_Searching and Referencing_
_Searching_
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 finger and this number is used as the
final. It will also be noted that there is a loop of 24 ridge counts
in the right thumb and this number is used as the key inasmuch as it
is the first loop. In this example, the print is searched in the group
classification which has finals ranging from 15 through 19. Within
this group of finals the prints which have keys ranging from 22
through 26 are examined.
_Referencing_
Too much stress cannot be placed upon the necessity of referencing
questionable patterns, whether it be in the interpretation of the type
of pattern, the ridge count, or the tracing.
The factors which make it necessary are: variation in individual
judgment and eyesight, the amount of ink used, the amount of pressure
used in taking the prints, the difference in width of the rolled
impressions, skin diseases, worn ridges due to age or occupations,
temporary and permanent scars, bandaged fingers, crippled hands, and
amputation.
_For the highest degree of accuracy, all rolled impressions should be
checked by the plain impressions_, which generally are not distorted
by pressure. This also helps prevent error caused by the reversal or
mixing of the rolled impressions out of their proper order. For the
same reason, as much of the counting and tracing should be done in the
plain impressions as it is possible to do.
If there is any doubt as to which of two or more classifications
should be assigned to a given pattern, it is given the preferred
classification and reference searches are conducted in all other
possible classifications. For example, if on a print with the
preferred classification
1 A
----
1 Aa
it is questionable whether the left middle finger should be a plain
arch, a tented arch, or a radial loop, the print is searched in the
1 A
----
1 Aa
group, and reference searches are conducted in the
1 A
----
1 At
and
1 A
----
1 Ar
groups. For further illustration, a print is given a preferred primary
classification of
1,
-
1
although the ridge detail on the right thumb is so formed as to
resemble a whorl. The search is completed first in the preferred
1
-
1
primary classification and a reference search is then conducted in the
1
--
17
primary.
All ridge counts that are "line counts," i.e., when one more or one
less count would change the designation of the loop from I to O or
from S to M, etc., must be searched in both groups. For example, in a
print classified
16 M 1 U III 10,
---------------
M 1 U III
if the ridge count of the right middle finger is 10 and the count in
the right thumb is 16 (as indicated by the key), the print would be
searched first as classified, then reference searches would be
conducted in the following groups:
M 1 U IOI, L 1 U III, L 1 U IOI
--------- --------- and ---------
M 1 U III M 1 U III M 1 U III
When there is doubt concerning the tracing of a whorl, it should be
treated in the same fashion. For example, if in the classification
O 5 U
------
I 17 U
doubt existed as to whether the tracing of the right thumb might not
be a meeting tracing, the print would be searched as classified, and a
reference search would be conducted in
M 5 U.
------
I 17 U
If there is no doubt concerning the ridge count used for the final, it
is enough to search out of the group only those prints containing a
final within 2 ridge counts on each side of the final on the print
being searched. When, however, there is doubt concerning the ridge
count of the final, the print should be searched 2 ridge counts on
each side of the two extremes of possibility. For example, if it were
possible for a final to be 6, 7, 8, or 9 ridge counts, the print
should be searched through that part of the group bearing finals of
from 4 through 11.
The above explanation pertaining to the final also applies to the key.
All prints bearing amputations should be referenced to the necessary
files containing prints other than amputations for reference searches.
In instances where only one finger is amputated, reference searches
are conducted in all possible classifications, including all possible
ridge counts or tracings. For example, a print containing the
classification:
AMP
4 S 1 U III 6
-------------
S 1 U III
with the right index finger amputated, the left index finger being an
ulnar loop, would be searched first in the amputation group for the
classification, then reference searches would be conducted in the
following groups in the nonamputation files:
S 1 U III S 1 T II S 17 W III
--------- --------- ----------
S 1 U III S 1 U III S 1 U III
S 1 U OII S 1 R III S 17 W MII
--------- --------- ----------
S 1 U III S 1 U III S 1 U III
S 1 A II S 1 R OII S 17 W OII
--------- --------- ----------
S 1 U III S 1 U III S 1 U III
All prints bearing unprinted or badly crippled fingers are filed in
the nonamputation files, and reference searches are conducted in the
amputation group.
For the purpose of determining if it is feasible to conduct reference
searches in all possible classifications, the method of referencing
amputations is applied to completely scarred patterns (Chapter titled
"Scarred Patterns--Amputations--Missing at Birth"). For example, a
print bearing the preferred classification:
13 O 17 W OOO 14
----------------
L 17 U OOI
with the left middle finger completely scarred, the right middle
finger being an ulnar loop with a ridge count of 13, would be searched
first in the group for that classification, then reference searches
would be conducted in the following groups:
O 17 W OOO O 17 W O 19 W OOO
---------- ------- ----------
L 17 U OII L 17 Ur L 17 U OOI
O 17 W O 19 W OOO
------- ----------
L 17 Ua L 17 U OII
O 17 W O 19 W OOO
------- ----------
L 17 Ut L 17 U OMI
The referencing of partial scars is a problem in which many factors
are present. A full explanation of the scars, their preferred
classifications and their references is made in the chapter,
"Classification of Scarred Patterns--Amputations--Missing at Birth."
When the age extension is utilized and a "Reference" group and a
"Presumptive Dead" file are maintained, it is suggested that a general
allowance of 5 years be considered to allow for a discrepancy in
prints bearing the ages of 50 years or older.
In the files of the Federal Bureau of Investigation the various age
groups are as follows:
1-54 "Regular" file.
55-74 "Reference" file.
75 and over "Presumptive Dead" file.
Reference searches for the preceding groups are conducted in the
following manner:
50-54 Referenced to "Reference" file.
70-74 Referenced to "Presumptive Dead" file and "Regular" file.
75-79 Referenced to "Reference" file and "Regular" file.
80 and older Referenced to "Regular" file only.
If no age is given, it should be searched first in the regular file
and reference searches should be conducted in the "Reference" group
and the "Presumptive Dead" file.
When separate male and female files are maintained, there may be doubt
as to the sex of a subject due to a discrepancy between the sex
indicated and the name and the description and picture. In such case
try to determine the sex from the description and the size of the
prints, then reference the print to the other file. A Photostat copy
can be made and placed in the other file until the true sex can be
determined.