Latent Print Development - National Criminal Justice Reference ...

C H A P T E R 7 Latent Print Development
rub off on contact. Once evidence is secured, the pack-
age should be sealed with evidence tape so that there are
no entry points. The tape should be signed by the person
securing the evidence, and the appropriate identifying
information should be placed on the package as specified
by the agency responsible for collection.
The remainder of this chapter is intended to describe,
in some detail, the nature of latent print residue and the
most commonly used fingerprint development techniques.
Experimental and novel techniques have not been included,
nor have processes considered by the authors to be redun-
dant, impractical, or overly hazardous. However, the omis-
sion of reference to a particular technique does not indicate
its unsuitability as a fingerprint development technique.
Several formulations for various chemical solutions have
been collected in Section 7.14.
7.2 The Composition of Latent
Print Residue
7.2.1 Introduction
The composition of sweat that is deposited when fric-
tion ridge skin makes contact with a surface is a complex
mixture (Ramotowski, 2001, pp 63–104; Bramble and
Brennan, 2000, pp 862–869). Recent studies have identi-
fied hundreds of compounds present in human sweat
(Bernier et al., 1999, pp 1–7; Bernier et al., 2000, pp 746–
756). A considerable number of studies into the nature of
sweat have been performed by both the dermatology and
forensic science communities. In particular, a number of
studies have investigated how the chemical composition
of these residues changes with time, which is a critical
problem for the fingerprint examiner. Although knowledge
of the composition of sweat produced in the various glands
throughout the body is of interest and provides a baseline
for comparison purposes, this information does not accu-
rately represent what is actually going on in the deposited
print at a crime scene. Studies have shown that significant
changes begin to occur in the latent print almost immedi-
ately after deposition. If the latent print is to be success-
fully visualized, a thorough understanding of these changes
is needed.
This section will begin with a very brief overview of skin
anatomy, which will be necessary to gain a better under-
standing of how the chemical compounds in a latent print
7–6
are secreted onto the surface of friction ridge skin. Next,
there will be a detailed look at the chemical composition
of the secretions from each of the glands responsible for
contributing to latent print residue. Another section will
cover how the composition of some of these secretions
changes as the donor ages. Finally, recent studies that
have investigated how latent print residue changes with
time will be summarized.
7.2.2 Anatomy of Skin
This topic is covered in more detail elsewhere in this source-
book, so the treatment here will be very brief. Readers are
directed to Ramotowski (2001, pp 63–104) for more detail.
Skin is the largest organ in the human body (Odland, 1991).
The total area of skin on the body exceeds 2 m 2 ; yet, on
most parts of the body, the thickness is no more than 2
mm. Skin serves several functions, including regulation
of body temperature, moisture retention, protection from
invasive organisms (e.g., viruses, bacteria), and sensa-
tion. It is composed of two primary and distinct layers, the
epidermis and dermis.
The epidermis is composed of several distinct layers
(Ramotowski, 2001, pp 63–104; Odland, 1991). The layer
situated just above the dermis is the stratum germinativum
(basal cell layer), and the top layer is the stratum corneum
(cornified layer). In this stratum, eleiden is converted to
keratin, which is continually sloughed off the surface of the
epidermis, resulting in a constant need to replenish the
keratin that is lost. A cell beginning in the stratum germina-
tivum typically travels through to the stratum corneum in
about 28 days.
The dermis is composed of a variety of different connective
tissues, including collagen, elastin fibers, and an interfi-
brillar gel composed of glycosamin–proteoglycans, salts,
and water (Odland, 1991). This layer also contains the two
major sudoriferous and sebaceous glands.
7.2.3 The Production of Sweat
Three primary glands contribute to the production of
sweat. These are the sudoriferous glands (eccrine and apo-
crine) and the sebaceous glands. Each gland contributes a
unique mixture of chemical compounds. These compounds
either exude from pores onto the friction ridges or are
transferred to the friction ridges through touching an area
(e.g., the forehead, underarm, etc.).