Digital editing is making the job of detecting altered recordings much more difficult. Because of this, it is very important that the identical CODEC and/or the original storage device be available when attempting to detect alterations in the recorded event. Procedures have been developed by the FBI to provide a comprehensive overview as to what is considered essential to make a valid scientific analysis for detecting alterations.
There must be allegations or sworn testimony from plaintiffs, the defense or other witnesses as to tampering having occurred. The description of this tampering must be as complete as is possible, including:
- Location of recording
- Type of alteration believed to have taken place
- Chain of Custody
- Completed scientific testing
If the original recording was captured on a HDD or SSD, and the manufacturer’s duplication process was followed, a digital copy in the same format/codec as the original recording may be examined for authentication. But if the original recording was made on tape, the original must be submitted; authentication of duplicates cannot be completed and copies may not be provided for examination. Whether recorded on HDD/SSD or tape, the original recording equipment should be made available for examination. If maintenance has been carried out on the relevant recording components, written verification of these changes must also be provided. A statement from the individual(s) who completed the recording must also be included; it must have production notes and conditions during recording stated as clearly as possible. Some of these conditions may include:
- Recorder power source (AC power, generator, batteries, UPS, etc.)
- Recording input (a/v video line, USB, HDMI, DVI, LAN-telephone link, transmitter, etc.)
- Recording environment (public, retail, residential, interior-exterior, power backup, etc.)
- Background noise identification (radio frequency, 60 Hz ungrounded loop, HF interference, appliances, etc.)
- Foreground noise identification (individuals conversing, ambient environment, microphone position, etc.)
- Tape format, brand, manuf. batch number (purchase date, new or used, etc.)
Recording authentication is a difficult and tedious task. Not only must a determination be made regarding authenticity, but microscopic details must be taken into consideration, as well. Much information is required and must be available for authentication to occur.