what is a fingerprint? - Sewanhaka Central High School District

Report
11/13/13
• AIM: How was fingerprinting developed in
forensic science?
• DO NOW: Are fingerprints individual or class
evidence? EXPLAIN YOUR ANSWER.
• HOMEWORK: Textbook read 72-73 and 7677(Anatomy of a fingerprint). What are
friction ridges and where are they found?
Dactyloscopy
The study of fingerprints
Historically
 William Herschel—required Indians to put their fingerprints on
contracts, and also as a means of identifying prisoners
 Henry Faulds—claimed that fingerprints did not change over
time and that they could be classified for identification
 Alphonse Bertillon—proposed body measurements as a
means of identification; termed anthropometry
 Francis Galton—developed a primary classification scheme
based on loops, arches and whorls.
 Edward Richard Henry—in collaboration with Galton instituted
a numerical classification system
 Juan Vucetich—developed a fingerprint classification based on
Galton’s that is used in Spanish-speaking countries
William and Will west
Fingerprinting
Recording or Making Prints
 rolling inked prints
 primary identification number
Lifting Prints
 Black, white and fluorescent powder
 Chemicals—ninhydrin, iodine, silver nitrate, cyanoacrylate
Other Types of Prints
 Palm, lip, teeth, eye, ear, voice, shoe and footprints
What is a fingerprint?
• Skin has an outer layer (epidermis) which has
ridges projecting inward, and an inner layer
(dermis) which has projections pressing into
the spaces between ridges
• A fingerprint is a pattern made by the friction
ridges, which is left behind due to sweat and
oil that sticks to them.
• Fingerprints form during the fetal stage of
development.
http://www.smithsonianmag.com/vi
deo/Where-Do-Fingerprints-ComeFrom.html
When do they form?
• In early embryonic
development &
remain constant
What determines fingerprints?
• DNA - Genes
• & environmental
forces: pressures
within the womb and
contact with the
amniotic fluid
Formation of fingerprints
• Skin layer growth
– 3-4 month
– Middle layer of skin buckles and folds
creating the first ridges
• Creation of ridges
– fetus touches surrounding structures, exact
position in the womb and the density of
the womb's amniotic fluid determine how
every individual ridge will form
• Ridge patterns: 6 months
– The ridges on a fetus's fingertips have
formed three main patterns categorized as
arches, loops and whorls
• Fingerprint characteristics
– two common characteristics found in every
fingerprint: ridge end and bifurcation
– The sequences of ridge end and bifurcation
characteristics are different in every
fingerprint
Anatomy of Fingerprints
• Epidermis
– Outer layer of the skin
• Dermis
– Inner layer of the skin
• Dermal papillae
– Layer of cells between
the epidermis and
dermis
– Responsible for
determining the form
and pattern of the
ridges on the surface
of the skin
11
Fundamental Principles
of Fingerprints
 A fingerprint is an
individual characteristic.
 A fingerprint will remain
unchanged during an
individual’s lifetime.
 Fingerprints have general
characteristic ridge
patterns that permit them
to be systematically
classified.
Thursday 11/14/13
• AIM: How are imprints individual pieces of
evidence?
• DO NOW: Explain how fingerprints are formed
• HOMEWORK: Textbook read pages 79-80.
Answer questions 6-10 on page 100
• Wednesday hw: Textbook read 72-73 and 7677(Anatomy of a fingerprint). What are
friction ridges and where are they found?
DONOW ANSWER
• DNA controls formation of epidermis and
dermis
• The pressure on the amniotic fluid finalizes
the ridge pattern
Fingerprint Ridges
•
•
•
•
Give skin traction for picking up items.
The fine lines curve, circle, and arch.
Valleys - grooves or furrows
Hills - friction ridges
Fingerprint principle 1
• A fingerprint is an individual characteristic
• no two fingers have yet been found to posses
identical ridge characteristics
Principle 2
• Fingerprints have general ridge patterns that
permit them to be systematically classified
Fingerprint Pattern
• Pores on the ridges
• Discharge perspiration
from the sweat glands
• Sweat mixed with oil
can leave a latent
invisible fingerprint
Other Prints
 Ears—shape, length and width
 Voice—electronic pulses measured on a
spectrograph
 Foot—size of foot and toes; friction ridges on the foot
 Shoes—can be compared and identified by type of
shoe, brand, size, year of purchase, and wear pattern.
Kendall/Hunt Publishing Company
19
Other Prints
Palm—friction ridges
can be identified and
may be used against
suspects.
Other Prints
Footprints are
taken at birth as a
means of
identification of
infants.
Chapter 4
Other Prints
Lips—display several
common patterns




