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Collecting DNA Evidence at Property Crime Scenes

Chain of Custody

Chain of Custody

Photo of DNA strand
National Institute of Justice (NIJ) (see reuse policy).

The chain of custody is a tracking record beginning with detailed scene notes that describe where the evidence was received or collected. Collection techniques, preservation, packaging, transportation, storage and creation of the inventory list are all part of the process used in establishing the chain of custody. The chain of custody is established whenever an investigator takes custody of evidence at a crime scene. The chain is maintained when evidence is received from another officer or detective.

A clear, well-documented chain of custody should be established through a process that includes the following:

  • Taking notes, including documentation of the recovery location, the time and date recovered or received, description of the item, condition of the item and any unusual markings on or alterations to the item.
  • Marking and packaging the evidence.
  • Sealing the evidence.
  • Preparing the chain-of-custody record.

The chain-of-custody record for all items collected from the scene must include the following:

  • Unique identifier.
  • Item description.
  • Identity of the person who collected the item.
  • Time and date of collection.
  • Location where item was found.

Individuals assuming custody of the evidence from collection through analysis sign a chain-of-custody document or otherwise conduct a secure electronic transfer identifying them as contributors to the analysis of the evidentiary materials. When evidence is submitted to a property and evidence section or to a forensic laboratory, a receipt documenting the transfer is obtained. 

To maintain an accurate and complete chain of custody:

  • Limit the number of individuals handling evidence.
  • Confirm that all names, identification numbers, and dates are listed on the chain-of-custody documents.
  • Ensure that all evidence packaging is properly sealed and marked prior to submission.
  • Obtain signed or otherwise secure receipts upon transfer of evidence.

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