What is toolmark evidence?

Toolmark evidence refers specifically to the marks left on a surface when a harder object, or tool, comes into contact with a softer material. This concept is rooted in the principle that different tools can create unique impressions or scratches on surfaces based on their shape, pattern, and the force applied.

When a tool makes contact with a softer material, it can leave distinct characteristics that can later be used to match the tool to the mark it left. This type of evidence is often critical in forensic investigations, as it can help connect a suspect to a crime scene or a specific piece of evidence. For instance, firearms may leave toolmarks on bullets or shell casings due to the interaction between the firearm's barrel and the projectile.

The other options do not accurately describe toolmark evidence: residue from chemical interactions pertains to different forms of forensic chemistry, ballistic testing is focused on the behavior of projectiles and their trajectories rather than marks left by tools, and imprints made in fluid substances involve substances that don't relate specifically to the hard/soft interaction central to toolmark evidence.