A generic term used to describe physical material/ evidence discovered at crime scenes that may be compared with samples from persons, tools, and physical locations. Comparison samples may be from either an unknown/questioned or a known source. Samples whose source is unknown/questioned are of three basic types:
- Recovered crime scene samples whose source is in question (e.g., evidence left by suspects, victims).
- Questioned evidence that may have been transferred to an offender during the commission of the crime and taken away by him or her. Such questioned evidence can be compared with evidence of a known source and can thereby be associated/linked to a person/ vehicle/tool of a crime.
- Evidence of an unknown/questioned source recovered from several crime scenes may also be used to associate multiple offenses that were committed by the same person and/or with the same tool or weapon. Samples whose source is known are of three basic types: standard/reference sample, control/blank sample, elimination sample.
(Crime Scene Investigation: Guides for Law Enforcement, 2013)
