There is an excellent book called The Forgotten 500 which talks about his role in assisting in the rescue of 100’s of airmen that had to bail out over Yugoslavia. Those airmen tried to intervene on his behalf.
The US government, in particular the State Department, did not intervene because the Brits had a double agent feeding misinformation to them about him.
The US awarded a medal to him posthumously which was kept secret in the State Department until recently, when it was given to his daughter by some of the surviving airmen.