The Science of Fingerprints by United States. Federal Bureau of Investigation (books to read in a lifetime txt) 📕
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If, however, in the case of an injured finger, observation is made of the ridges of the finger itself and indicated on the print, this classification should be, insofar as it is possible, utilized. For example, a missing impression labeled "ulnar loop of about 8 counts" by the individual taking the prints, should be searched in the subsecondary as both I and O but should not be referenced as a pattern other than a loop. If the finger is used as the final, or key, it should be searched enough counts on each side of 8 to allow for possible error in the counting by the contributor using his naked eye.
CHAPTER VI Filing Sequence
The sequence must be arranged properly at all times to make possible the most accurate work. Prints are sequenced and filed in this order, according to:
I. Primary:
1 to 32. 1 32In the primary classification the denominator remains constant until all numerator figures have been exhausted from 1 to 32. All prints with the primary 1 over 1 are filed together. These are followed by 2 over 1, 3 over 1, 4 over 1, etc., until 32 over 1 is reached. The next primary is 1 over 2, then 2 over 2, etc., until 32 over 2 is reached. Eventually, through the use of each denominator figure and the elimination of each numerator over each denominator, the 32 over 32 primary will be reached.
Even in the smaller collections of fingerprints, it will be found that the groups which are arranged under the individual primaries filed in sequence, from 1 over 1 to 32 over 32, will be too voluminous for expeditious searching.
II. Secondary:
A. Secondary small-letter group:
A r to W3r. A r W3rMost intricate of all the individual sequences is the small-letter sequence. It is less difficult if the following method is used:
1. Sequence according to the patterns in the index fingers, grouped
A to W. A WWhen small letters are present, there are 25 possible combinations which can appear in the index fingers. They are as follows:
- - - - -
A A A A A
A T R U W
- - - - -
T T T T T
A T R U W
- - - - -
R R R R R
A T U R W
- - - - -
U U U U U
A T U R W
- - - - -
W W W W W
2. Within each group sequence:
a. The denominator, by—
(1) Count of the small letters (lesser preceding the greater).
(2) Position of the small letters (those to the left preceding those to the right).
(3) Type of small letter (sequence a, t, r).
b. The numerator, by—
(1) Count.
(2) Position.
(3) Type.
Thus
A precedes T A AA precedes A rAt A3t
A precedes A aA Aa
A precedes A At Ar
aA precedes aAa aAr aAr
rA precedes Ar aA2a aA2a
aAtat precedes aAtar tA3r tA3r
The following table represents the full sequence of the denominator of the group having A over A in the index fingers. The full sequence as listed may be used as the numerator for each denominator as set out below. Following the group with A over A in the index fingers is the group with T over A in the index fingers, the sequence being the same otherwise. Then R over A, U over A, A over T to rW3r over rW3r.
A tAra aA2at tA2tr aA tArt aA2ar tAtra tA tA2r aAata tAtrt rA rA2a aAa2t tAt2r Aa rAat aAatr tAr2a At rAar aAara tArat Ar rAta aAart tArar aAa rA2t aAa2r tArta aAt rAtr aAt2a tAr2t aAr rAra aAtat tArtr tAa rArt aAtar tA2ra tAt rA2r aA2ta tA2rt tAr A3a aA3t tA3r rAa A2at aA2tr rA3a rAt A2ar aAtra rA2at rAr Aata aAtrt rA2ar A2a Aa2t aAt2r rAata Aat Aatr aAr2a rAa2t Aar Aara aArat rAatr Ata Aart aArar rAara A2t Aa2r aArta rAart Atr At2a aAr2t rAa2r Ara Atat aArtr rAt2a Art Atar aA2ra rAtat A2r A2ta aA2rt rAtar aA2a A3t aA3r rA2ta aAat A2tr tA3a rA3t aAar Atra tA2at rA2tr aAta Atrt tA2ar rAtra aA2t At2r tAata rAtrt aAtr Ar2a tAa2t rAt2r aAra Arat tAatr rAr2a aArt Arar tAara rArat aA2r Arta tAart rArar tA2a Ar2t tAa2r rArta tAat Artr tAt2a rAr2t tAar A2ra tAtat rArtr tAta A2rt tAtar rA2ra tA2t A3r tA2ta rA2rt tAtr aA3a tA3t rA3r
B. Secondary loop and whorl group:
R to W. R WWhen no small letters are present, there are 9 possible combinations which can appear in the index fingers. They are as follows:
- - -
R R R
R U W
- - -
U U U
R U W
- - -
W W W
At this point it is well to note that it may be preferable in some instances where small files are concerned to use only a portion of the classification formula in the filing sequence. In such cases, only those parts of the filing sequence which are necessary should be used along with the final and key.
III. Subsecondary:
III to OOO. III OOOThe sequence of the subsecondary is as follows:
--- --- --- --- --- --- ---
III III III III III III III
IOM IOO MII MIM MIO MMI MMM
--- --- --- --- --- --- ---
III III III III III III III
MMO MOI MOM MOO OII OIM OIO
--- --- --- --- --- --- ---
III III III III III III III
OMI OMM OMO OOI OOM OOO OOO,
--- --- --- --- --- --- etc., to ---
III III III III III III OOO
each numerator in turn becoming the denominator for the complete sequence of numerators as listed above.
