Initial selections were made from several demographic POW groups, Catholics, Austrians, and those who had been assigned to punitive battalions because of their political views. Potential recruits were cleverly transitioned from the main prison population through assignment to work details. After days of observation, the candidates were given intense interviews to determine their motivation to “betray their country” by returning to Germany as American spies.
The OSS disagreed. They used Germans to spy on Nazi Germany.
https://nationalinterest.org/blog/buzz/hitlers-nightmare-meet-americas-spies-nazi-germany-148301