What is impression evidence?

• A. DNA traces left by saliva.
• B. Vapor signatures from solvents.
• C. Marks from shoes, tires, or tools transferred to a surface.
• D. Trace amounts of gunpowder.

Answer: (C)

Impression evidence consists of marks left on a surface when an object makes contact and transfers its shape. Common sources are shoes, tires, and tools, whose patterns and ridges can imprint onto floors, pavement, or other materials. The imprint preserves details of the original object, including tread patterns and wear, which can help link a suspect, item, or vehicle to a scene. Investigators document these impressions with photos, measurements, and often casts or lifts to preserve the shape for analysis. This type of evidence is about physical imprints rather than chemical or genetic traces. For contrast, DNA traces come from biological material like saliva, vapor signatures come from solvents or chemicals, and gunpowder traces are residue analyses—none of which are impressions left by contact.