IV. Major:
The following sequence is used when loops appear in both thumbs:
- - - - - - - - -
S S S M M M L L L
When whorls appear in both thumbs the sequence is:
- - - - - - - - -
I I I M M M O O O
When a whorl appears in the right thumb and a loop in the left, the sequence is:
- - - - - - - - -
S S S M M M L L L
When a loop appears in the right thumb and a whorl in the left, the sequence is:
- - - - - - - - -
I I I M M M O O O
V. Second Subsecondary:
SSS to LLL. SSS LLLThe sequence for filing the second subsecondary is as follows:
--- --- --- --- --- ---
SSS SSS SSS SSS SSS SSS
SLS SLM SLL MSS MSM MSL
--- --- --- --- --- ---
SSS SSS SSS SSS SSS SSS
MMS MMM MML MLS MLM MLL
--- --- --- --- --- ---
SSS SSS SSS SSS SSS SSS
LSS LSM LSL LMS LMM LML
--- --- --- --- --- ---
SSS SSS SSS SSS SSS SSS
LLS LLM LLL, LLL,
--- --- --- etc., to ---
SSS SSS SSS LLL
each group of the numerator becoming in turn the denominator for the complete sequence of numerators as listed above.
VI. W C D X Extensions:
W to xX3x. W xX3xThe sequence is as follows: Prints with c, d, or x in any finger other than the index fingers constitute the small-letter group. A sample of the sequence follows:
cW cWd xWx Wxc
dW cWx W2c Wxd
xW dWc Wcd W2x
Wc dWd Wcx cW2c
Wd dW Wdc cWcd
Wx xWc W2d cWcx
As may be readily seen, the sequence proceeds in the same fashion as the a, t, r, small-letter sequence.
VII. Special Loop Extension used by the Federal Bureau of Investigation:
111 to 777. 111 777The following is a partial sequence for filing this extension:
--- --- --- --- --- --- ---
111 111 111 111 111 111 111
121 122 123 124 125 126 127
--- --- --- --- --- --- ---
111 111 111 111 111 111 111
131 132 133 134 135 136 137
--- --- --- --- --- --- ---
111 111 111 111 111 111 111
141 142 143 144 145 146 147
--- --- --- --- --- --- ---
111 111 111 111 111 111 111
151 152 153 154 155 156 157
--- --- --- --- --- --- ---
111 111 111 111 111 111 111
161 162 163 164 165 166 167
--- --- --- --- --- --- ---
111 111 111 111 111 111 111
171 172 173 174 175 176 177 777.
--- --- --- --- --- --- --- etc., to ---
111 111 111 111 111 111 111 777
No matter how many of these divisions may be used, the order should remain the same; and no matter how many of these divisions are used, each individual group should be sequenced by:
VIII. Final:
Filed in numerical sequence from 1 out. For example, assume that there are 15 prints in a group having a final of 14. All of these should be filed together and followed by those prints in the same group having a final of 15, etc.
IX. Key:
All prints appearing in a designated final group are arranged by key in numerical sequence from 1 out. For example, assume that there are 5 prints in a group having a key of 14. All of these should be filed together and followed by those prints in the same group having a key of 15, etc.
CHAPTER VII Searching and ReferencingSearching
When searching a print through the fingerprint files in order to establish an identification, it should be remembered that the fingerprint cards are filed in such a way that all those prints having the same classification are together. Thus, the print being searched is compared only with the groups having a comparable classification, rather than with the whole file.
After locating the proper group classification, the searcher should fix in his mind the one or two most outstanding characteristics of the patterns of the current print and look for them among the prints in file. If a print is found which has a characteristic resembling one upon the current print, the two prints should be examined closely to determine if identical. To avoid making an erroneous identification, the searcher should be exceedingly careful to ascertain that the prints being compared are identical in all respects before identifying one against the other.
To establish identity, it is necessary to locate several points of identity among the characteristics of the prints. The number of identical characteristics is left to the discretion of the individual but he should be absolutely certain that the prints are identical before treating them as such. Characteristics need not appear within the pattern area, since any ridge formation is acceptable. Quite often excellent ridge detail appears in the second joint of the finger. The characteristics used to establish an identification are shown in figure 102.
The final and the key may be considered control figures for searching prints. They limit the number of prints it is necessary to search in a group to those prints having finals and keys closely related to the final and key of the print being searched.
Due to the possibility of visual misinterpretation, distortion by pressure, or poor condition of the ridge detail of the prints in file, it is advisable to allow a margin for such discrepancies. Except in cases where the ridge count of the final and/or key is questionable on the print being searched, the following procedure is used:
Of the prints within any group classification, only those prints are examined which have a final within 2 ridge counts on each side of the final of the print being searched. For example, if the print to be searched has a final of 17, all prints bearing a final 15 through 19 will be compared with it.
Within the final of any group classification, only those prints are examined which have a key within 2 ridge counts on each side of the key of the print being searched. For example, if the print to be searched has a key of 20, all prints bearing a key of 18 through 22 will be compared with it.
In figure 352, it will be noted that there are 17 ridge counts appearing in the right little
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