A/HRC/42/CRP.1 direct information about incidents under investigation. The Group of Experts further supplemented the in-person interviews with interviews using remote methods. 34. The Group of Experts reviewed satellite imagery and obtained expert analysis from UNITAR-UNOSAT5 which supplemented its own internal review of the imagery. The Group reviewed documents, photographs and videos, including recordings made by witnesses to events and judicial documents, including prosecution files, which included detailed testimonies and interrogations of detainees. Findings were made using only those materials that the Group was able to authenticate. The Group of Experts also collected, reviewed and analysed information drawn from a variety of open sources. Examples of such sources include social media, news and media outlets, geospatial imagery and forums. The analysis of information drawn from these sources served two purposes. First, information drawn from open sources was at times used as an initial source of information relating to specific incidents or events, and provided a basis for further investigations, during which the Group considered whether it had sufficient corroborating evidence. Second, information drawn from open sources was at times used to corroborate and verify information provided to the Group through traditional human rights investigative practices, such as interviews with witnesses, victims and experts. In all cases of review of open source material, the authenticity, veracity and credibility of the content was established through best practices of current open source analytical methods. 35. Despite the physical access constraints faced by the Group of Experts due to lack of cooperation and the chilling effect that threats by some of the parties had on witnesses, victims, and organisations who cooperated with it, the Group was nevertheless able to gather evidence to support the findings in this report. The Group of Experts notes that the findings in this report, while limited due to resources, time, and access, aim to give an indicative sample of the human rights violations, especially the most serious ones, occurring in Yemen. The Group of Experts further reiterates that its investigations so far have only touched upon a very small number of the allegations, and recommends continued investigations into the incidents and patterns of conduct discussed in this report and in its two reports to the Human Rights Council (A/HRC/39/43 and A/HRC/42/17). 2. Calls for submissions 36. In addition to gathering evidence by conducting interviews with known victims, witnesses, and other direct sources about whom it was already aware, the Group of Experts extended invitations through notes verbales to United Nations Member States and United Nations agencies, departments and bodies and to regional organizations to provide information relating to the investigations. The Group of Experts also circulated public calls for written submissions from non-governmental and other organizations and individuals interested in bringing information to the attention of the Group of Experts in February 2018 and February 2019. The Group of Experts is grateful to all of the organizations and individuals that provided information in response to its calls for submissions. 3. Letters to parties to the conflict including lists of issues and requests to access Yemen 37. In April 2018, the Group of Experts sent detailed letters to the parties to the conflict, requesting access to Yemen, meetings with officials, and written clarification and information on a number of issues relating to its investigations. 6 The Group of Experts requested responses from the parties by May/June 2018 in order to be able to include information received in the report to the thirty-ninth Council session. The Group of Experts further sent detailed queries on specific cases/incidents in June 2018. 5 UNOSAT is the Operational Satellite Applications Programme of the United Nations Institute for Training and Research (UNITAR). All UNITAR-UNOSAT damage assessments in this report are available on the website of the Group of Experts at: http://www.ohchr.org/en/HRBodies/HRC/YemenGEE/. 6 These ‘list of issues’ letters sent to the parties in 2018 and 2018, as well as the responses from the parties, are available on the website of the Group of Experts at: http://www.ohchr.org/en/HRBodies/HRC/YemenGEE/. 10