Forensic evidence

FOOTPRINTS : AS A FORENSIC
TEJASVI BHATIA

 Introduction
 Nature of footprints
 Scope of footwear impressions
 Its types
 Gait pattern
 Collection and preservation
 Preservation of prints by photography
 Casting of an impressions
 Electrostatic lifting of dust prints
 Examination procedure of impressions
 Its forensic significance
 References
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 "Wherever he steps, whatever he touches, whatever
he leaves, even unconsciously, will serve as silent
witness against him. Not only his fingerprints or his
footprints, but his hair, the tool mark he leaves, the
paint he scratches, the blood he deposits or collects.
All of these and more bear mute witness against him.
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 Footprints are a common type of impression
evidence found at or near the crime scenes.
 Shoeprints are the specific term for prints made by
shoes. They may either be indentations in the ground
or something placed on to the surface that was stuck
to the bottom of the foot.
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 A Footprint may be a foot impression or a footprint
(dust print).
 Foot impression is described as three dimensional
impression which occurs when the foot trends in
some moldable material such as earth, sand , clay,
snow,and so on.
 Footprints: are formed on hard base when the foot or
the sole and heal of a shoe are contaminated with
some foreign matters such as road dirt , dust , flour ,
blood,moisture etc. They may also be latent.
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 The foot of a human or animal is unique in its
structure and is readily distinguishable.
 The shapes of foot impressions also differ from
individual to individual.
 Footwear and tyre evidences are also important
because of the individuality imparted to them due
to number of factors including infinite wear and
tear patterns.
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 Different shoes will leave behind prints of different
sizes and patterns.
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 Most suspects wear shoes.
 Footprints are always left, it is whether they can be
located and differentiated from other prints.
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1. Three dimensional impression
 Shoeprint made in soft material (dirt, snow)
 Requires making a cast of the print.
 Composition of dirt or
Snow will determine the
detail of the impression.
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2. Two dimensional print (visible)
 Dirt or other material picked up by shoe and
deposited onto flat, hard surface
 Variety of surfaces and
materials deposited
makes recovery of
these prints complex.
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3. Two dimensional print (latent)
 Can leave behind barely visible dust
 Can leave impression in polish/wax/dust
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3. Two dimensional print (latent)
 Can leave behind barely visible dust
 Can leave impression in polish/wax/dust
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 Link suspect or victim to scenes
 Link two crime scenes
Location of prints can:
 Lead to more evidence.
 Gait or Tracking information?
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 A Gait pattern is identified from the direction line ,
the walk line, the foot line ,the foot angle ,the step
angle ,the step length, the width of step of the foot or
footwear.
 Individual marks give indication only rarely,
whereas it is possible to determine the same from the
gait pattern as it varies from man to man according to
his height and habits.
 There are drag or slippage marks if he is walking or
running.
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 Class Characteristics can be used to eliminate a
suspected shoe or suggest a shoe could have made
the impression.
 Size
 Pattern
 Suspect shoe or test impressions compared
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 Individual Characteristics can be used to
identify an exact shoe.
 However, these can change over time.
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 Sequence and manner.
 Links between crime scenes
 The type, size and areas of specific wear on the
shoes.
 Certain seasons or weather conditions lend
themselves to the creation of footprint impressions
than others. Soil trapped in soles can also give useful
leads.
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 The lack of training and education.
 Not believing that the impressions can be found at
the scene after people have walked over the scene.
 Incomplete searches of the crime scene;
 Weather conditions;
 The impression has been intentionally destroyed.
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 Due to numerous nuances, all shoeprints
should be recovered from the scene.
 Scene should be controlled to prevent destruction
of evidence.
 Footprints are present outdoor as well as indoor.
 Some indoor prints can be visualized by darkening
a room and using a bright light at a low angle.
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 Footprints should be documented: Location
recorded and photographed.
 Objects with footprints should be removed if
possible (paper, glass).
 If can’t be removed , an examination quality
photo should be taken.
Ruler : allows for enlargement to real size.
 Preservation of the footprints should be
accomplished by both photographing and casting
and lifting in case of dust prints.
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 The camera is placed vertically above the impression
on a tripod with a scale placed next to the impression
.
 The film plain should be parallel to the impression.
 Two scales should be used in the photograph at right
angles.
 Both black and white and color photographs should
be taken of the prints.
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 A glass sheet should be held over the impressions as
close as possible but without touching the
impressions.
 Then the contours of impression are sketched on the
glass plate with maximum possible detail.
