The deprivation of physical liberty in the context of NIACs has stimulated research and publication in the field of IHL for several years. Within the Colombian transitional justice process, where conduct related to a NIAC spanning for more than half a century are currently being prosecuted, the legality of several instances of deprivation of physical liberty by FARC-EP, a non-state armed group, against State armed forces, is a relevant object of study. An important point of departure for the authors is their understanding of the catalyst role played by the Special Jurisdiction for Peace, given the active participation of those allegedly responsible, the victims and the communities in the legal qualification of the conducts under examination. With this case in mind, the authors analyse the IHL regulation over deprivation of physical liberty in relation to three different moments: (i) retention; (ii) captivity; (iii) and release. Considering the developments and gaps remaining in the international regulation, the purpose of this work is to advance an interpretation proposal of this phenomenon based on the complementary interaction of the relevant norms in the Colombian transitional justice model and the complex realities of armed conflicts.