Types of Prints Fingerprints found at crime scenes or developed in the laboratory are categorized by some examiners as patent, latent, or plastic impressions (Lee and Gaennslen, 2001, p 106), although all three types are routinely associated with the term latent print. A patent print is simply a visible print. Many of these types of prints are wholly visible to the unaided eye, and only some form of imaging is needed for preservation. A good example of a patent print would be a greasy impression left on a windowpane. Patent prints can also be left in blood, paint, ink, mud, or dust. Lighting is a very important consideration in the search for this type of fingerprint; a good
There are two distinct types: eccrine glands open by a duct directly onto the skin surface; apocrine glands usually develop in association with hair follicles and open into them.Sebaceous glands secretes lubricating oil. The other sudoriferous gland present in skin is the apocrine gland. These sweat glands are associated with the coarse hair of the armpits and pubic area. They are larger than eccrine glands and secrete a thicker fluid (Anderson et al., 1998, p 1561). The gland’s duct typically empties into a hair follicle (above where a sebaceous gland duct would be) before the secretions reach the skin’s surface (Robertshaw, 1991). Because the contents of the apocrine gland often mix with sebaceous secretions prior to reaching the skin’s surface, it is difficult to obtain uncontaminated “pure” apocrine secretions for analysis.
Early practitioners used a variety of locally available ingredients to make their own dusting powders. Pigment offering contrast and definition against the background surface Some pigment powders offer enough adhesion to be used individually.
Fluffy brushes enables particles to be easily picked up or “loaded” onto the brush filaments. The low density of this powder also allows it to easily become airborne during the dusting process, making a dust mask or respirator necessary at the crime scene.
To spread it evenly
Ninhydrin (2,2-dihydroxyindane-1,3-dione amino acids are always present in perspiration in some amount (Speaks, 1970, pp 14–17). On contact with paper, these amino acids impregnate the surface of the paper, where they are retained by their high affinity for cellulose (Champod et al., 2004,). Amino acids do not migrate. These qualities have been exploited to produce clear, sharp images of fingerprints that were up to 40 years old (Champod et al., 2004, p 114).
Used on newspapers as well Alkaline reagents react with PD strongly
Orange prints are not permanent. Non destructive techniqueand used first.
Heated by a battery operated mechanism
giving substantial advantages over techniques such as Cyanoacrylate fuming plasticized polymers (such as clingfilm and plasticized vinyl) its use is limited to well-equipped and well-funded forensics labs.
(waxed paper, cardboard with wax finish, and Styrofoam)
conventional methods of fingerprint development
Hassan Abdul Qadir
Dr. Zafar Iqbal
Institute of Biochemistry &
Biotechnology, University of
“Fingerprints found at crime scenes lead to more suspects
and generate more evidence in court than all other forensic
Interpol European Expert Group on Fingerprint Identification (IEEFG) Methods for Fingerprint
Identification Part 1 (2004
• Friction ridges on hands are known for
thousands of years
• First suggested by Dr. Henry Flaud in 1880
• The use of chemical compounds for the visualization of
latent prints dates back only about 150 years
• Most commonly used technique for identification of
• Visible print by unaided eye.
• Example: A good example of a patent print
would be a greasy impression left on a window.
• Also in blood, paint, ink, mud or dust
• These are formed when the raised friction ridges are
physically pushed into the substrate, creating a mold of the
friction skin ridge Clay, soft wax, melted plastic,
heavy grease, and paint
• Good source of imaging for
• Plastic impressions are usually
photographed under oblique lighting
that enhances the contrast of the ridges
• These prints may also be preserved with silicone-type
• The word latent means hidden or
• Latent prints are undetectable until brought out with a
physical or chemical process designed to enhance latent print
• Affected by age, gender, stimuli, occupation, disease, and any
substances the subject may have touched prior to deposition.
• After deposition: surface area, surface curvature/shape,
• surface temperature, humidity, time since they were placed
• Help in understanding working of chemicals and
developing new reagents.
• A latent print residue is mixture of secretion from glands.
• 2 major glands in dermis sebaceous glands and
sudoriferous glands (eccrine and apocrine).
• The print is 99% water and rest is trace amount of amino
acids, lipids urea, lactic acid, creatinine, glucose and
• 250 ng of amino acid per fingerprint. They
remain there after water evaporates.