 The glass plate can be transferred to the laboratory.
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 Cast picks up detail; is durable
 Cast after photo
 Use dental stone, or plaster of Paris
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 Three dimensional impressions should always be cast
if there is clarity and the surface will permit.
 Different materials can be used for casting of
footprints: Plaster of Paris , sulfur casting, dental
stone, plastic powders , modeling clay etc.
 Impression prints , such as shoe prints in soft earth,
wet sand etc. or a similar material that can record the
shape and dimensions of the object can be preserved
by casting.
 Casting is done with plaster of Paris mixed with
water.
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 Then, the frame is put over the footprint and
saturated soln. of P.O.P is poured carefully into the
print.
 Wire mesh is kept and again the soln. is poured .
 After it gets solidify , soil particles adhered are
removed with a soft brush.
 Before the cast hardens,
it should be marked by a
sharp instrument.
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 Impression is prepared first by spraying a thin layer
of “ Snow Print Wax” and allow it to set for ten
minutes .
 Talcum powder or gray primer spray can be used .
 Prepare a mix. of dental stone using very cold water.
 Pour the dental stone onto the impression carefully.
 Cover the impression with a box and allow the cast to
dry for about 60 mins.
 Remove and air dry the cast.
 Dental stone donot require the use of fixatives such
as spray lacyuers which are done when plaster of
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 Sulfur casting is another procedure used for snow
prints.
 In this,the sulfur is melted in a 1-quart aluminium pot
and poured into the print.
 As it comes in contact with snow,it solidifies soon.
 But it is very fragile ,hence care must be taken while
handling.
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 The impressions can be lifted using photographic
paper/film or transparent adhesive tape, electrostatic
lifting, by carbon paper ,silicone ,etc.
 The fixed photographic film/paper is moistened to
make the emulsion side slightly sticky.
 A uniform gentle pressure is applied without any
slippage or sliding of the film/paper .
 It is then lifted carefully and dried. The impression
transferred into the film can be used as a negative to
make copies.
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 For a dusty or a light colored print, black photo
bromide paper is utilized.
 And for a blood stained or black print , white photo
bromide paper is used.
 The processed paper so obtained is moistened with
water preferably mixed with a few drops of ammonia
and kept for a few minutes.
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 A black vinyl sheet is placed over the suspected area
containing the impressions and is covered with
aluminium foil through which a high voltage (1500
volts) is applied.
 The dust particles ,which form the impressions, are
attracted towards the vinyl sheet.
 This can be photographed.
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Electrostatic Lifting:
 A charge is used to lift dry materials from surface to
black film.
 Lift provides more contrast
 Non-destructive
 Photographed for evidence
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 It is well established that every mark has an
individuality which cannot be duplicated even with
the best of human skill and scientific technique. The
individuality in a given mark can be established from
the below factors:
1) Dimensions 2) Shapes
3) Patterns
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 These are frequently found in the investigation of
crime . They sometimes provide positive evidence.
These are identified by the study of following
characteristics:-
 Margins Crease marks
 Toe marks Phalange marks
 Toe or ball line Pits , Cracks &Cut marks
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 If footwear is recovered from the scene of crime, it is
possible to identify the footwear from the various
characteristics of the footwear like; material used, its
wear and tear, etc. The size and the condition of the
footwear can also reveal the height, health of the
person, etc.
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 Physical measurements & examination of class and
individual characteristics leads to the examination of
footwear impressions & these are:-
 Dimensions
 Repair marks
 Wear and tear
 Foreign material / inclusions
 Any other characteristic
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 It is very common in impression evidence in almost
all the cases: although it is a tedious work to examine
footprints.
 Due to the normal walking habit of an individual ,
there is variation at different positions in the foot.
 The length of the step.
 Signs of wear n tear,marks of fittings that have come
off,injuries,marks of nails & repair marks
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 The size and shape of the shoe or a pattern in the heel
or sole is of lesser evidential value .
 Helps to determine the point of entrance and point of
exit.
 Gait pattern may indicate that the subject had
sustained an injury or walked with a limp.
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 BARRY A.J.FISHER;Techniques of Crime
scene Investigation (1993); Page (244-253)
 P.L.KIRK; Crime Scene Investigation;
Page(74-80)
 William J. Bodziak ; Footwear Impression
Evidence, Elsevier Series, 1990
 Dr. B.R.Sharma; Forensic Science In Criminal
InvestigationAndTrials, Page(175-215)
 www.crime-scene-investigator.net
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