In forensic investigations, which of the following is an example of trace evidence?

Trace evidence refers to small, often microscopic quantities of material transferred from one location to another during a crime. Gunshot residues are a prime example of trace evidence because they are tiny particles that can be found on a person's hands or clothing after they have discharged a firearm. These residues can include bits of burnt gunpowder and other materials from the ammunition, making them critical in determining involvement in a shooting incident.

Fingerprints, while crucial in forensic science, do not fall under the category of trace evidence as they are more direct identifiers of an individual. Blood samples provide significant biological evidence but are also not classified as trace evidence because they usually consist of larger, identifiable quantities. Witness interviews are critical for gathering information about a case, yet they do not represent physical evidence and thus do not meet the criteria for trace evidence.