Product Review: Footwear Identification with SoleMate
Written by Chris Bily   

DATABASES HAVE BECOME an important foundation of forensic science and law enforcement. Everything from DNA and fingerprints to glass and paint has a database that can be accessed and searched. Some databases provide information that allow for the identification to a particular source (such as DNA and fingerprints) while other databases provide information as to a class of materials or objects (such as glass and paint). In their infancy, these databases were slow, cumbersome, and time consuming to use, but as technology has made quantum leaps forward, these limiting factors have been mitigated to a large degree.

Among these various databases exists a storehouse of footwear information. One of the largest and most widely used programs is SoleMate, which is provided and maintained by Foster and Freeman. It consists of nearly 40,000 reference records. Each record contains an exemplar of the outsole, a photograph of the outsole, and composite photographs of four views of the uppers. In addition, each record also contains text information in the form of brand, model name, availability, and category (i.e., type of footwear).

When footwear impression evidence is discovered at a crime scene, the first determination that is sought is the manufacturer and model of footwear responsible for depositing the questioned impression. Sometimes this issue is resolved quickly when a suspect is developed, and their footwear is seized as evidence. A comparison of class characteristics can be used to either exclude the known footwear or included it for further evaluation. Other times no suspect is immediately identified, and the known footwear remains elusive. In instances such as these, SoleMate becomes an invaluable tool for identifying the manufacturer and model of footwear responsible for depositing a questioned impression—and in doing so, providing investigative leads.

History

Prior to the advent of modern technology, determining the manufacturer and model of a shoe responsible for a questioned impression at a crime scene was a daunting task. It required examiners to manually search through printed trade publications or visit footwear stores or manufacturers with crime scene photographs in hand. This was tedious, time consuming, and inefficient.

As technology advanced and computers became more prevalent in society, law enforcement agencies seized upon this evolution to develop footwear databases. While these databases were a good idea in theory, in practice they had several short comings. First, they were typically small and were inaccessible by other law enforcement agencies. Second, the quality of the images were generally poor and incomplete. Third, records didn’t contain information with regard to model availability.

How It Works

After footwear impression evidence has been photographed, the image can be used to conduct a SoleMate search. It should be noted that the photographic requirements to conduct a search are much less stringent than those that are needed to conduct a comparison. Figure 1 was taken with a cellular phone. It is low-quality, it was taken at an angle under poor lighting conditions, and it doesn’t contain a scale. While this image would be of limited value for comparative purposes, it is a suitable candidate for searching.


Figure 1—This image, taken with a cell phone under poor lighting conditions, would be of limited value for comparative purposes, but it is a suitable candidate for searching a footwear database.

When SoleMate is opened, the home screen appears, the operator clicks the Search button in the upper left corner, which opens a smaller window. In the upper left corner of the smaller window is an Add button. When the Add button is clicked, a drop-down menu of 11 buttons is displayed (Figure 2). While each of these buttons has utility, the three that are used the most for searching purposes are Shape, Logo, and Text.


Figure 2—In the SoleMate application, a drop-down menu offers a choice of 11 search types.

All SoleMate records are coded with shapes, logos, and text describing what can be seen in a reference print. There are approximately 2,500 brand logos (Figure 3) for the operator to choose from and ten classifications of shapes (Figure 4). The shape classifications consist of Round, Bar, Polygon, Regular, Irregular, Zigzags and Waves, Network, Structure, Edge, and General. Shapes and logos can be assigned to a specific part of the outsole based upon what can be seen in the crime scene impression image. Text can also be entered by clicking on the Text button and typing in numbers, letters, and symbols. The coding process is essentially a filtering process. The more information that can be coded, the shorter the the list of potential footwear. It also increases the likelihood of a correct match.


Figure 3—SoleMate contains a large library of footwear logos.


Figure 4—The SoleMate software offers ten shape classifications to help with shoe identification.

For the remainder of this section of the article, Figure 1 will be used to illustrate the coding process. One of the most notable features is the Nike Swoosh in the heel area of the crime scene impression image. The operator clicks on Logo and a window containing all logos in the database appears. Since the logo in the questioned impression is clearly Nike’s trademark logo, the term “Nike” can be entered in the Filter Logos text box in the upper left-hand corner of the Logos window. This will significantly narrow down the number of logos that need to be visually searched by the operator. Caution should be exercised when selecting the correct Swoosh logo as there are numerous versions, some with subtle differences. Adding the incorrect logo can result in a non-match even though it is present in the database.

Entering this particular Nike Swoosh logo results in a total of 1,272 records. This number can be further refined by coding for shapes present in the crime scene impression image. A series of pyramid-shaped elements can be seen in the outermost portion of the sole. A corresponding shape can be seen in Shapes under the Regular classification. Selecting this feature narrows down the total records to 46. Clicking on this bar of information allows the operator to designate where in the outsole this feature appears (Figure 5). In this example, it appears in the sole. This further refines the number of records to 26. Another prominent feature in the crime scene impression image is a curving element that runs from the toe to the instep. A corresponding shape is found under the Structure classification. Coding for this feature and designating its location reduces the number of records to 1. A compilation of this coding and its corresponding results can be seen in Figure 6.


Figure 5—Users can select a shape, and then designate where on the outsole this feature appears.


Figure 6—Each time a new element is added to the search criteria, the total number of matches decreases significantly.

Clicking on the Display Results button opens a divided screen with the Search Results on the left and an enlarged exemplar of the record selected on the right (Figure 7). To the right of the exemplar is information, including Reference, Brand, Category, Models and Notes, Unique Features, Database Update, Text, Logos, and Shapes. The search results for the questioned impression yield a list of fourteen different models of the Nike Air Max that use the same outsole. Next to each model is the release date. Above the exemplar are several buttons. The green button on the far right, labeled Sole, is a drop-down menu that allows the operator to view images of the upper from four different angles along with images of the right and left outsole (Figure 8). The information and images generated from a search can be used to quickly compile a report which can then be easily shared with investigative personnel.


Figure 7—Clicking Display Results shows the exemplar next to the search results.

[insert images: Footwear_Figure 8a.jpg & Footwear_Figure8b.jpg]


Figure 8—SoleMate offers views of the upper from four angles, as well as images of the left and right outsole.

Limitations

While SoleMate is updated quarterly, it is not all-inclusive. With the plethora of the new footwear that regularly enters the marketplace, it is impossible to account for every manufacturer and model of footwear. However, most major brands are represented (such as Nike, Reebok, Adidas). While not every search will result in a match, the majority will.

Recommendations

First, SoleMate can be used from a desktop computer or a laptop. Having it on a laptop is more advantageous in that it can be transported to crime scenes if the need arises. Having it on a laptop also allows it to be more easily shared between multiple operators if more than one person will be using it. When an operator is first trained, they should spend time going through records and becoming familiar with how shapes are coded for different manufacturers and models. Finally, there is no substitute for practice. Operators should spend time coding and searching impressions of known origin and unknown origin. Taking pictures with a cell phone of footwear impressions out in the community is an excellent source of unknown impressions.

Closing Remarks

Footwear databases are powerful tools that can provide valuable investigative leads in cases involving questioned footwear impressions of an unknown origin. The programs are relatively inexpensive and the training needed to become proficient in their use is minimal. This is unquestionably a tool to which anybody who works with footwear evidence should have access.


About the Author

Chris Bily is the Instructional Coordinator for the Next Generation Forensic Science Initiative at West Virginia University.

This article appeared in the Summer 2019 issue of Evidence Technology Magazine.
Click here to read the full issue.

 
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