Document Examination and Audiovisual Techniques Department

Audiovisual Technique Unit

Experts from this Unit carry out research and development activities as well as forensic examinations of high complexity, requiring the application of unique analytical instrumentation.

The area of responsibility of Audiovisual Technique Unit includes voiceprint examination, such as identification of persons, determination of authenticity of recordings, audio examinations and copying of audio recordings with use of correction technique and – if required – change of audio carrier.
Identification of persons based upon speech includes examination of evidence material in form of various kinds of audio recordings, which contain speech of examined persons. In majority of cases, these recordings represent the course of a specific event, conversations (one-to-one or via phone), voice messages, etc. Exhibits include audio and video tapes (sound only), CDs, memory sticks, minidiscs, digital dictaphones, mobile phones, etc. Other important area of examination concerns the determination of authenticity of analogue tape recordings. This task, involving a multi-stage analysis and unique microscopic examination of tape magnetisation image, is performed exclusively by CFLP experts on the nationwide scale.

The scope of expert activity in terms of visual examination includes making forensic photographic and video documentation, recording of the course of scene of crime investigation and experiments, taking photographs for research or demonstration purposes, enhancement of writing, print, illegible, obliterated or chemically and mechanically treated writing with use of special photographic techniques, photo processing, conversion of video recording into photographic documentation used for identification of persons and objects, identification of image recording devices.

In their work, experts employ, among others, a specialist computer workstation for CCD cameras image quality enhancement and digital camera for spatial, 3D photographic recording of crime scene.

In IT and Digital Examination Unit, experts deal with cases involving computer examination and requiring the analysis of information contained on various digital data carriers, the most common being mobile phones (SIM cards). The analysis of information in digital form (hard disk, FLASH memory, diskette, CD, DVD, etc.) is carried out in order to recover data (quite often intentionally or unintentionally deleted by a user), as requested by law enforcement or judicial bodies.