Short vertical lines
Short horizontal lines
Crosshatching
Branching grooves
Chapter 4
Other Prints
Teeth—bite marks
are unique and can
be used to identify
suspects. These
imprints were placed
in gum and could be
matched to crime
scene evidence.
Chapter 4
Other Prints
The blood vessel
patterns in the eye
may be unique to
individuals. They are
used today for various
security purposes.
Chapter 4
Friday 11/15/13
AIM: how are fingerprints identified?
DO NOW: List the three major
characteristics used to identify fingerprints.
Explain why each of your ten fingerprints
are different.
Chapter 4
Characteristics of fingerprints
Chapter 4
Arch
An arch has friction ridges
that enter on one side of
the finger and cross to
the other side while
rising upward in the
middle.
Types
Plain- the arch is mild
Tented- the arch is
spiked upward
Chapter 4
Plain arch
Tented arch
Loop
A loop must have one or more ridges
entering and exiting from the same
side it began.
Loops must have one delta (a“Y”
pattern from diverging ridges)
Types
Radial--opens toward the thumb
Ulnar--opens toward the “pinky”
(little finger)
Which type of loop is this, if on the
right hand? Left hand?
deltaΔ
Whorl
A Whorl has a minimum of 2
deltas.
Types
 Plain- 2 symmetric deltas and a
complete ridge circuit (circular in
pattern)
 Central Pocket- 2 asymmetric deltas,
one side appears to be stretched
 Double Loop- 2 loops and 2 deltas
 Accidental- a whorl that does not fit
the 3 above pattern types
Plain whorl
31
Central Pocket Whorl
32
Double Loop (whorl)
33
Accidental whorl
34
http://on.aol.com/video/howto-determine-fingerprintpatterns-72416331
Kendall/Hunt Publishing Company
35
• White lines in ridge
patterns represent
diet pattern.
• Many white lines
indicate celiac
disease
36
Determining fetal environment
• The more symmetrical your fingerprints the
more stable the amniotic environment
Kendall/Hunt Publishing Company
37
Monday 11/18/13
• AIM: how are fingerprints analyzed?
• DO NOW: 1- What are the 3 general fingerprint
patterns?
2-Explain the roll of the delta in fingerprint
identification
HOMEWORK: Using the class information, create a
bar graph of the % of fingerprint patterns
2- Do the classroom % match the national average?
Kendall/Hunt Publishing Company
38
Loops
• Must have one delta
40
Whorls: 2 deltas
Arches NO deltas
Human population fingerprint
distribution
• Loops: 65%
• Whorls: 30%
• Arches: 5%
FINGERPRINT IDENTIFICATION
On your computer paper
Thumb
Right Hand
Ridge pattern
LeftHand
Ridge pattern
Index
Middle
Ring
Pinky
Thursday 11/21/13
• AIM: how are fingerprints compared?
HOMEWORK:Textbook pg 100 questions 3-10.
write out the question followed by the answer
Identify each fingerprint pattern.
Right Hand
Left Hand
Right Hand
Right Hand
Left Hand
Fingerprint Identification
• The uniqueness of a fingerprint can be
determined by the pattern of ridges and
valleys as well as the minutiae points.
• Minutiae points are local ridge characteristics
that occur at either a ridge bifurcation or a
ridge ending.
49
Ridge Characteristics
Minutiae—characteristics of ridge patterns










Ridge ending
Short ridge
Dot or fragment
Bifurcation
Double bifurcation
Trifurcation
Bridge
Island
Enclosure
Spur
Kendall/Hunt Publishing Company
50
RIDGE CHARACTERISTICS (Minutiae)
COMMON
Ending Ridge
OCCASIONAL
RARE
Fingerprint Basics (minutiae)
Bifurcation
dot
Ridge ending
Double bifurcation
52
Fingerprint Basics (minutiae)
Opposed bifurcation
Island (short ridge)
Hook (spur)
Lake (enclosure)
53
Fingerprint Basics (minutiae)
Bridge
Ridge crossing
trifurcation
Opposed
bifurcation/ridge
ending)
54
RIDGE CHARACTERISTICS MAGNIFIED
11
1
10
2
9
3
8
4
5
7
Points 1, 2, 4, 5 are Ending Ridges
Points 8, 10, 11 are Bifurcations
Point 7 Short Ridge
6
Points 3 and 9 are Dots
Point 6 is an Enclosure
(ISLAND)
Fingerprint Minutiae
Kendall/Hunt Publishing Company
56
How are fingerprints compared?
A. Fingerprints are compared by noting the ridge pattern
on two prints to determine whether or not they match.
B. The minutiae characteristics are then compared
C. An identification is established when a number of
these characteristics occupy the same relative position
on the two prints.
Comparison
There are no legal
requirements in the
United States on the
number of points.
Generally, criminal
courts will accept 8 to
12 points of similarity.
Activity: Sticky Fingers
Fingerprints
Modern Fingerprint Analysis

