Digital evidence in law enforcement could refer to two different, but related, things. First, it may refer to evidence that potentially exists on a suspect's computer hard drive or other data storage device that law enforcement may want to retrieve. Second, it may refer to the way law enforcement stores various types of evidence that could be stored in other ways, such as in paper files.
A forensic analysis of a computer system may be necessary if law enforcement is searching for digital evidence. Law enforcement agencies have experts in information technology that have the skills to retrieve information that may have been deleted off a storage device. If a smaller agency does not have those specialists on staff, it may contract with a larger agency to provide those services when they are needed.
The retrieval of digital evidence from a suspect's storage device can be a very delicate process. Each piece of evidence must be carefully recorded. The digital evidence must be retrieved in such a way that there is no question about its integrity and investigators cannot be accused of contaminating the evidence. Therefore, those who are specifically trained in processing digital storage devices are important to any investigation involving such equipment.
Certain ways that law enforcement agencies store various types of evidence may also be referred to as digital evidence. For example, whereas in the past police may have taken photographs on film and had that film developed, now police may choose to take digital pictures and present them on a computer screen or with a projector. Also, whereas in the past fingerprinting has been on paper, more law enforcement agencies are now turning to digital imaging for fingerprints.
Utilizing this type of digital evidence enables police to save cost, but also adds a great deal of convenience to the process of storing and retrieving evidence. It is now easier for police to pull up certain pictures that may be used in court and print out only those that are needed, if prints are needed at all. Further, digitally archiving fingerprints enables law enforcement to conduct searches for matches in a way that was never possible in the past.
Although these are some positive benefits to digital evidence, there are also some drawbacks. Digital evidence may be changed or tainted in easier ways or ways that are more difficult to determine. Therefore, some attorneys may question whether the evidence meets certain standards and could successfully thwart efforts to introduce otherwise valid evidence. Also, data storage devices can sometimes fail, leading to a loss of evidence. Such losses can be mitigated through regular use of backup systems, though care must be taken to ensure that all copies are treated with the same level of security as the originals.