Anyone convicted or accused of a crime is subject to - and protected by - the relevant provisions of the law. No-one can fall outside the reach of the law.
In the case of internal strife the status of the prisoners is determined by the relevant national authority. In the case of international armed conflicts their status is governed by the Geneva Conventions - which state that, should there be any doubt as to whether a detainee is a prisoner of war, a "competent tribunal" should decide.
More on this: Visiting people deprived of their freedom: legal safeguards - factsheet (August 2001)