Computer system stores patterns and
minutiae of prints

AFIS: automated
fingerprint identification
system
FINGERPRINT IDENTIFICATION
Primary Classification
The Henry—FBI Classification
Each finger is given a point value
right
left
Kendall/Hunt Publishing Company
62
Primary Classification
Assign the number of points for each finger that has a
whorl and substitute into the equation:
right
index
right
ring
left
thumb
left
left
middle little + 1
=
right
thumb
right
right
middle little
left
left
index ring
+1
That number is your primary classification number
Kendall/Hunt Publishing Company
63
Arches
Arches are the simplest type of fingerprints that are formed
by ridges that enter on one side of the print and exit on the
other. No deltas are present.
Spike or “tent”
Plain Arch
Ridges enter on one side and
exit on the other side.
Tented Arches
Similar to the plain arch,
but has a spike in the center.
Loops
Loops must have one delta and one or more ridges that enter and
leave on the same side. These patterns are named for their
positions related to the radius and ulna bones.
Delta
Ulnar Loop (Right
Thumb)
Loop opens toward
right or the ulna bone.
Radial Loop (Right
Thumb)
Loop opens toward the
left or the radial bone.
NOTE: On the left hand, a loop that opens to the left would be an ulnar
loop, while one that opens to the right would be a radial loop.
Whorls
Whorls have at least one ridge that makes (or tends to make) a
complete circuit. They also have at least two deltas. If a print has
more than two deltas, it is most likely an accidental.
Plain
Whorl
Central
Pocket
Whorl
Draw a line between the two deltas in the plain and central pocket
whorls. If some of the curved ridges touch the line, it is a plain
whorl. If none of the center core touches the line, it is a central
pocket whorl.
Whorls – Part 2
Double Loop Whorl
Accidental Whorl
Delta
Delta
Double loop whorls are
made up of any two loops
combined into one print.
Accidental whorls contain two
or
more
patterns
(not
including the plain arch), or
does not clearly fall under any
of the other categories.
WHAT IS A FINGERPRINT?
A fingerprint is a pattern comprised of ridges and
valleys.
A Ridge – is a high.
A Valley – is a depression or low.
Friction ridges are also found on our palms, feet
and toes.
Ridge
Valley
Anatomy of fingerprints
• Finger touches a surface
–Perspiration
–Oils from hairy portions of the
body
–Transferred onto surface
• Leaves fingerprint
70
What is a Fingerprint?
• Skin has an outer layer (epidermis) which has ridges
projecting inward, and an inner layer (dermis) which
has projections pressing into the spaces between
ridges
• A fingerprint is a pattern made by the friction ridges,
which is left behind due to sweat and oil that sticks
to them.
• Fingerprints form during the fetal stage of
development.
71
There are 3 types of fingerprints
Visible – left by dirt, grease, blood, etc.
1.

Does not need processing
There are 3 types of fingerprints
Impression – indentation in soft material
(butter, putty, tar, etc.)
2.

Does not need processing
There are 3 types of fingerprints
3.
Latent – requires processing to make
visible and suitable for analysis
What are the invisible components?
Multiple sweat glands secrete onto fingers,
palms, etc.
Sweat contains:


Inorganic ions (Na+, Cl -)
Proteins, amino acids


Lipids
Other
Lifting Latent Prints
Developing a print requires chemicals that react with
secretions that cause the print to stand out
against its background. It may be necessary to
attempt more than one technique, done in a
particular order so as not to destroy the print.
Powders--adhere to both water and fatty deposits.
Choose a color to contrast the background.
Iodine--fumes react with oils and fats to produce a
temporary yellow brown reaction.
76
Physical Development: Dusting

Apply powder to latent print or area.

Powder adheres to print.
Brush and Powder
Physical Development: Dusting

Apply powder to latent print or area.

Powder adheres to print.
Magnetic Brush
and Powder
Lifting Latent Prints (cont)
Ninhydrin--reacts with amino acids to produce a purple
reaction.
Silver nitrate--react with chlorides to form silver chloride,
a material which turns gray when exposed to light.
Cyanoacrylate--”super glue” fumes react with water and
other fingerprint constituents to form a hard,
whitish deposit.
 In modern labs and criminal investigations, lasers and alternative
light sources are used to view latent fingerprints. It was first
used by the FBI in 1978. Since lasers can damage the retina of
the eye, special precautions must be taken and a filter used.
79
Chemical Development:
Silver Nitrate
1.


No longer used (messy, not sensitive)
Silver reacts with Cl - ions in print
Fingerprints > Analysis
Chemical Development:
Iodine Fuming
2.



Iodine sublimes
(solid → gas)
Iodine reacts with lipid
components; becomes
trapped in the print.
Fuming wand or chamber
Dirty Brown Color
Iodine Fingerprint
82
Chemical Development:
Ninhydrin
3.



Reacts with amino acids; purple color
Painted or sprayed on area
Heated to react
Ninhydrin Fingerprint
84
Chemical Development:
Super glue fuming
4.



Fumes with heat or base (NaOH)
Fumed in cabinets
Off-white print
Cyanoacrylate Fingerprints
86
Chemical Development:
Ninhydrin and super glue prints can be
further processed:


Dusted
Chemically treated to
fluoresce (using laser
or alternative light)

similar documents