Transcript File

Bell Work for Tuesday, March 3
• Finish your notes and vocabulary from
yesterday-Ch. 6!
• Define porous vs. nonporous surfaces
• Start thinking about questions you would
like to ask to our officer on Friday!
Means of Human Identification
• Alphonse Bertillon
– 1st systematic attempt at identification
• Anthropometry – a system of precise body
measurements (11+, including height, reach,
width of head, length of left foot)
• Also used full length and profile
photographs
The Chinese
• Used fingerprints as royal seals 3,000 years
ago.
• Used in document validation
William Herschel
• English civil servant stationed in India
• Required natives to sign contracts with an
imprint of their right hand
• Not sure if this was used as a means of
identification or method of maintining
contract according to Hindi Tradition
Henry Fauld
• Scottish Physician based in Japan
• One of 1st to publish views on the potential
use of fingerprints as a means of
identification
• Cited case where thief left print in a freshly
whitewashed wall and was convicted
because of it
Francis Galton
• Published book on Fingerprints with same
title (1892)
• Discussed the anatomy of fingerprints and
suggested methods for recording them.
• Assigned the 3 pattern types
• Whorls, loops, arches
• Convincingly demonstrated that no 2 prints
were alike
Dr. Juan Vucetich
• Argentinean police officer
• Devised a workable classification system in
1891
• System has been revised and is still used in
most Spanish-speaking countries today
Sir Edward Richard Henry
• In 1897, proposed another classification
system
• Adopted by Scotland Yard
• Used by the US as the classification system
to file and analyze fingerprints
The FBI
• In 1924, fingerprint records of the Bureau of
Investigation and Leavenworth Prison were
merged to form the nucleus of the
identification records
• Currently has the largest collection of
fingerprints in the world
st
1
Principle:
• A fingerprint is an individual characteristic;
no 2 fingers have yet been found to possess
identical ridge characteristics
• Even identical twins will have different
prints
• Ridge characteristics – minutiae, identifying
characteristics within the fingerprint that
must match up for identification
Individual Ridge Characteristics
•
•
•
•
•
Bifurcation
Short Ridge
Enclosure
Dot (island)
Ridge Ending
How many must match?
• Since most prints left at the scene are not
complete, partial prints must be matched to
prove identification
• It has been suggested that at least 8 – 16
characteristics must match for a conclusive
result
nd
2
Principle
• A fingerprint will remain unchanged during
an individual’s lifetime
• Even if prints are damaged, enough remains
to provide match
• Latent Prints – a fingerprint made by the
deposit of oils and or perspiration. Invisible
to the naked eye
rd
3
principle
• Fingerprints have general ridge patterns that
permit them to be systematically classified
Patterns
T. Trimpe 2006 http://sciencespot.net
Fingerprint Principles
According to criminal investigators, fingerprints follow
3 fundamental principles:
• A fingerprint is an individual characteristic; no two
people have been found with the exact same
fingerprint pattern.
• A fingerprint pattern will remain unchanged for the
life of an individual; however, the print itself may
change due to permanent scars and skin diseases.
• Fingerprints have general characteristic ridge patterns
that allow them to be systematically identified.
Fingerprint Classes
There are 3 specific classes for all fingerprints based
upon their visual pattern: arches, loops, and whorls.
Each group is divided into smaller groups
as seen in the lists below.
Arch
Plain arch
Tented arch
Loop
Radial Loop
Ulnar loop
Whorl
Plain whorl
Central pocket whorl
Double loop whorl
Accidentical
Interesting Info
Fingerprint Factoid:
60% of people have loops, 35% have whorls,
and 5% have arches
Did you know?
Dactyloscopy is the study of fingerprint identification.
Police investigators are experts in collecting
“dactylograms”, otherwise known as fingerprints.
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.
Arches
• Friction ridges that enter on one side of the
finger and cross to the other side while
rising up in the middle.
– Plain – has mild bulging
– Tented – has ridge that looks like a pole
pushing up in the middle (taller).
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.
Loop: most common pattern
• Depends on which hand made the print (left or
right)
• Has one or more ridges entering from one side,
curving, and then leaving from the same side.
• All loops have one delta (triangle shaped ridge
pattern)
• If loop points towards thumb – ulnar loop
• If loop points away from thumb – 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.
Whorls
• Have minimum of 2 deltas
• 4 sub groups:
–
–
–
–
Plain – 2 deltas and complete ridge circuit
Central pocket – one delta is larger than other
Double – 2 loops in a yin-yang shape
Accidental – deltas far spaced, mix of 2
patterns that do not conform to other standards.
Identify each fingerprint pattern.
Right Hand
Left Hand
Right Hand
Right Hand
Left Hand
Fingerprint Classification
• Primary Classification: Part of the Henry
system still used by the FBI
• Fingers are paired up and patterns are given
specific values
• Whole records of all 10 fingers are
recorded.
What about single prints?
• How often at a crime scene does a criminal
leave all ten fingerprints in a line?
• It became too bulky and tedious to match
prints by hand
Now…
• Law Enforcement Agencies use a computer
database of prints called AFIS.
• AFIS 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 branching of ridges into 2 ridges
• AFIS makes no final decision on the print, leaving
that determination to the examiner.
• AFIS has substantially reduced the amount of time
required to match prints (20 min vs. proj. 67
years)
Methods of detecting fingerprints
• Visible prints: Made by fingers touching a surface
after the ridges have been in contact with a
colored material (blood, paint, grease, ink).
• Plastic Prints: ridge impressions on a soft material
(putty, soap, wax, dust)
• Latent prints : caused by the transfer of body
perspiration or oils present on finger ridges to the
surface of an object.
Types of surface determine
process
• Hard, nonabsorbent surfaces: glue fuming
or powders
• Soft and porous: chemical treatments
Detection of Latent prints
(locating)
• RUVIS: Reflected Ultraviolet Imaging
System
– Can locate prints without the aid of chemical or
powder treatments
– UV Light is shown at the surface and reflected
back by the print making the print visible.
Powders
• Readily adhere to perspiration residues and
body oil deposits
• Examiners choose color that best contrasts
with surface color
• Magnetic sensitive powders are applied
with a magnet, not a brush – no smearing
• Fluorescent powders- used on colored
surfaces to develop latent prints.
Chemical methods:
• Glue fuming: cyanoacrylate (Super Glue) is heated
and binds to amino acids
• Iodine fuming : solid iodine is heated binds to
print (not permanent)
• Ninhydrin: sprayed on surface and developed
using steam, turns purple in amino acids.
(permanent and good for old evidence)
• Physical developer: used in combination with
other chemicals to help fix a print.
The Henry System
• Adopted by Scotland Yard in 1901
• Converted ridge patterns on all 10 fingers
into a series of letters and numbers arranged
in the form of a fraction.
• Could only be used in small databases
(100,000 records or less)
Warm Up
• Start studying the sheet I gave you as well
as your notes from yesterday for our quiz
today!
It’s time to make
some prints!
Avoid
Partial
Prints
GOOD PRINT
Get as much of the top part
of your finger as possible!
Directions
1st – Roll the “pad” portion of your thumb over the
ink pad from the left side of your thumb to the
right. You do not have to push down really hard!
2nd – Roll the “pad” portion of your thumb from the left side of
your thumb to the right in the correct box on your paper to make a
thumbprint.
3rd – Continue this process to make a fingerprint of all ten fingers
on the “My Prints” worksheet.
4th –Use your notes and a magnifying lens to help you figure out
what type of pattern is found in each of your fingerprints. Label
each one with the pattern’s name and minimum 3 minutae