· Observable physical evidence such as tracks and footprints, clothes, bullet or shell casings; observations made at the site of a human rights violation or a crime scene, such as distances between objects, layout of an area, visibility from various vantage points, terrain. Taking photos or video of the scene, where possible and secure, is generally encouraged. · Imagery, photos and videos – imagery such as that from satellites101 or drones, which might locate a certain type of tank or artillery piece at a given moment, or civilian objects (satellites can also provide before and after images of areas exposed to attack, for example to show destruction or the location of disturbed earth or gravesites); photos and videos – where they can be authenticated (i.e., the source can be verified to the relevant evidentiary standard) and photos taken by the investigators. Official open sources102 · National laws and policies and national court records – of the government concerned, as well as internal documents, provided they were received from a reliable source and their authenticity could be confirmed; · Military and security forces’ websites and materials; · Social networks (Twitter, Facebook, YouTube, Snapchat, etc.) and other means of communication deemed to be the “official�� sources for non-State actors, or that suspects might use. Other open sources · Research and reporting by civil society, human rights defenders (HRDs), think tanks, institutions and analytical organizations. · Media reporting (including print, radio, television and online). OHCHR has a memorandum of understanding in place with UNITAR/UNOSAT (United Nations Operational Satellite Applications Programme) to provide imagery and analysis. 102 See below, section (c), “Publicly available information, open sources and social networks”. 101 COLLECTING AND ANALYSING THE INFORMATION 55