Ambassador Christian Guillermet-Fernández was the Chair of GAAMAC from November 2023 to August 2025. He has been a career diplomat in the Costa Rican foreign service since 1998 and, from April 2020 to June 2023, was appointed as Deputy Minister of Multilateral Affairs. During his experience in the Foreign Service and in the Ministry of Foreign Affairs and Worship, he worked as Ambassador and Deputy Permanent Representative at the Permanent Mission of Costa Rica to the United Nations in New York (2019-2020); Director General of Foreign Policy of the Ministry of Foreign Affairs of Costa Rica (2016-2018); Deputy Director General of Foreign Policy (2015-2016); Deputy Permanent Representative of Costa Rica to the United Nations in Geneva (2010-2015); Deputy Permanent Representative and Political Coordinator during Costa Rica’s membership in the Security Council at the Permanent Mission of Costa Rica to the United Nations in New York (2008-2009); Director General of Foreign Policy after working with the Office of the United Nations High Commissioner for Human Rights in Geneva and in Santiago, Chile as Regional Representative a.i. of the High Commissioner (2006-2008). From 1993 to 1998, Ambassador Guillermet-Fernández was an official in the Office of the Ombudsman of Costa Rica, at the beginning of the creation of the Institution. During his diplomatic career, he worked as Chair-Rapporteur of the United Nations Open-ended Working Group on the Right to Peace, among others. In addition, he has collaborated extensively with different universities and think tanks and has written for prestigious peer-reviewed journals worldwide.

Silvia Fernández de Gurmendi was the Chair of GAAMAC from 2020 to 2023. She is a former Judge and President of the International Criminal Court (ICC). She is currently the President of the Assembly of State Parties of the ICC and President of the Latin American Society of International Law. She has extensive diplomatic experience and expertise in international humanitarian and human rights law. Among other functions, she has been Special Representative of Argentina to the International Holocaust Remembrance Alliance (IHRA), Director General for Human Rights at the Ministry of Foreign Affairs of Argentina and legal adviser at the Permanent Mission of Argentina to the United Nations in New York. She has played a leadership role in the creation and setting up of the ICC. She holds a Law Degree from the University of Cordoba (Argentina), a Master Degree in Public Law from the University of Limoges (France) and a Ph.D. in Law from the University of Buenos Aires (Argentina). She speaks Spanish, English and French.

Mô Bleeker acted as the first GAAMAC Chair until November 2019. Former Special Envoy on Dealing with the Past and Prevention of Atrocity at the Swiss Federal Department of Foreign Affairs (FDFA), she has been working for decades in societies engaged in processes of transition, and/or in peace processes in Central America, Colombia, the Balkans, South Caucasus, South and South East Asia, Central Asia, Central, North, and West Africa. She chaired the Transitional Justice and Reconciliation Commission in the Philippines created in 2014 and acted as Chair of the International Advisory Board of the National Historical Memory Commission in Colombia. From 2017 until end of 2021, she also acted as Special Envoy for Peace in Colombia. She holds degrees from  the University of Fribourg (Switzerland) and  the Graduate Institute of International and Development Studies in Geneva.