What types of substances are typically identified as trace evidence in criminal investigations?

Trace evidence in criminal investigations refers to small quantities of material that can link a suspect to a crime scene or a victim. The identification of trace evidence often involves substances that are not easily seen and may be transferred from one location to another during the commission of a crime.

Stains that appear to be blood or other bodily fluids can be classified as trace evidence because they can provide significant information regarding a crime, such as establishing the presence of a victim or suspect at a scene. The presence and analysis of blood or bodily fluids can also indicate the nature of the crime, such as whether it was violent. This evidence typically requires careful handling and analysis to identify and match to specific individuals, reinforcing its role as trace evidence.

Other options, while relevant to criminal investigations, do not fit the classification of trace evidence as directly as bodily fluids. For example, skid marks, while they can indicate vehicle involvement in a crime, are not as subtle or small-scale as trace evidence. Drugs and chemicals generally represent larger quantities of substances involved in criminal activities but serve a different purpose in investigations. Witness statements, though critical for establishing narratives and timelines, fall outside the physical evidence category used to connect individuals to a crime scene.