One of the last aircraft shot down in the European theater of WWII was a Piper Cub that shot down a Fieseler Storch with a .45 pistol. They landed next to the crashed Storch, captured the pilot, and treated his injuries. Then handed him over to the Russians, who I am sure also treated him in accordance with the provisions of the Geneva convention.
The current Geneva Convention was in 1949, but the original Geneva Convention dates back to 1864.
Of course, the previous poster is noting that the USSR blithely disregarded the conventions for others' POWs as well as its own: most returning soldiers were considered traitors to the Motherland and summarily executed or sent to the Gulag to die more slowly.
https://theaviationgeekclub.com/that-time-a-usaaf-piper-l-4h...