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
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.
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
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.
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.
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 Manufacturers 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.