Textile fibers can be exchanged between individuals, between individuals and objects and between objects. When fibers are associated with a specific source, such as fabric from the victim, suspect or scene, a value is placed on that association. A fiber is transferred and detected is also dependent on the nature and duration of the contact between the suspect and the victim and/or scene and the persistence of the fibers after they have been transferred.
Fiber examinations involve a comparison of samples from known and questioned sources to determine whether they are consistent with having originated from the same source. Laboratory analysts examine various physical, chemical, and microscopic properties of fibers when performing a comparison between evidence fibers and a potential source. Conversely, individual characteristics allow the association between two or more items with each other to the exclusion of all other items. For fiber examiners, this most often occurs when pieces of fabric or cordage are physically matched.