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 classif cation, 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.