United Nations Commissions of Inquiry (CoIs), Fact-Finding Missions (FFMs) and similar complex human rights investigations are regularly, and with increasing frequency, called upon to ‘identify those responsible’ for violations and crimes falling within their mandate. Yet identifying responsible parties poses complex legal and methodological challenges. Despite variations in mandate language, applicable legal regimes, political context, membership, timing and budgets, the practice of CoIs, FFMs and similar complex investigations is developing in this area. OHCHR has a wealth of institutional experience in human rights field investigations where the identification of allegedly responsible individuals is a regular feature. This guidance draws upon that practice and presents it together with a discussion on key policy issues, namely the collection and analysis of information on responsible individuals, and the legal and investigative challenges involved; and the management of information once collected, including maximizing its use (by reporting, sharing and safeguarding it). The publication builds on OHCHR’s existing guidance and practice for CoIs, FFMs and other investigations and sets out both the minimum steps that all investigative bodies should complete as well as additional measures that can and should be taken where feasible. This information is complemented by Recommendations or a Summary of key guidance on the points raised