Fingerprints and human identification 89absorbed back into the finger at about the tenth or eleventh week of gestation,
when friction ridges begin to form. Primary ridges develop first, followed
by secondary ridge development or the occurrence of furrows between the
papillary ridges. Although most of this activity has a genetic component, a
nearly infinite number of environmental factors result in the random devel-
opment (differential growth) of friction ridges and their corresponding level 2
and 3 detail. The end result of these genetic and environ mental variances
during friction ridge formation is complete biological uniqueness, down to
the structure of a single ridge.
Persistency refers to the fact that friction ridges are permanent and
remain constant throughout a person’s lifetime, until decomposition after
death, unless otherwise affected by accidental injury or intentional mutila-
tion. The basis for this statement rests in human anatomy and the histology
of the skin. As the body sloughs off dead skin cells, they are replaced by new
skin cells generated from the bottom or basal layer of the epidermis.^12 The
cells joined together through cell junctions are replaced the same way for an
entire lifetime unless scarring occurs. Thus, the basal layer acts as an immu-
table root system that is the foundation for the permanency of friction ridges
and their corresponding level 1, 2, and 3 detail.
6.5 The Postmortem Fingerprint Recovery ProcessIt has been said by some in the forensic community that there is little dif-
ference between obtaining fingerprints from the living and the dead. Those
in the fingerprint profession involved with victim identification understand
that recovering quality friction ridge impressions from human remains can
be one of the most challenging tasks that an examiner can perform. This
task differs markedly from printing the living on many levels and requires
both mental composure and physical dexterity on the part of the forensic
examiner for successful completion.
While fingerprints are obtained from both the living and the dead for iden-
tification purposes, the reasoning and mind-set behind the action are different.
For example, most examiners can recall the first time they examined human
remains, whereas very few can recall with any certainty the first time they
finger printed the living. The psychological aspects of working with the dead,
especially in mass fatality situations, are being addressed by many organiza-
tions involved with forensic identification operations throughout the world.
Some techniques used to assist examiners in overcoming stresses associated
with human identification include mandatory leave, favored by European orga-
nizations, and debriefing sessions, favored by U.S. agencies, to include the FBI.
The technical aspects of fingerprinting the living and dead might appear
similar on the surface, but in most cases they are considerably different. The