Other maps are also helpful, such as those detailing camps or places where violations occurred. A detailed chronology of events that is linked to locations and to individual units and command structures should be a priority for all investigations. (c) “Linkage evidence” So-called linkage evidence is information “linking” mid- and higher-level commanders to the violations or crimes of their subordinates, in what may be referred to as “multilevel investigation” because it involves making a connection between the perpetrators at ground level and those higher up the chain of command. It is relevant not only for showing responsibility for international crimes, but also for demonstrating that certain leaders acted as agents of human rights violations. For example, linkage evidence can help prove that a particular decision maker ordered, or was otherwise complicit in, unlawful surveillance, censorship or a discriminatory practice. Understanding how to demonstrate these links is especially helpful when an investigative body is confronted with complex political and military structures. Aside from direct eyewitness and defector accounts, documentary linkage information such as official records, military annual reports, official press releases, public statements, websites and other publications or archives can be highly probative. Written materials that tend to show the existence of hierarchies, and who within those hierarchies wields de jure command, are also relevant – though again, de facto rather than de jure control must ultimately be shown. Logistics and supply reports, for example, can show when specific units were at specific places and that the commander signing the papers probably knew they were there. The documentation of patterns can show that specific sets of violations must have been ordered by individuals at the top of the hierarchy. Particular challenges are posed in seeking “linkage evidence” when investigating armed groups, as – especially early in an armed conflict – their administrative procedures may often be less developed or thorough. Other sources such as social media, defectors or detainees may prove more valuable. Thinking through the various ways to secure linkage evidence should be a core part of investigation planning. 48 ATTRIBUTING INDIVIDUAL RESPONSIBILITY