From time to time the FBI is requested to conduct surveys and
participate in conferences and in police schools on the problem of
As a result of its observations in the course of these activities it
has been found that many identification bureaus are not fully aware of
the importance which latent finger impressions can have in connection
with the ordinary handling of arrest fingerprint cards.
Many bureaus and departments spend considerable time in developing
latent impressions in a particular case. If no immediate results are
forthcoming, the latent impressions are filed for future reference.
Single fingerprint files have been maintained with success by some
departments. Many others do not attempt to keep a file because of
either limited personnel or lack of funds. In many departments,
however, where such a file is maintained, too often latent impressions
are simply filed with no regard to possible future use. Actually,
these impressions should be treated as evidence directly connecting
the subject with the crime.
Active consideration should be given to the latent impressions until
they are identified or the case has been successfully prosecuted. It
is definitely felt that the following suggested procedure might have
some decided advantages.
It is suggested that in all cases where latent impressions are
developed at the crime scene, or on an object used in connection with
the commission of a crime, the impressions be properly photographed
and lifted. The evidence, where possible and practicable, should be
properly packed, labeled, and stored for future use in court (fig.
Use care in wrapping the evidence to see that the latent impressions
on the objects are not destroyed. If the specimens are later used in
court, the impressions should still be clearly visible. In the same
manner, all evidence not of a bulky nature, such as photographic
negatives, photographs, and lifts of latent impressions, should be
similarly preserved for future court use. It is to be emphasized that
all material in one case should bear a case number. All specimens not
of a bulky nature can be placed in an envelope and filed by this case
number (fig. 431).
The above procedure is the usual one followed by the majority of
identification bureaus in handling latent impressions. In order,
however, to keep the latents in an active state, the photographs of
all the latent impressions found in a particular case should be cut up
and pasted on a 3 by 5 card bearing the case number and title of the
case (fig. 432).
[Illustration: 430. Evidence labeled and latents protected for storing
for future court use.]
[Illustration: 431. Latent material in a case should be filed under a
single case number.]
If numerous latents are developed, several cards should be used, all
having the same number and title. These cards are then filed by case
number in a regular filing cabinet. Before this step is taken, every
effort should be made to secure and compare the fingerprints of
individuals who may legitimately have placed their prints on the
objects which were examined. In addition, as part of the case report
bearing the same case number as the latent impressions, there should
be a notation pointing out that latent impressions were developed in
the case and that they are on file.
[Illustration: 432. For ready current comparisons latents in a case
are placed on a 3 x 5 card bearing case title and number.]
Jones' Drug Co.
Fingerprint comparisons in this unidentified file can be made on the
basis of fingerprints taken from day to day of individuals
fingerprinted for criminal identification purposes. A routine may be
set up whereby the fingerprints of individuals arrested each day will
be compared the following day with the latent fingerprints filed in
the unidentified latent file. It is most important that this procedure
be rigidly followed from day to day. It is to be borne in mind that
the comparisons are made whether the particular person is or is not a
suspect in a certain case. Special attention should be paid to
fingerprints of individuals charged with burglary, breaking and
entering, armed robbery, and other similar crimes.
Should an identification be made of some latent prints, and others in
the same case remain unidentified, the 3 by 5 card should remain in
file until the case is fully closed, inasmuch as more than one person
may be involved in the crime. Of course, if all the latents are
identified, then the 3 by 5 card is removed and placed with the
negatives, lifts, etc.
It may be deemed advisable to remove these latents from the file in
instances where the statute of limitations covering the crime has run.
If the above procedure is rigidly followed, identification in many
instances will result--more than would be effected if the department
maintained only a single fingerprint file in which the latent prints
were merely filed away. Very often such a latent fingerprint file is a
source of information when all logical investigative leads have been
This resume of latent impressions has been prepared by the
Federal Bureau of Investigation in the belief that it may be
of possible interest to law enforcement officers desiring to
avail themselves of latent identification evidence in
connection with their investigative activities. It should be
borne in mind that the comments and expressions set out in
this book are not intended to convey the thought that the
Federal Bureau of Investigation believes the points
emphasized are the only ones of moment, or that other
methods of developing latent impressions are not equally
acceptable. The Federal Bureau of Investigation will be glad
to answer any questions on the foregoing which may occur to
any law enforcement officer who reads this material.