Fingerprints

1
Fingerprints

• By Harmita, Ashley, and Peter

2
History of Fingerprints

• 1892 - Sir Francis Galton was the first to study
  finger prints
• His work led the creation of the first
  fingerprint filling system
• 1896 Sir Henry Edward created the ten print
  system of classification.

3
History of Fingerprints

• In this system patterns were given a point value
  depending what finger it was found on. This was
  done for all ten fingers and the numbers were
  then grouped together giving a fraction like code
  for that specific set of ten prints.
• Widely used until the implementation of computers
  in the 20th century
• Today Fingerprints can be scanned into a
  computer and matched across a database of known
  prints to find a match.

4
What are fingerprints?

• Impressions created by ridges on the tips of
  fingers, palm of hands, and soles of feet.
• Formed during the 3rd and 4th month of fetal
  development
• Remain the same the rest of our lives, the
  pattern gets larger as we grow, and the pattern
  is regained after the skin is damaged
• No two people in the world have exactly the same
  fingerprints.

5
Analysis of Fingerprints

• Minutiae are discontinuities of the ridges
• A suspect print is analyzed by being compared to
  a print found at a crime scene. If there are a
  certain number of points of minutiae that match,
  then a match is made

6
Different Types of Fingerprints

• Latent prints
• Hidden and deposited through the secretions of
  the skin.
• Sweat- main component, water evaporates
• Solid components and amino acids, glucose, lactic
  acid, peptides, ammonia and inorganic compounds
  like potassium, sodium etc are transferred
• Visible through several techniques
• Patent prints
• Highly visible from substances like blood
• Photographed
• Plastic prints
• Friction ridge impressions deposited in a
  material that retains the shape such as clay or
  melted wax.

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Classification of Fingerprints

• Arches
• Loops
• Whorls

8
Techniques for lifting fingerprints

• Dusting
• Different powders
• Iodine Fuming
• Chemical Treatment
• Superglue fuming

9
Dusting

• Good on non-porous materials such as wood, metal,
  or glass.
• The area is lightly and carefully dusted with
  either a black or white powder using camels hair
  brush
• The dust is lifted with clear tape for further
  analysis.
• The print is preserved via photography

10
Powders on Non-porous surfaces

• The type of powder is chosen depending on the
  contrast of the surfaces type.
• Black powder (charcoal)- white or light colored
  surfaces
• Grey powder (aluminum dust)-dark colored surfaces
• Stick to perspiration residues /body oils left on
  surfaces.

http//www.evidentcrimescene.com/cata/kits/kits.ht
ml
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Magnetic Powders/Fluorescence Powders

• Magnetic powders
• Advantage
• Avoids damage to the prints
• Fluorescence powder
• Advantage
• Florescence under UV light

http//www.ndted.org/EducationResources/CommunityC
ollege/MagParticle/Equipment/Particles.htm
http//www.vastacademy.com.au/vsp_subcat/3/60
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Iodine Fuming

• Suspect material is placed in an enclosed area
  along with iodine crystals.
• The crystals are heated, and will sublimate.
• The vapors cause the prints to appear brown in
  color.
• Immediate transfer to highly polished silver
  plate 5 sec.
• Exposure of silver plate to light source.

http//www.bxscience.edu/publications/forensics/ar
ticles/fingerprinting/r-fing01.htm
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CHEMICAL TREATMENT

• Silver nitrate is sprayed onto the porous surface
  and left to dry. Then it is exposed to
  ultraviolet light to visualize the prints.
• Reacts with the salts in perspiration develops
  prints that appear reddish-brown or black in
  color.

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Chemical Treatment cont

• White powder contains ninhydrin
  (triketohydrindene hydrate)
• The 0.6 solution of ninhydrin powder with a
  suitable solvent, like acetone or ethyl alcohol
  is sprayed onto a porous surface via an aerosol
  can.
• Chemical reaction with amino acids.
• Purple- blue prints

http//www.flickr.com/photos/11333635_at_N02/11110818
54/
15
Chemical Treatment cont.

• Cyanoacraylate Fuming
• Household items
• Gention Violet
• Stains non-living epidermal cells

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Cyanoacrylate Fuming

• Aka Superglue fuming.
• Superglue fuming is a chemical technique used to
  expose latent fingerprints.
• The basic concept is to apply something that will
  chemically react with one of the constituent
  chemicals of latent fingerprints. The resulting
  reaction will give the fingerprint a new chemical
  composition rendering it visible.
• Super glue reacts with the traces of amino acids,
  fatty acids, and proteins in the latent
  fingerprint and the moisture in the air to
  produce a visible, sticky white material that
  forms along the ridges of the fingerprint.

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Cyanoacrylate Fuming

• The surfaces that are to be checked for latent
  fingerprints are placed in an airtight tank along
  with a small heater. A few drops of liquid super
  glue are placed into a tiny, open container, and
  the container is placed on top of the heater
  inside the tank. The tank is then carefully
  sealed, and the heater activated.
• Since it is very difficult to calculate this
  amount of time in advance, the reaction must be
  monitored to insure that it is not allowed to
  continue for too long. If it runs unchecked, the
  latent fingerprints can overdevelop the chemical
  images of the ridges will slowly grow wider until
  they overlap, obscuring vital detail.

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Cyanoacrylate Fuming

• There are a few methods by which the process may
  be accelerated. These add to the complexity of
  the basic procedure, but offer vast improvements
  in the speed of the reaction.
• 1. The fume circulation method - if the super
  glue fumes are actively circulated around the
  tank, the air inside will have a constant
  concentration and all latent fingerprints in the
  tank will be in constant contact. In practice,
  the fumes can be forced to circulate by the
  strategic use of electric fans inside the tank.
• 2. The chemical acceleration method - Instead of
  being an addition to the basic procedure, the
  chemical acceleration method is a replacement for
  part of it. When the chemical acceleration method
  is used, the heater is discarded and a chemical
  like sodium hydroxide is placed in contact with
  the super glue. This chemical will cause the
  super glue to produce cyanoacrylate fumes, and
  the reaction will then proceed normally.
• 3. The water vapor method - Since the reaction
  requires moisture in the air to occur, the air in
  the tank can be kept at a high level of humidity
  to ensure that there will always be enough
  moisture for the reaction to take place. The
  humidity in the tank can be kept high simply by
  placing an open container of water inside the
  tank.

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Black Substrates

• Non-Porous
• Plastic trash bag
• Textured metal
• Linoleum
• Tile

• Porous
• Construction paper
• Leather
• Semi-glossy photographic paper

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Chemicals used for Comparison

• Tartrazine
• Acid Yellow 7
• Merbromin
• 2, 2 Azino-di (3-ethyl-benzthiazoline sulfonic
  acid (6) or A.B.T.S
• 1, 8-Diazafluoren-9-one or DFO

Metal
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Semi-glossy paper
A.B.T.S
Tartrazine
Merbromin
D.F.O
White gel lifter
Acid yellow
22
Reference

• http//pagesperso-orange.fr/fingerchip/biometrics/
  types/fingerprint.htm
• http//www.swgfast.org/Simultaneous_Examination_St
  andards_1.0_DRAFT_FOR_COMMENT.pdf
• www.crime-scene.com/ecpi/A-2614C.shtml
• www.fosterfreeman.com/.../mvc1000/mvc1000.html
• http//www.ccs.neu.edu/home/feneric/cyanoacrylate.
  html
• www.bxscience.edu/.../r-fing01.htm
• http//library.thinkquest.org/04oct/00206/lo_nts_f
  ingerprinting.htm