Technically, the captured members of the resistance were not considered as POWs by the Geneva Conventions. This is because the French resistance, for example, did not wear uniforms or identifying marks visible at a distance, nor did they carry arms openly. This is a difficult issue, since they also do not fall into any of the other protected classes under the conventions-- civilians, sick, wounded, shipwrecked, etc. Article 4 of the Geneva Convention Relative To The Treatment of Prisoners of War (12 August 1949) was not in effect during WW2, but this post-war modification seems to specifically exempt most resistance forces from being considered as POWs. Article 4, PARA A discusses who POWs are, and subpart (2) says that resistance forces are included as POWs ONLY if they meet certain conditions: " a) being commanded by a person responsible for his subordinates; b) that of having a fixed distinctive sign recognizable at a distance; c) that of carrying arms openly; and d) that of conducting their operations in accordance with the laws and customs of war." Since the French Resistance of WW2 (for example) did not comply with subparts b) and c), I would read this as saying that the Germans could have legitimately treated them as common criminals under the law of the German occupation. I don't currently have at hand the version of the conventions which was in effect during WW2, but from memory of when I took a course on the conventions at the ICRC, I believe it left the status of resistance fighters to be defined by the occupiers, and did not include them in POW status. Thus, they basically were left out of the Geneva Conventions, and this status was not changed in the 1949 revisions. German treatment of them as common armed criminals was not prohibited by the conventions.