Fingerprints
History of Fingerprinting
• People have always wanted a full proof way to
identify someone.
• The first system was created by Alphonse
Bertillon (1883)
• Used a detailed description plus full length and
profile photographs.
• Also used precise body measurements
• This included height, reach, width of head &
length of left foot.
History of Fingerprinting
• Police used Bertillon's method for 20 years
Early use of fingerprints
• Chinese used fingerprints to sign legal
documents 3000 years ago
• It was only used in a few places, so no system
for identification was created.
• Around 1880 William Herschel started using
handprints for I.D. on contracts in India.
History of Fingerprinting
• Henry Fauld was a doctor in Japan who wrote
an article on how fingerprints could be use for
identification.
• He thought that ridge patterns in the skin
could be used to identify criminals.
• Wanted to pay for a fingerprint bureau at
Scotland Yard.
• He was turned down.
History of fingerprinting
• 1892 – Francis Galton published the textbook
“fingerprints”
• It suggested methods for recording them
• Found three types of fingerprint patterns
• Loops, whorls and arches
• Showed that no two people had the same
fingerprints.
• Also showed they did not change with time.
History of Fingerprinting
Two classification systems for fingerprinting
were created.
1) Dr. Juan Vucetich – argentine police officer
- His system is still used in most Spanish
speaking countries
2) Sir Edmund Richard Henry
- His system is used in most English speaking
countries.
Adoption of Fingerprinting
• Bertillon’s body measurement system had
problems.
• The measurements were not always accurate
• 1903 – convict Will West is sent to Fort
Leavenworth Prison.
• There was already a Will West in the prison.
• The two men looked identical and had
identical measurements.
Adoption of Fingerprinting
• You could only tell them apart by fingerprints
The first official use of fingerprinting was in New
York city in 1901.
• Was used to certify civil service applicants
• Police, firemen, postmen, etc.
1924 – FBI and Leavenworth prison records put
together to make a fingerprint database
Adoption of Fingerprinting
• FBI has the largest collection of fingerprints in
the world.
By WWI (1912), all of Europe was using
fingerprinting for identification.
Fundamental Principles
of Fingerprints
There are three basic principles
1) No two fingerprints have yet been found to
possess identical ridge characteristics.
• About 64 billion different possibilities for a
fingerprint.
• Odd extremely small two people would have
identical prints.
• In 110 years, no two have been identical
Fundamental Principles
of Fingerprints
• It is based on ridge characteristics
• = ridge endings, bifurcations, enclosures and
other ridge details which must match in two
fingerprints to establish a common origin.
• Not only do the parts of he ridges have to
match, they must be in the exact same
location on the finger.
• In court, a point by point comparison is made,
using charts, numbers and descriptions.
Fundamental Principles
of Fingerprints
Fundamental Principles
of Fingerprints
• Full prints are easy to identify
• Up to 150 individual ridge characteristics
• Most crime scene prints are partial prints or
smudges.
• Experts disagree as to how many ridge
characteristics are needed to identify
someone.
• Ranges from 8 - 16
Fundamental Principles
of Fingerprints
• Fingerprint identification is entirely dependent
on the experience and knowledge of experts.
Fundamental Principles
of Fingerprints
2) A fingerprint remains unchanged during an
individual’s lifetime.
• Fingers and thumbs, palms and soles of feet
have friction ridges for better grip.
• The shape of these skin ridges are what we
see when we look at fingerprints.
Fundamental Principles
of Fingerprints
Skin
• Made of several layers of cells
1) Epidermis – outermost layer
2) Dermis – inner layer
3) Dermal papillae – layer between dermis and
epidermis
- This layer makes the fingerprints.
- This layer develops in the fetus and never
changes
Fundamental Principles
of Fingerprints
Fundamental Principles
of Fingerprints
• Each skin ridge has a single row of sweat gland
pores.
• This sweat and oil is what is left behind as a
fingerprint.
• Latent fingerprint = an invisible fingerprint
made by deposits of oil and/or sweat.
Fundamental Principles
• Criminals try to change their fingerprints
• If you go down far enough, it will leave a scar
in the dermal papillae
• This gives us another way to identify the
person
• John Dillinger was a famous mob boss.
• He dipped his fingers in acid to get rid of his
fingerprints.
• When he died, he was identified by his
fingerprints.
Fundamental Principles
3) Fingerprints have general ridge patterns that
permit them to be systematically classified.
• There are three general patterns of
fingerprints
• Loops, whorls and arches
• 60 – 65% of people have loops
• 30 – 35% of people have whorls
• About 5% of people have arches
Fundamental Principles
Loops – have ridge lines that enter from one
side of the pattern and curve around to exit
from the same side of the pattern.
Fundamental Principles
• If the loop opens toward the little finger, it is
called an ulnar loop.
• If it opens toward the thumb, it is a radial
loop.
• A type line is ridges that peal away from the
loop.
• A delta is when the type line and loop form a
tent shape.
• The core is the center of the loop.
Fundamental Principles
Whorl – ridge patterns that are generally
rounded or circular and have two deltas.
Fundamental Principles
Four types of Whorls
1) Plain whorls have at least one ridge that
makes a complete circle.
• If you draw a line between the two deltas and
they touch a ridge.
2) Central pocket whorl – has at least one ridge
that makes a complete circle.
• If the line between the deltas does not touch
a ridge line.
Fundamental Principles
3) Double Loop – two loops in a fingerprint
4) Accidental – a combination of forms except
for the plain arch.
Fundamental Principles
Arches – don’t have type lines, deltas or cores
• Least common type of fingerprint
1) Plain arch – starts on one side of the finger,
makes an arch, goes out the other side.
2) Tented arch – same as a plain arch, but
comes to a point at the top.
