Transcript File

WARM UP 1 (8pts)
1.
2.
List 3 things you know about fingerprints
List 3 things you want to learn about
fingerprints
THINK:
3. When would fingerprints be useful in
forensics?
4. What do you think actually makes the
fingerprint left behind?
CH 6 NOTES #1
2/18
Brief History of Fingerprinting
Fingerprints 1st used for signatures
 on pottery in China
Indians in US for contracts.

Bertillon System (Anthropometrics)
•
•
identification system using
body measurements
• Bertillon System had three components
(11 total measurements)
1. Measurements of the MAIN BODY
•
•
Whole height
Reach (finger to finger)
Trunk (sitting up)
2. Measurements of the HEAD
•
•
•
Maximum length front-to-rear
Breadth
Length & diameter of the right ear
3. Measurements of the ARMS and LEGS
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•
•
Length of left foot
Length of left middle & little fingers
Length of left forearm from elbow to the tip of the middle finger
Added Features
•Eventually a pair of photos were added to the
profile
•Attached to the photos was a verbal description
of the person and any:
•birthmarks
•scars
•tattoos
•deformities
Problems:
1. People’s bones changes throughout life.
2. People may have the same set of
measurements.
3. People take measurements differently.
4. Time consuming to do.
5. Doesn’t help solve crimes well.
The Will West Case
In 1903, a prisoner named Will West was brought to
Leavenworth Federal Penitentiary.
After being booked, they noticed that his Bertillon
measurements & photograph appeared to be identical to
another prisoner (William West) serving a life sentence
for murder.
Although the two men were similar enough to be identical
twins, they were not related
– 1910 – police forces started to use this
when arresting criminals
– 1924 FBI started collection of
fingerprints from all criminals arrests
(currently 250 million sets from around
the world)
What Are Fingerprints?
•A reproduction of skin friction ridges
•Found on the hands, feet, lips
FINGERPRINT ANATOMY
Skin is composed of 2 layers:
epidermis and dermis
Epidermis has raises called skin friction
ridges
Purpose: gripping
•Dermal papillae are
bumps in the dermis
that push up and
make the ridges
•Each ridge has
sweat pores
3 Fundamental Principles of Fingerprints
1. Fingerprints are unique.
•no two fingers have been found to possess identical
ridge characteristics
2. Fingerprints never change.
•Develop in fetus at 4.5 months
•Never change, only get larger
3. Fingerprints have ridge patterns
3 main types
Average of 150 minutae patterns per finger
In court – show at least 12 matches
– 1999 US vs Byron Mitchell- allowed
fingerprints to be used in court
TYPES OF PRINTS:
1.
MOLDED PRINTS – made by finger
pressing against a soft substance
EX: putty, soap, wax, gum, food, etc.
2.
VISIBLE PRINTS: left by finger that
touched colored material
EX: blood, paint, ink, chalk, mud, dust, etc.
3.
LATENT PRINT – any
print left behind that is
“invisible”
What makes them?
a. Sweat : Water, salts, amino
acids, lipids, ammonia
b. Oils
c. Particles (EX: dirt)
Ridge characteristics (minutiae points)
Island
Bifurication
Enclosure
Ridge ending
Ridge crossing
Short Ridge
Delta
A single fingerprint may have as many as 100 or more
identification points that can be used for identification
purposes
WARM UP 5/23
1.
2.
3.
4.
5.
6.
What was the Bertillon Method?
What are the 3 principles of fingerprints?
Who do you think would be considered “the
father of fingerprinting”?
Name 3 problems with Bertillon Method.
What are dermal papillae?
What are the 3 different print types?
Common Types of Fingerprints
Three main groups:
LOOPS
WHORLS
ARCHES
Loops
•60- 65% of fingerprints are
loops
•A loop must have one or
more ridges entering from
one side of the print,
curving & exiting from the
same side
•Loops have 1 delta
Whorls
•About 30% - 35% of
fingerprints are whorls
•Whorl patterns must have at
least two deltas
Types of Whorls
4 groups of whorls:
1. Plain
2. Central Pocket
3. Double Loop
4. Accidental
Plain Whorl
•Inner area of pattern forms circles
Central Pocket Whorl
•Circular pattern is off-centered
Double Loop Whorls
•Looks like a sideways “S”
Accidental Whorl
•Doesn’t fit any of the other types
There is a long history in India and China of the use of
fingerprints as indications or attributes or character traits.
Folk lore from both India and China have traditions of
reading certain attributes or abilities from fingerprints.
Before we become amused at the tendency to find
significance in the counted number of prints, we note that
such an approach is often used in scientific studies of the
searching for meaningful relationships of fingerprints as
genetic and/or chronic health markers. So while the
conclusions drawn in Chinese and Hindu folk ways may be
quaint, their methods of analysis still persist.
Chinese folk fingerprint formula(21)
One whorl indicates poverty
Two whorls indicate riches
Three and four whorls good aspect to open a
pawnshop
Five whorls for a mediator
Six whorls for a thief;
Seven whorls very bad, indicates catastrophes;
Eight whorls and you will eat chaff;
Nine whorls with a loop and there will be no work for
you to do, and plenty of food till old age;
HINDU: When the loop is found on:
One finger, the subject is happy;
But on two Fingers, it is not a favorable sign; and
On three fingers it is a bad sign;
When found only on four fingers it is not a good
omen; and when found on five fingers it is not
auspicious;
But it is a sign of prowess if found on six fingers; and
When placed on seven fingers live in kingly comfort;
While on eight fingers one is as noble as a king; and
On nine fingers one must live like a king;
Arches
•About 5% of all fingerprints
•There are no deltas
Two types of arches
1. plain arch
2. tented arch
Plain Arch
lines come in one side of the print and
exit the other side
Tented Arch
•Like a plain arch but it rises at a steep
angle
Primary Classification (Henry System)
Determined on the presence or absence of the whorl
pattern
Presence of a whorl pattern is given a numerical value
that depends on the finger on which it occurs
•other patterns are given a value of zero
25% population is 1/1 OR no whorls on any fingers
FORMULA:
R.index + R.ring + L.thumb + L.middle + L.little +1
R.thumb + R.middle + R.little + L.index + L.ring + 1
(16/0)
(8/0)
(4/0)
(2/0)
(1/0)
+1
10 Fingerprint Classification
Good for having all prints on file
Can narrow down fast if all prints were found at
the scene
FBI system of having all prints in categories
Crime Scene Fingerprints
•Fingerprints found at a crime scene are often
incomplete or less than perfect
•An inked (known) print is compared to a latent
(unknown) print
•Ridge characteristics must be of the same shape &
type, occupying the same relative position
•Must be an adequate # of indistinguishable features
with no unexplainable differences to be used in court
– at least 12 characteristics (though no set number
by law)