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Back to Archives | Back to June 2009 Contents 

Technology Talk

Digital Asset Management: What Chiefs Should Know about Digital Media Evidence

By D. Miles Brissette, Assistant Criminal District Attorney, Tarrant County District Attorney’s Office, Fort Worth, Texas

ong before a jury foreman announces a case’s verdict in open court, the fate of the case’s digital multimedia evidence (DME) has been set by the digital asset management (DAM) policies of the law enforcement agencies involved in the prosecution. This column offers a cautionary tale of issues to consider when drafting or reviewing a law enforcement agency’s DAM policies.

Working a criminal episode backward from the courtroom enables those responsible for DAM in their agencies to review the needs of the modern jury. The “CSI effect”—the public’s high expectations and perceptions of an investigation’s results derived from portrayals of this process in such popular media as film and television—is alive and well every day in the courts throughout the United States. Juries today expect the prosecution to be able to take them to the scene of the criminal episode via the electronic evidence collected by the law enforcement agency. The jury room is the ultimate proving ground for DME.

Types of DME

The DME collected and maintained by an agency in response to a criminal episode can be broken down into two types: evidence generated by the agency and evidence collected by it. Agency-generated DME can include crime scene photographs, recordings or transcripts of 9-1-1 calls, recorded radio traffic, in-car video footage, intoxilizer/interview room video footage, computer-aided dispatch (CAD) reports, offense reports, statements, and photo lineups. Agency-collected DME can include video footage from closed-circuit television (CCTV), camcorders, and cellular telephones; cell phone records; and Global Positioning System (GPS)/cell tower data.

Agency-generated evidence is the core focus of an agency’s DAM policy. Agencies should focus their energy on this type of evidence to establish a comprehensive set of policies for the life cycle of a criminal episode, which begins with the call for service from the public and concludes when defendants have exhausted all of their appellate rights. For some agencies, this total DAM life-cycle approach can be a drastic shift. Advances in science and technology are moving agencies further and further from the notion that their involvement in a case is over when the prosecutor’s office accepts the case for prosecution.

Recommendations for Agency-Generated Evidence

The primary areas of an agency’s generated DME collection should include calls for service, radio traffic, crime scene photographs, and digital video footage.

The 9-1-1 call center, if properly staffed and trained to ask questions, can not only provide first responders with timely information as they arrive on the scene but can also build a list of witnesses with phone numbers with whom detectives can follow up later in the investigation.

Recordings of agency radio traffic can prove vital during critical-incident investigations, where the timing of what was transmitted or what was said when should be preserved in its original format. Today’s modern CAD systems can export an audio file in minutes. Voices contained on this audio file are only half the story; agencies must preserve the metadata-rich original storage source to replay in real time the events that took place during a critical incident. Any DAM policy must provide clear guidance to the communication division of an agency that the original data source for a critical incident must be preserved until such time that all parties to the prosecution can review audio and metadata in context.

Historically, the rationing of 35mm film by agencies was a way to preserve costs when processing a crime scene, resulting in focused crime scene documentation. Today it is not uncommon for an average convenience store armed robbery gone bad to have several hundred photographs. These photographs must be handled and stored in such a way as to guarantee their authenticity in court and should be preserved in the original format as removed from the camera.

Unfortunately, the naming structure of today’s digital cameras does not function well for crime scene processing. Many crime scene units have set up their cameras to restart their file naming convention each time the storage media are removed from the cameras. However, this setup greatly increases the level of difficulty for those working on a case during other stages of the episode’s life cycle. In a critical incident where a police officer is severely injured, it is now the norm to take several thousand photos. If the auto reset naming convention is chosen, there can be several dozen files with the same name format. In a traditional file structure, two files are not able to maintain the same name in the same folder, which causes numerous issues and confusion during the discovery process with the defense. To address this issue, an agency’s DAM policy should have any agency camera set to name files from one to infinity. The policy should state that all photos, regardless of the exposure, should be preserved. Any missing photographs will no doubt be pointed out by the defense during the cross-examination of the crime scene officer.

Whether in the patrol car making the stop or in the interview room recording the confession, digital video footage must be able to reproduce accurately the information it captures. The IACP has developed minimum performance specifications for digital in-car video systems and has conducted several regional training sessions to inform and educate law enforcement executives regarding this issue.1 It is highly recommended that agency personnel involved in the acquisition of digital video camera systems work closely with their prosecutor’s offices to determine the system’s playback capabilities for those who will be using it to prosecute criminal episodes. The lack of interoperability and proprietary formats between systems can contribute to the difficulty of prosecuting cases. Presidential Executive Order 13,388 of October 25, 2005, provides the foundation on which agencies can insist that system vendors provide a product that meets the functional needs of end users.2

A significant amount of time is spent in the forensic laboratory retracing the first responder’s steps at the collection scene. Any DAM policy should emphasize that the retrieval of DME is only one part of the evidence collection process. In most cases, to process properly the images contained in the digital recording, the proprietary codec associated with the machine that made the recording needs to be located. Recording the make, model, and serial number of the system, along with taking a quick photo of the system, can greatly speed up evidence processing in the forensic laboratory.

With the proliferation of cell phones, prosecutors and law enforcement agencies have found themselves faced with the decision of whether to order cell phone records related to a criminal episode. This decision must be made based on the inherent associated costs, either for the initial bill for the records from the cell phone provider or in terms of manpower and material storage costs during the life cycle of the criminal episode. The agency and the local prosecutor’s office must think carefully about how these records will be ordered and maintained. By having a well-structured DAM policy, an agency can plan for costs related to the collection of certain types of records maintained by cell phone providers and can address DME storage costs.

Additional Resources

For any agency planning to implement a DAM policy for collected video, the Tarrant County, Texas, Criminal District Attorney’s Office hosts one of four IACP regional forensic video laboratories and receives calls every day concerning the proper collection, storage, and processing of different CCTV images from a multitude of law enforcement agencies, both locally and from across the United States.3 The Law Enforcement and Emergency Services Video Association (LEVA; along with the Scientific Working Group on Digital Evidence (SWGDE; are two additional resources.

Due to the increase in DME that law enforcement agencies are capturing on a daily basis, it is imperative that these agencies fully understand the implications involved with not only how to obtain digital data but also how to manage and store it. DAM strategies and solutions in the form of standardized policies and procedures will substantially affect local, state, tribal, and federal law enforcement agency policy and practice. Now is the time to provide this guidance. ■


1IACP, In-Car Video Camera Systems Performance Specifications: Digital Video Systems Module, Digital Video Systems Minimum Performance Specifications Document, version 14, November 21, 2008, (accessed April 30, 2009).
2Executive Order no. 13,388, “Further Strengthening the Sharing of Terrorism Information to Protect Americans,” October 25, 2005, Federal Register 70, no. 207 (October 2005): 62023–62025, (accessed April 30, 2009).
3The other three laboratories are located at the Arizona Department of Public Safety, Phoenix, Arizona; the Cincinnati, Ohio, Police Department; and the Bristol County, Massachusetts, District Attorney’s Office, respectively. The Raynham, Massachusetts, Police Department serves as the custodial agency for the last laboratory.


From The Police Chief, vol. LXXVI, no. 6, June 2009. Copyright held by the International Association of Chiefs of Police, 515 North Washington Street, Alexandria, VA 22314 USA.

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