In this article, we analyze three forensic and counter-forensic devices that go beyond the strictly medico-legal realm to show which concrete practices and truth-spots contribute to (re)constructing a public account of migrant deaths and disappearances along border zones. Drawing on written documents and semi-structured interviews, we examine operations led by the International Committee of the Red Cross (ICRC) in Europe and Africa, the work of the Pima County Office of the Medical Examiner (PCOME) together with the NGO Colibrí Center for Human Rights in Arizona, and Forensic Oceanography's (FO) open-source investigations of shipwrecks of migrants in the Central Mediterranean Sea and the structural violence embedded in militarized border regimes. We argue that these practices constitute factualization devices, namely practices that transform lived experience of death and disappearance into an objectified reality that can be visibilized and mobilized in the public sphere as part of a counter-narrative. We demonstrate how these factualization practices are imbricated in valuation practices, i.e. practices that ascribe not only an epistemological but also an ethical, aesthetic and political value to the work of objectification, which inform the production of truth narratives.