Crime

Scene

Photography

FOOTWEAR AND TIRE IMPRESSION EVIDENCE

FOOTWEAR AND TIRE IMPRESSION EVIDENCE

By

Professor Bob Warnock

and Jerry Dambrogio

FOOTWEAR EVIDENCE

DIRECT PHYSICAL CONTACT TRANSFER OF CLASS AND OR

INDIVIDUAL CHARACTERISTICS

IMPRESSION EVIDENCE

“objects or materials that have retained the characteristics of other objects or materials through physical contact”

Persons committing a crime leave footwear impressions en route to, at and exiting from the crime scene.

THREE-DEMENSIONAL IMPRESSIONS

Are those that have significant depth, in addition to length and width.

These are normally found in: Soil Sand Snow

THREE-DEMENSIONAL IMPRESSIONS

n THREE-DEMENSIONAL IMPRESSIONS n Photograph Cast

TWO-DEMENSIONAL IMPRESSIONS Photograph Collect substrate if Possible

If not recover with appropriate technique

Three- Dimensional Impression

Photograph Document Cast

Cold Weather Casting

Partial melting of the original details due the heat generated by the setting of the casting material.

Another common problem is the freezing of the casting material before the cast has set.

Cold Weather Casting

Gray Auto Primer Snow Wax Addition of snow to the casting material

during mixing. Potassium Sulfate

TWO –DEMENSIONAL IMPRESSIONS

Positive impression An impression that results when a shoe

deposits material onto a substrate. The residue visually represents the areas

of the sole that actually came in contact with the surface.

TWO –DEMENSIONAL IMPRESSIONS

Negative impression Is produced when the contact area of the

shoe remove residue from a surface and in which the residue on the surface remains where the areas of sole did not come in contact with the surface.

Negative impressions occur less frequently then positive impressions.

TWO –DEMENSIONAL IMPRESSIONS

Dry origin residue impression. When shoes track across a dirty surface,

the bottom of the soles will accumulate a coating of residue. If they then track onto a relatively clean surface, the same residue will be deposited in the form of footwear impressions.

TWO –DEMENSIONAL IMPRESSIONS

Wet origin impression Impressions made when a clean shoe sole

is wet or damp or the receiving surface is wet or damp.

This type of impression may be enhanced with fingerprint powder.

TWO-DEMENSIONAL

Photography –Oblique Lighting Recover Substrate Lift Impression

Gel-Lift Electrostatic Lifter Carbon Paper

Electrostatic Lifter

The electrostatically charged lifting film is drawn down to the surface, and the dust particles in the impression are attracted to the lifting film.

The construction of the film allows it to store the electrostatic charge, thus retaining the dust particles after the charge has been disconnected.

Electrostatic Dust Print Lifting Devices

Used On: Paper Linoleum Seat Covers Wood Carpet Concrete Asphalt

Dust Impressions

Used on dry dust impressions only….. The film with the impression is viewed with

oblique lighting. Dust impression should be photographed

prior to attempting to lift them.

Gel-Lifting

Gel lifters contain a thick, non-aggressive, low-adhesive gelatin layer that permits the lifting of traces from almost every surface.

View under oblique lighting. Photograph impression before lifting.

COMPARISON METHODOLOGY

SIDE BY SIDE OVERLAYS COMPARISON MICROSCOPE

AREAS OF EXAMINATION

DESIGN (FULL OR PARTIAL) Manufacturing Characteristics Physical Shape and Size Wear Characteristics Individual Identifying Characteristics

Nomenclature

CLASS CHARACTETRISTIC

PHYSICAL SIZE SHAPE GENERAL DESIGN

Manufacturing Processes

Molded processes, where the soles, once molded, represent their final size and shape.

Cut processes, where soling material initially molded or formed, is then cut or trimmed in someway before reaching a final shape and size.

MOLDING PROCESSES

Compression-Molded Outsoles Injection – Molded Outsoles Open-Pour Molding

Molded Processes

Calendering Processing

Many variables occur during the calendaring operation that contribute to making the outsole material, and therefore the resulting outsoles extremely individual.