• Finely divided particles that physically adhere to the
aqueous and oily components in latent print residue on
• One of the oldest and most common methods of latent
print detection (1891).
• They have affinity for moisture and oily components in a
print causes adhesion
• Pigment (for visualization)
• Binder (for adhesion to latent print residue) (Menzel,
1999, p 143).
• Pigments included lampblack , antimony trisulfide, lead
iodide, lead oxide mercuric oxide ,mercuric sulfide
• Adhesive materials included starch, kaolin, rosin, and
• Available in different colors
Is done by reflected/absorbed light or fluorescence
By soft fluffy brush with fine hairs usually made of animal
skin. Stiff brushes can damage the latent residue
• Consists of charcoal and binder.
• Applied on light colored surfaces. Even
Show up on black glossy surfaces as light
• Produce dark gray image
• The powder is taken by brush and gently
roll on surface. Excess powder is dusted out.
The developed fingerprints are preserved
On transparent tape.
• Covers a large area
• Less substrate painting
• Creates mess
• Cannot work on porous surface
Consists of iron powder and pigment
A magnetic wand with soft plastic surface
is used to pickup the powder and applied
The iron filling is then rubbed on surface
to deposit the pigment to develop fingerprint.
Easy to clean
Can be used on both porous and non-porous surfaces.
Less effective on metal surfaces
• Consists of metal flakes of1-50μm
diameter and 0.5 μm thickness.
• Used on non-porous surface like glass,
metallic, highly-varnished surfaces, hard
rubber, safes, blue-steel guns or
• Applied by fine fiber glass brush
Fingerprints on car surface
• First used in 1959 for forensics.
• Ninhydrin is used on porous surfaces like paper and wall.
• It reacts with free amines of lysine residue in proteins
sloughed off in fingerprints
• Produces deep blue or purple color known as
• White solid, soluble in ethanol and acetone.
• Applied by spraying or dipping.
• Development is done in highly humid environment. Because
water is necessary for this reaction.
• Stored in dark place to avoid degradation.
• Development need long time without humidity
• Storage is difficult because it is degraded after sometime
• Based on the interaction between lipids and fatty acids of sweat residue
with colloidal silver particles, silver has affinity for them.
• Used for developing prints on wet surfaces because Organic residues
are insoluble in water so the physical developer can detect latent
• Produce dark gray or black impression
• Used on porous surfaces
• Used when ninhydrin and iodine fail to work
• 4 solutions
1. Maleic acid
2. Redox sol (ferrous nitrate)
4. Silver nitrate sol. Fingerprints on cardboard
1. Pre acidic wash in maleic acid to remove alkaline
2. Dip and agitate in working sol. made of ferrous nitrate,
citric acid, detergent, silver nitrate.
3. Place the sample under running water
• Short shelf life.
• Used to enhance bloody prints or detect them in blood
• It interacts with proteins in blood and give black
• Can be used on both porous and non-porous surfaces,
skin of corpses
• Used by mixing with methanol or water.
• Rinse the excess dye with distilled
• Principle: natural body fats and oils in sebaceous
material of a latent print temporarily absorb the iodine
vapors. This results in a change in color, from clear to a
dark brown, until the effect fades with time
• Iodine fuming is used to reveal prints on porous and
semiporous surfaces such as paper, cardboard, and
unfinished wood but not on metallic surfaces
• One of earliest methods
• Inexpensive and easy
• Non-destructive process - other techniques can be used
• Iodine crystals are placed
in the ceramic or glass
• Specimen to be
processed is placed in the
• Gently heating the
crystals causes them to
• The violet iodine vapor
adheres selectively to
turning them orange
• In the lab, iodine
fuming is done in a
• On the Crime scene,
Fuming wands or
fuming guns are used
• These are simple
tubes with a small
reservoir for iodine
• The reservoir is
heated and iodine
vapor is expelled from
other end of the tube
iodine fuming gun
• Semi-permanent by
treating them with a
starch solution, which
turns the orange stains
blue-black (persist for
weeks to months)
• Benzoflavone is another
Prints treated with
fixed with a dark blue
color. Iodine developed
prints fixed with
• Also called Super Glue Fuming
• Latent fingerprint development ability of cyanoacrylate
discovered in late 1970s.
