and the first count would be ridge D. The lines X—X and Y—Y are the type lines, not X—A and Y—Z.
Fig. 20
[Fig. 20]
In figures 21 to 24, the heavy lines A—A and B—B are type lines with the delta at point D.
Figs. 21-24
[Figs. 21-24]
Figure 25 shows ridge A bifurcating from the lower type line inside the pattern area. Bifurcations are also present within this pattern at points B and C. The bifurcation at the point marked "delta" is the only one which fulfills all conditions necessary for its location. It should be understood that the diverging type lines must be present in all delta formations and that wherever one of the formations mentioned in the definition of a delta may be, it must be located midway between two diverging type lines at or just in front of where they diverge in order to satisfy the definition and qualify as a delta.
Fig. 25
[Fig. 25]
When there is a choice between two or more possible deltas, the following rules govern:
● The delta may not be located at a bifurcation which does not open toward the core.
In figure 26, the bifurcation at E is closer to the core than the bifurcation at D. However, E is not immediately in front of the divergence of the type lines and it
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