Which of the following is NOT a technique for recovering 3-D footwear impressions?

• A. Photograph with a scale
• B. Dental stone casting
• C. Silicone casting
• D. Gel lifters

Answer: (D)

Capturing 3-D footwear impressions relies on preserving the depth and contour left in the scene. Photographing with a scale documents the impression in place, showing size, orientation, and relation to surrounding features. Silicone casting uses a flexible rubber material that flows into the ridges and details of the impression and can be peeled away without destroying it, providing a detailed negative or positive replica. Dental stone casting creates a rigid, durable positive model that can be stored and analyzed later, preserving the three-dimensional features for comparison.

Gel lifters, however, are not used for recovering 3-D footwear impressions because they’re designed for lifting impressions from smooth, nonporous surfaces (often fingerprints), and they don’t reliably capture or preserve impressions embedded in substrates like soil or mud. They can distort or fail to convey the true depth and morphology needed for footwear comparison, making them unsuitable for this purpose.