How to ensure the authenticity of synchronized audio and video evidence

Abstract: The purpose of synchronous audio and video recording in interrogation places is to fix audio-visual evidence, so synchronous audio and video recording should be carried out around audio-visual evidence. Synchronous audio and video recording is audio-visual materials used in criminal proceedings, based on audio tapes, video tapes and CDs. Synchronous audio and video recording by procuratorial organs: [Keywords]: [Text]: The purpose of synchronous audio and video recording in interrogation places is to fix audio-visual evidence, so synchronous audio and video recording should be carried out around audio-visual evidence. Synchronous audio and video recording is audio-visual materials used in criminal proceedings, based on audio tapes, video tapes and CDs. The synchronous audio and video recording work of procuratorial organs not only extracts evidence but also fixes it. Then, will this audio-visual material be accepted in court and can it stand the test of the material evidence institution? The author thinks that the following three points should be paid attention to in the formation of evidence chain of synchronous audio and video recording: 1. The recording equipment shall be easy to identify and its contents shall not be changed. How to identify products? Look at the first storage medium of the device first. With the wide application of computer technology, the working equipment that uses simple PC+ software mode and hard disk video recorder mode for synchronous recording and recording has appeared one after another. They mainly use hard disk as the first storage medium of original evidence. Because of its many auxiliary functions, it is favored by some grass-roots procuratorates. However, because its first storage medium is hard disk, which has the characteristics of strong erasability and repeated writing, the video content generated by it is easy to be modified, and criminal suspects, judges and lawyers are highly concerned about this. If we cache it in the memory of hard disk or PC first, and then burn the CD, it is easy to raise an objection. Therefore, whether to store synchronized audio and video in hard disk or memory before recording depends on whether the content stored in hard disk can be identified by physical evidence. At the same time, according to the requirements of physical evidence, this hard disk with original evidence should also be sealed independently. Accordingly, the author suggests that it is best to use synchronous direct recording equipment with digital encryption function of CD track and synchronous storage of independent video recording on hard disk as audio and video recording equipment. Because the CD itself has physical characteristics that cannot be edited manually, it can be used as the first original evidence, and the hard disk is only used for synchronous and independent backup, which not only ensures the authenticity and identification of the original CD as the first storage medium of evidence, but also prevents the CD from being switched, and at the same time avoids the suspicion of modification and the loss of audio-visual evidence state during the asynchronous transfer of the hard disk to the CD. While audio-visual materials and fixed evidence are directly engraved synchronously, the direct fixed equipment should adopt embedded data random encryption system to digitally encrypt the video track of the original evidence CD point by point to prevent the original CD from being artificially replaced. This encryption system cannot be set artificially. The material evidence appraisal institution can use the optical disc inspection equipment to appraise and authenticate the encrypted authentication information code in its optical disc track. The original CD can also be played or copied in any media player. The copied CD does not have the encrypted authentication information code of the original CD. The criminal suspect signs the audio and video information recorded on the original CD according to this English-digital mixed code, which can not only ensure fairness and justice, but also facilitate the identification of the CD by the physical evidence appraisal institution in case of dispute. The author thinks that synchronous audio and video recording equipment should form the following evidence fixed chain: time code+environmental information synchronization+CD direct engraving+CD track digital encryption+CD electronic video number+dual-disk synchronous real-time fixation+hard disk independent backup. It should be noted that at present, some devices, on the surface, can burn CDs, but in fact they use asynchronous delay hard disk transmission mode, and the evidence of this fixed mode will also be questioned. Physical evidence appraisal institutions also do not accept this controversial evidence. Therefore, when selecting equipment, we should also consider whether the equipment has been demonstrated by the authoritative material evidence appraisal institution of the state or passed the scientific and technological appraisal at or above the ministerial level, and at the same time, it has the production license of audio-visual forensics products issued by the relevant functional institutions of the state, so as to avoid using temporary equipment and prevent the waste of funds. 2. Strict relevant technical specifications and workflow. The problem of audio-visual materials being forged and tampered with has attracted more and more attention in the field of material evidence identification and trial. The physical evidence appraisal department has formulated strict inspection procedures for controversial audio-visual evidence. In addition to the voiceprint synchronization and frame field identification of the audio-visual evidence storage medium and its contents, special attention is paid to the strict examination of the audio-visual equipment that fixes its audio-visual materials, such as the verification of the evidence fixing equipment to identify whether the audio-visual evidence is suspected of tampering in the final media storage process. Therefore, the author suggests to avoid using PC-type devices with programming function or devices that rely on transfer between storage media to fix evidence. 3. Identification and inspection. The appraisal of the material evidence appraisal department should first test the scientificity, rationality, rigor, synchronism and invariance of synchronous audio-visual materials and storage media; Secondly, the reliability of the original CD of fixed audio-visual materials is tested. In the process of collecting and fixing audio-visual materials, audio-visual materials also need to be tested; During the trial, as long as the interrogation process recorded in the form of video is played in court during the trial, the defendant's excuse for recanting will be broken. If the collection method is improper or the audio-visual materials provided have no inspection conditions, the suspect will question the originality of the audio-visual materials. In short, audio-visual materials can be easily copied and forged, and only audio-visual materials that have been tested by legal procedures can be used as evidence. With the all-round development of synchronous audio and video recording, we should carefully understand the connotation of synchronous audio and video recording and avoid repeated construction when choosing equipment and methods, especially from the perspective of physical evidence. Procuratorial organs should attach importance to the evidence in synchronous audio-visual recording, and take whether the court accepts the letter as the foothold of synchronous audio-visual recording. (Jiangxi Provincial Procuratorate Zhang Lidong)