Cut Processes

PHYSICAL SIZE

NOT A SHOE SIZE BUT THE PHYSICAL DIMENSIONS OF THE SOLE AND DESIGN PATTERN.

ONE PERSON – MANY SHOESTYPE SIZE LENGTH WIDEST PART

Nike Tennis 8 ½ 279mm 90mm

Nike Tennis 8 ½ 285mm 94mm

Nike Jogging 8 ½ 290mm 111mm

Bass Sandals 10 M 282mm 90mm

Bostonian Loafers 8 ½ 295mm 109mm

Bostonian Loafers 8 ½ 285mm 98mm

Sperry Deck Shoe 8 ½ 286mm 103mm

WEAR EXAMINATION

EFFECT OF FRICTION AND ABRASIVE FORCES ON SOLES

IT IS THE POSITION AND DEGREE OF WEAR THAT IS RELEVANT

GENERAL WEAR

Same Pair 45 Days Later

Same Pair 90 Days Later

Area of Major Changes

SCHALLAMACH PATTERN

Occurs on a sole as a result of abrasive wear.

The abrasion causes the rubber to stretch and roll over.

The resultant ridges (tendrils) create ridge patterns similar to that of a fingerprint.

SCHALLAMACH PATTERN

The pattern is unique and can be used as the basis for a positive identification.

The pattern can change completely after between 6 to 16 hours of additional wear.

The pattern normally runs perpendicular to the axis of the shoe, primarily in the toe and heel area.

SCHALLAMACH PATTERN

COMBINED CLASS CHARACTERISTICS

Combined class characteristics can rapidly reduce the number of shoes sharing those characteristics, the following hypothetical but not uncommon example is offered.

1. 10,000 pairs of size ten basketball shoes out a total order of 75,000 shoes of same design and brand are made

2. In order to meet production demands four pairs of size ten molds were used. Each hand graved mold is easily distinguishable from each other. This gives you 2,500 pairs from each mold.

COMBINED CLASS CHARACTERISTICS

3. If you match up one left from a mold and one right from a mold it reduces the total possible pairs down to 625 pairs.

4. If another variable characteristic such as a toe cap which varies in its position is part of the manufacturing process and can occur in one of ten ways on each outsole , the chances of a left pair and right shoe from the same respective left and right mold and having the other identical variable would be 6.25 chances out of 10,000

RESULTS

Positive Identification Non- Identification Probably Made Possible Made Possible Did Not Make Non-Conclusive

POSITIVE IDENTIFICATION

It was determined that the impression represented by the cast was made by the right shoe submitted

NON-IDENTIFICATION

It was determined that the impression represented by the cast was not made by the right show .

PROBABLY MADE

It was determined that the questioned impression corresponds in design, physical size and shape and general condition with the known right shoe.In addition, the correspondence of two random individual characteristics indicate it is highly probably the impression was made by the right shoe. It is very unlikely that another shoe of the same design, physical size and shape , and general condition would also share the aforementioned characteristics.

POSSIBLY MADE

It was determined that the questioned impression corresponds in design, physical size and shape and general condition with the known right shoe. Due to the limited detail retained in the impression and lack of observable individual identifying characteristics, a closer association was not made between the impression and known shoe. The possibility exits that another right shoe(s) of the same specific design, physical size, and general condition, made this impression.

POSSIBLE DID NOT MAKE

Similar design features exist between portions of the questioned impression and the known right shoe; however, some possible differences exist indicating the questioned impression may not have been made by the right shoe.The limited clarity of the impression precludes a more detail examination.

NON-CONCLUSIVE

Unable to state whether the shoe did or did not make the impression.

This may be based on lack of detail in the question impression or lack of a suitable object for comparison.

Tire Impression Evidence

The dimensions of a vehicle can be used to recognize the Manufacturer’s brand and model.

Front Track Rear Track Wheelbase

Front Track Impression

For best results measure the track across parallel tracks running in a straight line.

Measure from the center rib on one track to the center rib on the other.

Rear Track Impression

Rear track can be measured in either a turn or in the straight run.

Wheelbase

Front and Rear Track

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Wheelbase