Digital data are all around us and are collected routinely in most investigations. More likely than not, someone involved in a crime operated a computer, used a mobile phone/device, or accessed the Internet. Additionally, digital audio, photography, and video recording devices are nearly everywhere; most businesses and many local and state governments have security cameras/devices that can yield a surprising amount of photos/video. To meet this growing demand, there are several specialties in Digital & Multimedia Sciences. Digital & Multimedia Sciences professionals not only perform and conduct digital forensic examinations, they also help develop the scientific foundations for the practice of digital forensics, including research and publication, and they may manage digital forensic laboratories.
Media analysis of a computer can recover deleted files
Digital evidence examinations require very specific hardware and software tools to find numerous types of digital evidence. Examiners, depending upon their specialties, may discover evidence and provide testimony concerning the following:
- Digital device examinations
- Network analysis
- Examination and comparison of digitized numerals, images, analog/digital audio and video (which includes examinations such as authenticity, photogrammetry, and enhancement)
Computer forensics used to involve simply looking at individual computers which may have some connection to criminal activity. With the ready availability of access to the Internet, intrusions to gain access to or corrupt information on other computer systems by criminals have become widespread. Network forensics is required to properly investigate and determine what happened. This extends to mobile devices with the explosion in smart phone and tablet systems that provide fully networked computing technology in the palm of your hand.
The analysis of audio recordings requires techniques and procedures which continue to be evolving areas of research. Forensic speaker comparison, acoustic analysis and enhancement, and audio authenticity examinations are all important activities which can aid investigations and assist in the settlement of disputes. With capabilities to disguise voices as well as easily manipulate digital audio with off-the-shelf technology, the investigation of underlying acoustic patterns has become one of many important areas of both technological and linguistic research.
Spectrographic analysis of an audio recording
The advent of digital photography provides the potential to aid in the documentation of crime scenes and injuries. Digital photography also provides a source of images from witnesses, victims, and subjects due to the widespread availability of digital cameras in laptops, tablets, and smart phones. An extension of the explosion of technology is the widespread availability of video recording capabilities. Nearly every mobile device can record video, providing more sources of evidence than ever before. Over 100,000 photographs and 13,000 digital videos were reviewed in the Boston Marathon Bombing investigation, which added the complexity of sheer volume to the traditional issues in digital image and video examinations. Deriving important information from digital photographs and videos relies on the ability to authenticate such images as well as enhance and conduct analysis to extract meaningful evidence.
The work in a digital and multimedia examination might address some of the following questions:
- What files have been deleted from the digital device?
- What other digital devices have been connected to this system?
- Was this system attacked or modified by someone over the network?
- Can a remote system or user be located or identified?
- What sites on the internet were visited by this system?
- Was this audio recording altered?
- Can this video recording be enhanced to help identify someone?
- Can the physical characteristics of an object in a photograph be determined?
- Can individuals an offender targeted or victimized be determined?
- Can unknown victims be located or identified based on phone number, email, etc.?
- Can patterns of offender activity related to the investigation be reconstructed?
Education and Training
Photographic analysis using photogrammetry
Candidates for an apprenticeship program in digital and multimedia sciences should possess a minimum of a bachelor’s degree, preferably in computer science, information technology, or engineering. In the United States, there are undergraduate degree programs with emphasis in digital forensics, computer forensics, and media forensics. There are also graduate degree and graduate certificate programs in these fields. Digital forensic examiners also may have various types of certifications. A certified professional not only possesses technical competency but also adheres to a strong code of ethics.
Digital forensic examiners are employed in both the public and private sector. Private practice consultants can be found in most major cities. Many large police organizations as well as most state and federal law enforcement agencies, generally employ digital forensic experts. Scientists who specialize in the field of digital & multimedia sciences work or practice in the following forensic areas: computer-related crime investigator; computer specialist; image analyst/examiner; audio analyst/examiner; video analyst/examiner; speech scientist; and, facial identification/biometrics.
Many qualified practitioners are members of the American Academy of Forensic Sciences (www.aafs.org), International Association of Computer Investigative Specialists (www.iacis.com), the High Technology Crime Investigation Association (www.htcia.org), the International Society of Forensic Computer Examiners (www.isfce.com), the Audio Engineering Society (www.aes.org), the International Association of Identification (www.theiai.org), the Law Enforcement & Emergency Services Video Association (www.leva.org), the Institute of Electrical and Electronics Engineers (www.ieee.org), and other professional groups and societies.
Audio analysis of a sound sample.