Transcript Fingerprints - Loyola Blakefield

Fingerprints
Chapter 14
History of Fingerprinting
Scientist
Alphonse
Bertillon
Henry Fauld
Francis Galton
Dr. Juan Vucetich
Sir Richard
Edward Henry
Date
Contribution to Forensics
(approximate)
History of Fingerprinting
Alphonse Bertillon
• 1883 – First systematic
attempt at personal
identification
• Used portrait parlé - verbal
description of perpetrator’s
physical characteristics and
dress provided by an
eyewitness
• And used anthropometry –
a system of precise body
measurements
• System used for over two
decades
History of Fingerprinting
Henry Fauld
• 1880 – Scottish physician
published articles suggesting
that skin ridge patterns could
be important in identification
of criminals
– Explained how fingerprints
were used to solve a crime
– Offered to help set up system
at Scotland Yard; offered
rejected
History of Fingerprinting
Francis Galton
• 1892 – Published the textbook
Fingerprints
– Discussed anatomy of fingerprint
and methods of recording
– Introduced the three patterns –
loop, whorl, and arch
– Demonstrated that no two prints
were identical and that prints do
not change over a lifetime
• British government adopted
fingerprinting as a supplement
to the Bertillon system
History of Fingerprinting
Dr. Juan Vucetich
• 1891 – Argentinian police officer
• Devised a classification system for prints
so that they can be filed and searched
easily
• Although revised, it is still used in many
Spanish speaking countries
History of Fingerprinting
Sir Edward Richard Henry
• 1897
– Proposed another type of classification
system adopted by Scotland Yards
– Most English speaking countries use a
modified version
History of Fingerprinting
Will West
• 1903
• Proved Bertillon’s system inaccurate
• Convict arrived at prison to find another William
West with the same body measurements and
similar physical characteristics
• Fingerprints were use to distinguish prisoners
History of Fingerprints
New York City Civil Service Commission
• 1901
• First systematic and official use of
fingerprints for personal identification
• Used to certify all civil service applications
Fundamental Principles of Fingerprints
A Fingerprint is an Individual Characteristic; No
Two Fingerprints Have Yet Been Found to
Possess Identical Ridge Characteristics.
• Galton calculated the possible
existence of 64 billion different
fingerprints!
• Ridge Characteristics, also known as
minutiae, are ridge endings, enclosures,
and other ridge details that must match in
two fingerprints in order for their common
origin to be established
• In judicial proceedings, a point-by-point
comparison must be demonstrated
• There are as many as 150 ridge
characteristics on the average fingerprint
Fundamental Principles of Fingerprints
A Fingerprint Will Remain Unchanged
During an Individual’s Lifetime
• The pattern of ridges
determined by the dermal
papillae, the boundary
between the first two layers
of skin
• Pores are present on the
top layer releasing sweat
and oil – this can be
transferred to a surface
when touched leaving an
invisible impression – latent
fingerprints
Fundamental Principles of Fingerprints
Fingerprints Have General Ridge Patterns that
Permit Them to be Systematically Classified.
•
All fingerprints are divided into three classes on the
basis of their general pattern: loops, whorls, and
arches
Refer to Fingerprinting 101 to
identify the various classes of
fingerprints.
Ridge Characteristics
• The individuality of a fingerprint is not
determined by its general shape but by
careful study of its ridge characteristics or
its minutiae
• No two fingers have yet been found to
possess identical ridge characteristics
Basic and composite ridge characteristics (minutiae)
Minutiae
Example
Minutiae
ridge ending
bridge
bifurcation
double bifurcation
dot
trifurcation
island (short ridge)
opposed bifurcations
lake (enclosure)
ridge crossing
hook (spur)
opposed
bifurcation/ridge
ending
Example
Ridge Characteristics
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•
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•
•
•
•
•
•
Ridge Dots
Bifurcations
Trifurcations
Ending Ridge
Ridge Crossing
Enclosures (Lakes)
Short Ridges (Islands)
Spurs (Hooks)
Bridges
Ridge Dots
• An isolated ridge unit whose length
approximates its width in size
Bifurcations
The point at which one friction ridge divides
into two friction ridges
Double Bifurcation
Opposed Bifurcation
Trifurcations
• The point at which one friction ridge
divides into three friction ridges
Ending Ridge
• A single friction ridge that terminates within
the friction ridge structure
Ridge Crossing
•
A point where two ridge units
intersect
Enclosures (Lakes)
• A single friction ridge that bifurcates and
rejoins after a short course and continues
as a single friction ridge
Short Ridges (Islands)
• Friction ridges of varying lengths
Spurs (Hooks)
• A bifurcation with one short ridge
branching off a longer ridge
Bridges
• A connecting friction ridge between
parallel running ridges, generally right
angles
Classification of Fingerprints
• System used by FBI converts ridge
patterns on all 10 fingers into numbers in
the form of a fraction
• Fingerprint cards can be classified into
1024 groups
• The presence or absence of a whorl
pattern is the basis for the determination of
the primary classification
Classification
1.
