What is the place of human testimony in the investigation?

Human testimony is at the core of the process and methodology for GEIPAN.
GEIPAN only investigates phenomena reported by one or more direct witnesses of the observation.
The witness must fulfil the technical questionnaire (QT), designed to gather the essential and substantial information to open an investigation.
Visual, material or detection matters such as sketches, photographs, videos, etc. may complete the QT.