Fundamental Principles
AFIS
• AFIS = Automated Fingerprint Identification
System
• The Henry system was not easy to use or to
store information.
• Until computers, it was the best we had.
• 1970 – AFIS created – computerized
identification of fingerprints.
• 1999 – IAFIS – Integrated AFIS
- This links all 50 states’ AFIS databases with the
FBI’s.
- Nearly 50 million fingerprints in the system
AFIS
• How AFIS works
• We scan and digitally encode fingerprints
• It puts markers on loops, whorls, arches, ridge
endings and bifurcations.
• Bifurcation = branching of one ridge into two
ridges
• It shows exactly where on the finger each
marker is.
• Can check 500,000 ten finger prints in less
than a second.
AFIS
AFIS
• It has a scrolling system and will kick out a list
of prints that most closely match the sample
• An expert in fingerprints will make the final
decision.
• In No Suspect cases in San Francisco, it
identified 1001 people out of 5514 cases (18%
• If done manually, it averaged 8%
• Systems will automatically filter out
imperfections.
• It will enhance the image and create a
computer image of the print.
AFIS
• The computer print and the suspect’s print are
compared side by side by an expert.
• We no longer use Ink for fingerprints in most
places.
• We now use LiveScan
• This digitally scan fingers and palms and puts
them into AFIS.
• It only takes minutes to see if they match any
other crimes.
AFIS
• Problems with AFIS
• Latent prints may not get a hit because the file
print is poor.
• Have to do manual comparisons if this happens
• AFIS systems are made by several companies
• All of them do the same thing, but don’t do it
in the same way.
• Have different measuring systems & different
features
• They can send information to the FBI, but
maybe not to other states.
Detecting Fingerprints
• Visible prints are not a problem.
• Latent (invisible) prints require several
different techniques to be seen.
• On Hard surfaces (glass, tile, painted wood),
we use powders or super glue fuming.
• On Soft surfaces (paper, cloth, cardboard), we
use different chemicals.
Ways of Detecting Fingerprints
• RUVIS = Reflected UltraViolet Imaging Systems
• Lets us see fingerprints on hard surfaces with
powders.
• Shoots UV light which reflects and shows
prints
• They can lift or photograph the print once it
has been found.
Finger Print Dusting
Developing Latent Prints
• 1) Fingerprint powders
• Fine powder that sticks to sweat and oils on
fingerprints
• Use a camel hair or fiberglass brush to give a
light dusting over fingerprint
• Usually use grey and black powders
• Use grey for dark surfaces, mirrors and glass
• Use black for light surfaces.
• We have magnetic powders in black and grey
• Used on finished leather and rough plastics
Developing Fingerprints
• Fluorescent powders can light up a print so
you can photograph it.
2) Iodine Fuming
• Iodine does Sublimation = turning from a solid
to a gas with no liquid stage.
• Put into chamber with evidence, heat crystals
and fume the object.
• This makes the print visible
• We photograph the prints.
Developing Fingerprints
Developing Fingerprints
3) Ninhydrin
• This mixes with perspiration in prints
• Turn the print bluish purple
• Used on porous surfaces
• Sprayed with an aerosol can
• Takes and hour or two for prints to appear.
4) Physical developer
• Used when the other do not work
• Used on wet, porous materials
Developing Fingerprints
• It destroys all of the proteins, so it has to be
used last.
5) Super glue fuming
• Can be used on porous and non-porous
surfaces
• Put super glue on cotton ball mixed with
sodium hydroxide
• Put in a closed cabinet with the evidence and
heat.
• Fumes stick to prints in 4-6 hours.
Super Glue Fuming
Alternate Light Source
Developing Fingerprints
• Can also be used in closed cars.
• Now we have a hand held version to use on a
site.
6) Alternate Light Source
• Areas have to have chemicals used on it
before this can be used
• Which chemical used depends on what the
material is.
• Need to be an expert to know which one to
use
Developing Fingerprints
• New chemicals for this are being created
- None of the chemicals used to find
fingerprints mess with the DNA.
- Regardless of which method you use, the
results need to be determined by a fingerprint
analysis expert.
Preserving Developed Prints
Preserving Developed Prints
• You need a permanent copy for future use
• Must take a photograph at the scene before
you make any attempt at preserving the print.
• Photo must include where it is in respect to
the other evidence.
• If it is a small object (can, bottle), you can take
the whole thing with you.
• The print should be covered with cellophane
to preserve it.
Preserving Developed Prints
• On large objects, the print has to be “lifted”
1) Dust print
2) Use a wide piece of clear tape
3) Use the tape to pull up the dust with the
print
4) Place on a background that will show up the
print.
• Most police use a ready made version of this.
Preserving Developed Prints
• The tape and cardboard at attached together
with a piece of celluloid between them
• Remove the celluloid, peel tape, stick to
powder, press back onto the cardboard.
Digital Imaging for Fingerprint
Enhancement
Digital Imaging for Fingerprint
Enhancement
• Digital imaging = a process through which a
picture is converted into a series of square,
electronic dots known as pixels.
• Put pixels together to make a digital image.
Black and white images are called grayscale
images.
• Black is 0 and white is 255.
• Pixels can be anywhere between 0 and 255
Digital Imaging for Fingerprint
Enhancement
• The intensity of the pixels can be manipulated
by a computer.
• Once the picture is in digital form we can try
several different ways to enhance the image.
• Colored surfaces make it harder to get a sharp
image.
• Have to digitally remove the colored back
ground to get a sharp image.
Digital Imaging for Fingerprint
Enhancement
• If the print is colored (iodine, Ninhydrin),
• You isolate the print color to make it stand out
• With scaling and resizing tools, we can enlarge
a part of the print for a closer look.
• The compare function lets you put two images
side by side.
• You can zoom into both images to compare
points.