Recognized for his field-based expertise, he has directed complex human rights and war crimes investigations, advised national and international accountability mechanisms, and championed survivor-centered approaches that have become global benchmarks in the pursuit of justice.

He has served in senior leadership roles across multiple United Nations mandates, including Head of Mission and Chief of Operations for the International Criminal Tribunal for the former Yugoslavia (ICTY), where he coordinated with national authorities the exhumation of mass graves and managed sensitive war crimes investigations in Croatia, Bosnia and Herzegovina, Albania, and Kosovo.

As Field Investigation Coordinator for the UN Commission of Experts, his work alongside Cherif Bassiouni and UN Special Rapporteur Tadeusz Mazowiecki was instrumental in securing international recognition that rape and sexual violence in conflict constituted war crimes under international humanitarian law.

Mr. Osorio has been a driving force in advancing regional justice and reconciliation in the Western Balkans, co-founding the Palić/Brijuni Process, the adoption of national transitional justice strategy in BiH, chairing the regional reconciliation dialogue of the Civil Society Forum within the Berlin Process, and established victim and witness support systems in Croatia and Bosnia and Herzegovina.

In academic and advisory roles, including Visiting Professor and Senior Research Associate at KU Leuven University, he has advanced research on male-directed sexual violence in conflict and delivered specialized training on trauma-informed interviewing and militarized masculinities for Swisspeace, the European Commission, UNDP, and others.

Notably, Mr. Osorio was the first UN Human Rights Field Officer deployed to an active conflict zone, pioneering investigative protocols, survivor-centered engagement strategies, and inter-agency coordination frameworks now standard across UN peacekeeping missions. His career reflects an unwavering commitment to ensuring that survivors’ voices are heard and that the path to justice remains open.