When it comes to citizens of other countries just temporary residing in Ruritania, it may be more appropriate (cheaper, "not our problem") to just send them back, guilty or not, to be decided by a justice system in their own country. Preferably, after evaluating if there is a reasonable expectation of a fair trial.
Releasing them to some third party (in this case, a German citizen to US authorities) sounds absolutely awful to me. Barbaric from the perspective of the person being sent away, and servile from the perspective of sovereign people.