• One of the most frequently-used latent print development
• Used on virtually all nonporous surfaces, including glass,
metal, coated papers, and all forms of plastics
• Principle: the vapors of cyanoacrylate are selectively
attracted to fingerprint residues, where it builds up as a
crystalline white deposit that can be photographed, or copied
onto tape strips.
1. Fumes of Cyanoacrylate (CA) ester monomers are
introduced to latent fingerprints and quickly bind with
initiators (amines and carboxylic groups) in the residue.
2. The monomer on the fingerprint residue reacts with another
CA monomer in the vapor phase to form a dimer on the
print. This reacts with another monomer, and another,
eventually forming a polymer.
3. The final phase is when the polymer chain reaction is
Int = Initiator of polymerization. Amines and carboxylic groups in
latent print are the primary initiators of Cyanoacrylate polymerization
• The object is placed in an
enclosed chamber containing a
small electric heater.
• A small tray made from aluminum
foil is placed on heater
• When it becomes hot, few mL of
cyanoacrylate are added and
• Fuming is continued until latent
prints develop (30s to 15 mins )
• Can be photographed directly or
treated with dyes to increase the
visibility and contrast of the prints .
• Effective on rough surfaces
• Vapors are extremely sensitive to fingerprint residue
• Developed impressions are more durable
• Adaptable to many different crime scene and laboratory
• Relatively cheap
• Liquid CA and its fumes can cause acute damage to
skin, eyes, and mucous membranes
• The accumulation of CA fumes on parts of a firearm
could have an unfavorable effect during a subsequent
• VMD is a long-established industrial technique for the
application of metal coatings to components such as
glass to form a mirror.
• 1968, French workers reported that VMD of a mixture of
zinc, antimony, and copper powder was capable of
developing latent prints on paper.
• Gold and zinc combination used nowadays
• VMD was found to give excellent results on nonporous
• Plastic bags and
• Glass and plastic
• Glossy card,
photographic paper, and
• Clean leather items
• Adhesive tapes (non-
sticky side). Typical vacuum metal
• The questioned surface is placed in a chamber from
which the air is evacuated.
• The chamber also contains small pieces of gold and zinc
that can be heated electrically to vaporize.
• Zinc cannot deposit on the oily residues present in the
fingerprint but gold can deposit on the entire surface.
• Gold absorbed into the oil containing ridges of the
fingerprint thus there will be no gold on the surface of the
• Next, Zinc is
vaporized and will
deposit on the
substance where Gold
is present on the
surface i.e. on the
background but not on
the fingerprint ridges.
• The area where zinc
is not deposited will
be the fingerprint Photograph of print
developed on Plastic bag by
• Can develop marks on substrates exposed to water and
conditions of high humidity.
• Can safely develop latent prints on firearms
• Outperforms all other techniques in developing prints on
• Effectiveness can be reduced by the presence of body
fluids and drug residues.
• Difficult to develop prints on heavily plasticized polymers.
• Requires expensive equipment and materials.
• Used as early as 1891 for developing latent prints on porous
• Useful on paper, cardboard, plastics and unvarnished, light-
Principle: The silver ions react with the chloride ions in salt
contained in the latent print residue to form silver chloride
(AgCl), an insoluble salt which turns grey-black when exposed
AgNO3 treatment effective because:
• The reaction to form the insoluble AgCl is quicker than the
ability of the aqueous carrier to dissolve away the soluble
• Insoluble AgCl gets trapped within the structure.
• Under room light, the AgCl gradually converts by photo-
reduction to elemental silver of dark grey-black
• Efficient development with 254 nm.
• Silver Nitrate solution uses
1-3% w/v aqueous solution for porous surfaces
3% w/v ethanol-based solution for water repellant
surfaces low absorbency of such surfaces make
developed fingerprints fragile
1. Spraying or immersion
of surface with silver
2. Rinsed with water after
treatment to remove
excess silver nitrate
3. The treated surface is
exposed to UV light
source which reduces
AgCl to metallic silver,
revealing the prints as
4. The developed prints
immediately and stored
in the dark
Latent fingerprints revealed by silver nitrate
• In prints older than 1 week,
resolution will decrease
because chloride ions in the
latent print residue diffuse
• Latent prints developed by
the silver nitrate method on
certain types of glossy paper
will often disappear within
• Used after all other methods
because stains of AgCl
cannot be removed without
destroying the print.
• Since sodium chloride is
not volatile, very old latent
fingerprints retain it and
can be developed by
silver nitrate so this can
work when other