Solving the Mystery
When police come upon a crime scene, the first thing that they do is
seal off the area and prevent anyone but experts to enter. They do
this so that their own hair, fingerprints and clothing do not
contaminate the evidence.
Contaminate: to change or alter in a negative way a crime scene
can be contaminate by other people’s fingerprints.
Fingerprint Patterns
 Fingerprints can be decided into three main patterns:
loops, whorls, and arches.
 A clear fingerprint is excellent evidence.
 No two fingerprints in the world are alike.
 A Fingerprint will remain unchanged during an
individuals lifetime (unless scars appear)
 Twins?
Types of Fingerprints
Deltas
 Not a type of fingerprint, but it helps us to classify the
finger prints. A delta is a triangular pattern on the
finger print as shown in the picture below.
Arches
Arches are found in about 5% of fingerprint patterns
encountered. The arch pattern of finger print is like a wave or a
hill. The ridges enter on one side of the print, rise in the middle
and exit on the opposite side of the print. The arch print has no
delta.
Whorls
Whorls are seen in about 25-35 % of fingerprint patterns.
In a whorl, some of the ridges make a turn through at
least one circuit. Any fingerprint pattern which contains 2
or more deltas (triangle) will be a whorl pattern.
Loops
 Loops are the most common fingerprint and is in 6065% of the population. Must have one or more ridges
entering from one side of the print, curving and
exiting from the same side. It has one delta.
Composite
 The composite pattern is a combination of patterns
such as a whorl and arch, a loop and an arch, or a
whorl and a loop
Other Than The Type
 When the police identify fingerprints, the first thing
they do is look at the pattern of the print i.e., loop,
whorl, arch or composite.
 Once they have a matching pattern type, they look for
unique features of a print to help them match a suspect
to the fingerprints found at the scene of a crime
Ridge Characteristics
 In order for the print to be considered "a match" they
must have a number of ridge characteristics in
common
Bifurcation (fork)
 One ridge splits to form
two ridges and then
rejoin to one ridge again,
forming a shape like a
lake.
Ridge Endings
 A ridge ends.
Islands
 A very short ridge in the
print pattern is not
connected to any other
ridge, much like an
island floating by itself.
Lakes
 A circle shape in the
middle of a ridge
Deltas
 Many fingerprints have
unique delta’s that would
also will qualify as a
ridge characteristic
All together
Others