Fingerprint Analysis Laboratory Workbook
4
PLAIN ARCH
PLAIN WHORL
TENTED ARCH
CENTRAL POCKET
LOOP WHORL
RIGHT-SLANTED
LOOP
DOUBLE-LOOP
WHORL
LEFT-SLANTED
LOOP
ACCIDENTAL
WHORL
Figure 1.1
The eight fingerprint sub-pattern types: plain arch, tented arch, right-slanted loop, left-slanted loop, plain whorl, central pocket
loop whorl, double-loop whorl, and accidental whorl.
Bifurcation
Ending Ridge
Dot
Figure 1.2
A bifurcation, dot, and ending ridge in a magnified portion of a fingerprint.
fingerprints in the population are loop patterns, while whorls are much less common, and arches are rare.
Finding a latent print with an arch pattern at a crime scene is valuable for elimination purposes, because
they are so rare in the population. Conversely, finding a latent print with a loop pattern at a crime scene is
not as discriminating, because loops are very common in the population.
While pattern types can be used to narrow down the population of fingerprints or eliminate a subject as
the possible contributor of a latent print, they do not have individualizing power. Minutiae are individualizing
characteristics. They can be used to narrow down the potential source of a latent print. There are three types
of fingerprint minutiae: bifurcations, ending ridges, and dots (Figure 1.2). While all individuals have ending
ridges and bifurcations present along friction ridges, an analysis of the relative locations of those minutiae
in the impression makes it possible to identify the potential source of a latent print. An analysis of both the
class characteristics (pattern types, ridge flow, level 3 detail) and individual characteristics (minutiae types
and relative locations) contribute to fingerprint identification. In the following laboratory exercises, you will
explore the class and individual characteristics of various types of forensic evidence as well as the three types
of fingerprint minutiae.