Fingers are paired in the following sequence:
R. Index
R. Ring
L. Thumb
L. Middle
L. Little
R. Thumb
R. Middle
R. Little
L. Index
L. Ring
2.
If a whorl pattern is found on any finger in the first pair, it is
assigned a value of 16; on the second pair, a value of 8; on the
third pair, a value of 4; on the fourth pair, a value of 2; and on the
fifth pair, a value of 1. Any finger have an arch or loop is assigned
a value of 0.
3.
Add all the values for the 10 fingers and then add 1 to both the
numerator and denominator.
4.
The fraction obtained is the classification.
For example:
16 + 0 + 0 + 0 + 0 + 1
17
=
0 + 8 + 0 + 0 + 0 + 1
9
Automated Fingerprint Identification
System
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The AFIS (Automated Fingerprint Identification
System) uses automatic scanning devices that
convert the image of a fingerprint into digital minutiae
that contain data showing ridges at their points of
termination and the branching of ridges into two ridges
(bifurcations).
AFIS has brought about a fundamental change to the
way criminal investigators operate, allowing them to
spend less time developing suspect lists and more
time investigating the suspects generated by the
computer.
Types of Prints
 Visible Prints are made when
the fingers touch a surface
after the ridges have been in
contact with a colored
material such as blood, paint,
grease or ink.
 Plastic prints are ridge
impressions left on a soft
material such as putty, wax,
soap or dust.
 Latent Prints are impressions
caused by the transfer of
body perspiration or oils
present on finger ridges to
the surface of an object.
Locating Latent Prints
 Locating latent prints requires the use of
techniques that will make the prints visible.
 Latent prints on hard and nonabsorbent
surfaces (e.g., glass, mirror, tile and painted
surfaces require the use of powders and/or
Super Glue to make the prints visible.
 Prints on soft or porous material (e.g., paper,
cardboard, cloth) generally require treatment
with one or more chemicals to make them
visible.
Methods of Detecting Fingerprints
• Each group will be assigned one of the
methods used for detecting fingerprints.
• Read about the method in your book on
pages 417-424 and answer the following
questions in your notes:
– What type of print does it detect?
– On which type of surface does it work best?
– What is the process used to visualize the
prints and retrieve them?
• Type up your notes in a few concise lines
on word document to present to the class.
RUVIS
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Sometimes the most difficult aspect of fingerprint
examination can be the location of the print.
Recent advances in fingerprint technology have led to the
development of an ultraviolet image converter for the
purpose of detecting latent prints.
This device, called the Reflected Ultraviolet Imaging
System (RUVIS), can locate prints on most nonabsorbent
surfaces without the aid of chemical or powder treatments.
RUVIS detects the print in its natural state by aiming UV
light at the surface suspected of containing prints. When the
UV light strikes the fingerprint, the light is reflected back to
the to the viewer, differentiating the print from its
background surface.
The transmitted UV light is then converted into visible light
by an image intensifier. Once located in this manner, the
crime-scene investigator can develop the print in the most
appropriate manner.
Other techniques for lifting prints
 Iodine Fuming is a technique for
visualizing latent fingerprints by exposing
them to iodine vapors.
 Sublimation is a physical change from the
solid directly to the gas state.
 Ninhydrin is a chemical reagent used to
develop latent fingerprints on porous
material by reacting with amino acids in
perspiration.
Other techniques for lifting prints
•
•
Physical developer: a silver-based
reagent formulated to develop latent
fingerprints on porous surfaces.
Super Glue Fuming: A technique used for
visualizing latent fingerprints on nonporous surfaces by exposing them to
cyanoacrylate vapors; named for the
commercial product “Super Glue”.
Digital Imaging
 Digital Imaging is the process by which a
picture is converted into a digital file.
 When fingerprints are lifted from a crime
scene, they are often not in perfect condition.
This makes their analysis very difficult.
 With the help of digital imaging software,
fingerprints can now be enhanced for the most
accurate and comprehensive analysis.