Establishing a Chain of Custody for Audio and Video Evidence

At the beginning of a forensic investigation, experts establish a chain of custody for audio and video evidence. Our job is to offer an authoritative analysis of electronic evidence, introduced in the form of audio or video recordings. 


The content of our testimony is two-fold; interpretation and authentication. We interpret scientific information for the trier of fact. We authenticate the recording as reliable evidence with integrity, and we ask ourselves a series of questions.


  • Does this evidence have an established chain of custody?
  • Because we recovered the recorded evidence, are we responsible for establishing the chain of custody?
  • Is the recording an original or a copy?
  • Has the recording been tampered with?
  • Through whose hands has this recording passed before and after it was admitted into evidence?
  • Where and how has it been stored?
The answers to these questions may determine the admissibility of the electronic evidence, and ultimately, whether a defendant is found guilty or innocent. Establishing and maintaining an unbroken chain of custody is vital. Without it, the evidence, no matter its probative value, may be successfully challenged and ruled inadmissible. 

A chain of custody is defined as a process that documents the recorded evidence from creation to the time it’s presented to the court. The process should include keeping the evidence recording safe, list all persons who have handled the evidence, the date and time each person had the evidence for analysis, as well as their purpose and involvement with the recorded evidence


Digital media evidence submitted to court must be accompanied by a chain of custody. This chain of custody is almost always in written form. It exhibits who was responsible for the acquisition of the originally recorded evidence, who was responsible for keeping that evidence safe, and who was responsible for presenting that original evidence to the trier of fact. This chain of custody includes, but is not limited to:


  1. Information on the original recording device, including make and model.
  2. Information on how the evidence was extracted from the recorded that created it.
  3. Digital handling information from all parties that had access to the evidence between the time of its extraction and the investigation.

US Dept of Justice, Forensic Examination of Digital Evidence: A Guide for Law Enforcement 

Preservation of Recordings: The National Institute of Standards and Technology (NIST), Scientific Working Group on Digital Evidence (SWGDE) and Technical Working Group for the Examination of Digital Evidence (TWGEDE) guidelines describe: 


  • “Actions taken to secure and collect digital evidence should not affect the integrity of that evidence”.  
  • “Persons conducting an examination of digital evidence should be trained for that Purpose”.  
  • “Activity relating to the seizure, examination, storage, or transfer of digital evidence should be documented, preserved, and available for review”.  

When recovering evidence in the field or lab, we create a video recording of our process. This helps answer any questions of our process post-recovery. Plus, the video recording of our retrieval process effectively establishes a chain of custody.  


However, there are many instances when we obtain evidence from lawyers who, in turn, receive recordings from the police. If I do not retrieve the evidence personally, I must carefully read the reports, depositions, and related documents that accompany the recorded evidence. This paper trail must support the construction of a timeline; an unbroken, chronological listing that accounts for the seizure, custody, transfer, storage, and condition of the evidence.  


The timeline must be free of any gaps or periods of time during which the exact custody and location of the evidence cannot be accounted for. A weak link in the chain of custody can easily overturn a conviction on appeal. 

With the proliferation of desktop audio and video editing, recordings are frequently tampered with before they are collected as evidence. We have received recordings that have been altered and often find signs of tampering immediately.  

Online services that track the chain of custody for electronic evidence are slowly gaining acceptance with law enforcement, security companies, and the legal community. Particularly useful for the archiving and storage of video from body-cams, police dash-cams, and surveillance cameras (i.e. Ring and Nest), these services hope to modernize the handling of electronic evidence by eliminating the repeated transference of physical evidence, maintaining standardized security procedures, and providing easy access to the content of electronic recordings.

Contact An Expert

With nearly four decades of experience, you can trust Primeau Forensics to handle your investigative needs. We’ll help you establish a chain of custody and support you during trial. Contact us to learn more about our forensic services.

Primeau Forensics