Although second-hand, and with the caution previously expressed with regard to authenticating videos and photos, this information is useful in investigating the action of this armed group. Facebook pages of armed groups also provide some information on the hierarchy of the group, the area in which they operate and some of the incidents in which they have been involved. (h) Reports of United Nations mechanisms, intergovernmental and non-governmental organizations In situations where large-scale human rights violations are occurring, there are likely to be many international and non-governmental organizations collecting information similar to that which the commission/mission sets out to collect. United Nations reports, including those of special rapporteurs, may have information that could assist the commission/mission in setting its priorities and provide valuable leads for investigations. Often, regional intergovernmental organizations such as the European Union, the Organization for Security and Co-operation in Europe and the African Union will have observers in the country or region and their reporting, if made available, can be of value to the investigation. International human rights NGOs write detailed reports, interview victims and witnesses, and have extensive contacts among groups of victims and witnesses, and the authorities. While the commission/mission could easily access the public reports of these NGOs, other information such as the contact details of victims, witnesses and local authorities in the country concerned may not be in such reports and may need to be accessed through direct contacts. Local and regional NGOs, including, for example, those providing services such as medical care and education, have established contacts with communities and their leaders, and often have valuable information. 3. INFORMATION-GATHERING METHODS (a) Interviewing Interviewing is one of the most common methods used by commissions/missions to gather information. Some interviews seek to obtain first-hand information on violations, while others may seek to verify information already gathered by the commission/mission. In some instances, investigators can plan and prepare interviews in advance based on pre-identified lists and have some prior knowledge of the interviewees and the information they are likely to provide. In many situations, however, investigators access victims and witnesses with little advance notice or meet them when visiting a refugee camp or a site of human rights violations. In any event, the commission/ GUIDANCE AND PRACTICE 49