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Necessary Precautions for the Preservation of Evidence

NCJ Number
Detective Volume: 6 Issue: 1 Dated: (Spring 1976) Pages: 14-17
W C Boden
Date Published
4 pages
These guidelines cover the nature of physical evidence and precautions necessary for the preservation of such evidence.
Physical evidence is any object associated with a crime and which tends to prove or disprove a point regarding the crime, victim, or perpetrator. The chain of custody is an unbroken chronicle of proof relating to the possession and analysis of the evidence until its appearance in court. Evidence may be fixed or movable. The first step in the chain of events related to physical evidence is the crime scene search, while laboratory analysis is the second significant step. The investigator should place primary emphasis on protection of the crime scene and secondary emphasis on collection of evidence. Photography and sketches are the best way of protecting the crime scene. The five steps recommended by the Federal Bureau of Investigation for collecting and preserving evidence are (1) obtaining it legally; (2) describing the evidence in detailed notes; (3) identifying it accurately and positively; (4) packaging it properly for identification, storage, or shipment to the laboratory; and (5) establishing and maintaining the chain of custody. Specific precautions should be taken in handling weapons used in an attack, clothing, firearms, blood stains, seminal stains, fingernail scrapings, hairs, fibers, drugs, and poisons. The investigator's equipment should include fingerprint accessories, a vacuum sweeper with special filters, containers, tools, magnifiers, casting equipment, and ultraviolet light equipment. The success of the laboratory technician's analysis depends directly on the investigator for the quality of the physical evidence. Photographs and 13 reference notes are provided.