The use of electro-static dust lifting devices to obtain shoe impressions has been well documented and accepted by the forensic community. These devices operate by inducing an electrical charge to a sheet of metalized film that has been placed over the crime scene impression. The electrical charge attracts the particles of the shoe impression, transferring it to the lifting film. Electro-static lifting is generally considered an non-destructive process and is an ideal step to follow traditional photography techniques. This method works very well on surfaces which are smooth, hard, and dry, such as countertops, glass, and doors. These types of surfaces typically allow for near total contact between the film and the surface containing the impression. A rubber roller can also be used to smooth out the film over the surface.

By way of contrast, cylindrical surfaces pose several challenges to the analyst. Cylindrical, or curved, surfaces may be much more difficult to photograph than flat surfaces due to lighting and depth of field issues. Generally speaking, the greater the curvature of the object, the greater the difficulty the analyst will likely encounter during the documentation process. In addition, traditional lifting techniques may not be well suited for curved surfaces. The inability to properly secure lifting film over the impression area may lead to slippage and subsequent damage or distortion to the impression while rolling. The inability to make near total contact between the lifting film and the impression may also lead to undesirable gaps or wrinkles in the film. These difficulties are significantly increased when the curved surface is soft and flexible.

Crime scene analysts rarely encounter footwear impressions on cylindrical objects. Occasionally however, analysts may encounter impressions contained on cylindrical objects such as bottles, baseball bats, handrails, or in this case, insulated pipe foam. While the need for this lifting method may remain rare in general crime scene processing examiners should consider this method when faced with movable cylindrical or curved surfaces.

< read the complete article >

Article submitted by the authors. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

• Preservation Methods and the Degradation of Dust Print Lifts by Marcy Hendricks
• Casting Two-Dimensional Bloody Shoe Prints from Concrete, Fabric, and Human Skin: A Review of Several Methods with Recommendations, by Thomas W. Adair
• Analysis of Footwear Impression Evidence, by Sargur N. Srihari