Digital & Multimedia Evidence (DME) - The analysis of evidence stored or transmitted in binary form.
Computer forensics involves the recovery or extraction of data from computers and digital storage media and applies its investigation for use in court. It is used to investigate a wide variety of crime, such as child pornography, fraud, cyber-stalking, murder and sexual assault.
Examples of some of the commonly submitted types of digital evidence include: computer towers and laptops, iPad, iPod, PDAs, cellular telephones and smart phones, peripheral devices such as USB drives (or thumb drives), camera cards and Global Positioning Systems or GPS devices. This examination is performed in the Questioned Document Section.
ATTENTION – When digital evidence is collected at a crime scene, the officers or laboratory personnel collecting the evidence should have a general understanding of the possibilities of alteration or destruction. For information regarding the collection/handling of evidence, and other considerations in this discipline, please refer to the Laboratory Customer Handbook (excerpt from Crime Laboratory Service Manual) (PDF) for specific instructions.
All submissions for Digital/Multimedia examination MUST be accompanied by the proper documentation BEFORE any examination can begin. A proper Search Warrant (which authorizes not only the seizure of, but also the forensic examination of submitted digital evidence) or Consent to Search form must be submitted along with the evidence.
CASE ACCEPTANCE POLICY – In an effort to provide more efficient and effective service for Digital/Multimedia testing requests, the DPS Crime Laboratory Service has implemented the following case acceptance policies:
Video / Audio Analysis
Data recovered from either analog or digital multimedia format including, but not limited to, analog media, law enforcement in-car cameras, surveillance cameras, and/or magnetic and optical media can be further enhanced to provide information and/or clarification of image, audio or video to isolate regions of interest from the media. At the current time, the laboratory does not perform audio/video comparisons or authentications (visual identifications or voice matches) Audio enhancement can be performed to attempt to remove undesirable noise from a particular frequency, such as an electronic hum or a wind noise. We do not have the capability to remove ambient sounds involving multiple frequencies.
Forensic photographers use photography and videography to aid in documentation and reconstruction of crime scenes with specialized techniques. An example of forensic photography performed by the section is luminol blood visualization which allows crime scene investigators to see latent blood traces that are invisible to the naked eye. This technique is very sensitive and requires explicit photographic protocol to produce satisfactory results. The photographers also provide technical support to Crime Lab personnel with detailed evidence exemplars, presentations, and photographic documentation of crime scenes, including aerial views.
The section may also perform Image Enhancement which involves the application of digital techniques to isolate, clarify, or enlarge areas of interest for further examination or presentation in court.