picture even
though only the upper portion of the individual photographed is taken.
Of course, if the scale is used, the person photographed should be
standing even though only the upper portion of the body appears in the
photograph. The necessary lights should be provided for obtaining
photographs. A standard set of scales should be obtained in order that
the correct weight can be ascertained.

[Illustration: 419]

The negatives and photographs can be filed by fingerprint number in a
separate file. In those cases where the individual has more than one
arrest all the photographs can be placed in the jacket-folder number
file. The negatives, in these instances, can remain in the photograph
file.

_Latent fingerprints_

To adequately develop the latent prints at crime scenes, it is
necessary that the proper equipment be provided. This equipment
includes latent fingerprint powders, brushes, lifting tape,
fingerprint camera, searchlight, and scissors. All of this equipment
can be obtained from commercial fingerprint supply companies. Figure
419 shows some of the equipment used by the FBI. The techniques of
developing latent fingerprints and their uses are more fully explained
in the following chapters.

It is believed that by following the basic ideas outlined, the
officials of law enforcement agencies can be assured of best results
in establishing and maintaining a small identification bureau. For
further information, the Federal Bureau of Investigation will furnish
to duly constituted law enforcement officials any additional data
which may be of material assistance in the maintenance of such a
bureau.

CHAPTER XII

_Latent Impressions_

Each ridge of the fingers, palms, and soles bears a row of sweat pores
which in the average person constantly exude perspiration. Also, the
ridges of the fingers and palms are in intermittent contact with other
parts of the body, such as the hair and face, and with various
objects, which may leave a film of grease or moisture on the ridges.
In touching an object, the film of moisture and/or grease may be
transferred to the object, thus leaving an outline of the ridges of
the fingers or palm thereon. This print is called a latent impression,
the word "latent" meaning hidden, that is, the print many times is not
readily visible.

Latent impressions, regardless of the area of the ridges present, are
of the greatest importance to the criminal investigator as
identifica