Fingerprints - Dermatoglyphics
What Are Fingerprints?
 Raised ridges of skin
on the hairless surfaces
of hands and feet
(Dermal Ridges)
 Primates and other
animals have them
 Provide traction and
every ridge contains a
gland
When Do Fingerprints Form?
 Begin to develop in the 10th week of
gestation and are complete by the 24th
week
 Chance, environment, and heredity all play
a role in the development of an individuals
fingerprints
Three Principals of Fingerprints
1.  A fingerprint is an individual characteristic
a.  No two fingers have the same fingerprint
b.  Identical twins are similar but not identical
2.  Fingerprints remain unchanged during a
lifetime
3.  Fingerprints have general ridge patterns
that permit them to be classified
Three Types of Fingerprints
Plastic Impressions.
  Made in soft material like butter, soap, etc.
Visible Prints.
  Prints made when fingers have been covered
in blood, dirt, oil, paint, etc.
Latent Prints.
  Prints not visible to the human eye, hidden,
unseen until treated.
Methods for Making Latent
Prints Visible.
 Chemical Methods
–  Iodine fuming
–  Ninhydrin
–  Silver Nitrate
–  Super Glue Fuming
 Powder Methods
–  Black Powder for light surfaces
–  White powder for dark surfaces
Dusting for Fingerprints
Three Classes of Fingerprints
What Is a Delta?
Loops
  60% of the worlds
population has them
  Ridges start on one
side, rise towards the
center, and return back
to the side they started
from
  Has 1 delta
  2 types of loops
•
•
Radial (thumb)
Ulnar (pinkie)
Arches
  5% of the world’s
population has them
  Start on one side,
rise towards the
center, then leave on
the other side
  No deltas
  2 Types of arches
•
•
Plain
Tented
Whorls
 35% of the worlds
population has them
 Has some ridges that
form circles or spirals
Has 2 Deltas
 4 types of whorls
•
•
•
•
Plain
Central Pocket whorl
Double Loop
Accidental whorl
Four Types of Whorls
Plain Whorl
Double Loop
Central Pocket
Whorl
Accidental
Identify the Fingerprints
Identification of Minutiae
 You must find 12
points of minutiae to
match a print from a
scene of a crime to a
person’s print
 Label each with a
number and a line to
show its location
 Make a key at the
bottom of the two
prints
Examples of Minutiae
Identification of Minutiae
1.  Bifurcation
2.  Bifurcation
3.  Bifurcation
4. Ridge Ending
5. Enclosure
6. Bifurcation
7. Bifurcation
8. Bifurcation
9. Ridge Ending
Classification of Fingerprints
 Two International Systems
 Henry System – Used in North America and
Europe
 Vucetich System – Used in Central and South
America
 Identification is based on class and ridge
patterns (minutiae) found on each
individual print
Henry Classification System
 Five different levels of classification
 Primary Classification
 Creates a fraction
 25% of the world’s population is 1/1
  RI + RR + LT + LM + LL + 1
RT RM RL LI LR 1
Whorl = 16,8,4,2,1
Arch and Loop = 0
Primary Classification Example
 A person has the following combination of
prints on their ten fingers:
RT=Arch
LT=Loop
RI=Whorl RM=Arch RR= Loop RL=Whorl
LI=Arch
LM=Whorl LR=Whorl LL=Arch
RI/RT + RR/RM + LT/RL + LM/LI + LL/LR + 1/1
16/0 + 0/0 + 0/4 + 2/0 + 0/1 + 1/1 = 19/6
 The Primary Classification is 19/6
Use the Henry System
Loop
Arch
Arch
Whorl
Arch
Loop
Whorl
Loop
Loop
Loop
Automated Fingerprint
Identification System
Scan fingerprints into a
computer database, which
transforms it into digital
minutiae. This is then
used to identify unknown
prints with several
possible matches. In the
end, a technician still
makes the final ID of the
unknown to the known
print.