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StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2024 Jan-.
Ashish Badiye ; Neeti Kapoor ; Ritesh G. Menezes .
Last Update: February 13, 2023 .
The chain of custody is the most critical process of evidence documentation. It is a must to assure the court of law that the evidence is authentic, i.e., it is the same evidence seized at the crime scene. It was, at all times, in the custody of a person designated to handle it and for which it was never unaccounted. Although it is a lengthy process, it is required for evidence to be relevant in the court. The continuity of possession of evidence or custody of evidence and its movement and location from the point of discovery and recovery (at the scene of a crime or from a person), to its transport to the laboratory for examination and until the time it is allowed and admitted in the court, is known as the chain of custody or chain of evidence.
Importance of the Chain of Custody
The chain of custody proves the integrity of a piece of evidence.[1] A paper trail is maintained so that the persons who had charge of the evidence at any given time can be known quickly and summoned to testify during the trial if required.
A record of the chain of evidence must be maintained and established in the court whenever presenting evidence as an exhibit.[2] Otherwise, the evidence may be inadmissible in the court leading to serious questions regarding its legitimacy, integrity, and the examination rendered upon it.[3] The chain of custody needs to document every transmission from the moment the evidence is collected, from one person to another, to establish that nobody else could have accessed or possessed that evidence without authorization. Although there is no limit on the number of transfers, it is crucial to keep this number as low as possible.
Evidence requires conscientious handling to avert tampering. The chain of custody is said to be the sequential documentation or trail that accounts for the sequence of custody, control, transfer, analysis, and disposition of physical or electronic evidence. The goal is to establish that the evidence is related to the alleged crime, was collected from the scene, and was in its original/unaltered condition rather than having been tampered with or "planted" deceitfully to make someone seem guilty. The chain of custody maintains the integrity of the sample. The traceability of the record of the control, transfer, and analysis of samples indicates the transparency to the procedure.[4]
Maintaining the chain of custody is critical in forensic practice.[5] This step of documentation is vital because everything done for the examination and analysis of the evidentiary sample must be authorized and recorded. The liability for the condition rests with everyone coming in contact with it. The documentation should be comprehensive with information regarding the circumstances of evidence collection, the people who handled the evidence, period of the guardianship of evidence, safekeeping conditions while handling and/or storing of the evidence, and how evidence is handed over to subsequent custodians every time a transfer occurs (along with the signs of individuals involved at the respective stage). It prevents police officers and other labs/law officials involved from tainting the evidence or misplacing the piece of evidence as it would eventually be traceable back to them, and they would be held responsible for the same.[6]
The Relevance of the Chain of Custody Documentation
The documentation of the chain of custody serves three primary purposes; to ask relevant questions regarding the evidence to the analytical laboratory, to maintain a record of the chain of custody, and to document that the sample/evidence was handled only by approved personnel and was not accessible for tampering before analysis.
The investigator or the person responsible for collecting evidence must complete the labels of the sample container/bags and the chain of custody forms to enable tracking of the sample. Each sample container label must receive a unique identification code and other relevant information such as location, date and time of collection, the name, and signature of the person who collected the sample, and signature of the witness(es). It is vital that the evidence is appropriately packed to avoid damage during transport and must be preferably sealed in tamper-evident/resistant bags or with tamper-evident tapes.
A separate chain of custody form must accompany different evidence bags. The chain of custody form shall at least include the following information:
